Optic Aphasia: A Case with Spared Action Naming and Associated Disorders

BRAIN AND LANGUAGE 53, 183–221 (1996)ARTICLE NO. 0044

Optic Aphasia: A Case with Spared Action Namingand Associated Disorders

RUTH CAMPBELL AND LILIANNE MANNING

Goldsmiths College University of London and National Hospitals, Queen Square,London, United Kingdom

AG, a pure case of optic anomia (object naming impaired; action naming good) isdescribed. We consider the fit of experimental data from AG to different theoreticalaccounts of optic aphasia. Overall, we find no evidence for impairments intrinsicto semantic representations, but we note a number of problems that we interpret asindicating a slight, and specific, weakness in semantic access from vision. We alsonote a mild problem in generating names to a cue (verbal fluency). The main aimof the report was to provide a full description of tests of visual, semantic, and speechoutput skills in this patient in relation to the processing of visually presented objectsand scenes, within a sequential information processing account which enablessome theoretical implications to be drawn, albeit not conclusively. 1996 Academic

Press, Inc.

INTRODUCTION

The modality-specific aphasias (e.g., optic, tactile, auditory) are amongthe more inscrutable clinical aphasias. This report concerns optic aphasia, theclinical condition of impaired naming from visual confrontation. All patientsdescribed to date have left-hemisphere occipital lesions, typically mediallyplaced. Table 1 details the reported cases with the relevant test results.

In an earlier paper (Manning & Campbell, 1992) we presented a versionof this case, reporting a range of experimental tests. In this paper we set thisreport in a more detailed experimental and theoretical context and provide

We are grateful to AG and his family for their patience and kindness. This work was startedat the Neuropsychology Unit, Radcliffe Infirmary, Oxford and supported in the part by a MEC/Fleming Fellowship (Manning). We thank Dr. John Hodges who referred the patient and MariaBlack, Sally Byng, Roberto Cubelli, Elaine Funnell and John Marshall for enlightening discus-sion at various stages. We are grateful to Elizabeth Warrington, Jane Riddoch, David Howard,Freda Newcombe and Charles Heywood for the loan of various tests. The writing of this paperwas supported by MRC (UK) Grant G8811259N to R. Campbell and L. Manning. Addressreprint requests to Ruth Campbell, at the Psychology Department, Goldsmiths College, LondonSE14 6NW, U.K. E-mail:[email protected].

1830093-934X/96 $18.00

Copyright 1996 by Academic Press, Inc.All rights of reproduction in any form reserved.

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OPTIC APHASIA 185

fuller evidence, qualitative and quantitative, of AG’s performance. Tests re-ported in both papers are marked (*), with more details in the present paperthan in that Note.

Optic aphasic patients can name objects and events from all save the af-fected modality, yet show no apparent sensorially based impairment. More-over, patients typically show intact comprehension of the items that theycannot name. This is difficult to understand as a unitary deficit on most com-monsense views of the number, type, and sequence of necessary processesin naming to confrontation. For visually presented objects (and hence in con-sidering optic aphasia) it is generally agreed that visual object recognitionis the first stage in information processing. Perceived objects access semanticmemory so that recognition, categorization, and other aspects of visualknowledge are achieved. Then from semantic memory the name of the per-ceived object is accessed and produced. Such simple, serial, three-stage mod-els (see for example, Ellis & Young, 1988) cannot accommodate optic apha-sia without modification. Any presemantic impairment, as proposed, forexample, by Riddoch and Humphreys (1987), should affect all cognitivetasks that depend on the visual modality. Riddoch and Humphreys suggestthat, on the whole, the demonstration of an adequate gestural response toseen stimuli does not invalidate the impaired semantic access proposal: ges-tures are rarely as specific as names in their mappings to semantic representa-tions. Similarly, associated deficits—of visual processing and of semanticclassification from vision—are implied by this scheme. A postsemantic im-pairment, that is any problem in activating an output word-form system (inretrieving the appropriate word-form) as suggested by Bisiach (1966),should, again, be independent of the modality of the stimulus. This proposedlocus—that of a vision-specific pure anomia—also implies associated prob-lems and characteristics. In this case we might expect verbal fluency to bepoor and cuing, by giving the initial sound or other feature, to help retrievethe sought-for name.

If the impairment is intrinsic to semantic processing, then representationsat this level ought to be distinguishable as a function of their mode of inputand output; that is, on this account of a deficit in central representationalprocesses such representations must be modality-tied and multiple, not uni-tary (Beauvois, 1982; Shallice, 1987, 1988). For example, Beauvois and Sail-lant (1985) suggest that optic aphasia reflects a disconnection between linkedsemantic systems, one geared to vision, one to naming. Again, associateddeficits are implied: in this case, the strictly visual characteristics of objectsmay not be described in words and the nonvisual aspects of objects (e.g.,some functions and also associated verbally based knowledge) may not beaccessed from pictures. Patient MP, whom they report, was unable to namethe characteristic colors of objects, except when these names were basedon verbal associations (‘‘white as snow’’). Another proposal, which can beconstrued in a somewhat similar way, yet which retains elements of theories


of access/output disorder, is that in optic aphasia there is a disconnectionwithin a distributed semantic system between vision-linked and name-linkedprocesses. This in turn maps onto cerebrally localized processes. Thus, Cos-lett and Saffran (1989) suggest that optic aphasia may be regarded as a formof functional hemispheric disconnection: the right hemisphere can processseen material but cannot make its decision available to left-hemispherespeech centers. The deficit is vision-specific since only the visual centers ofthe cortex are disconnected from other (semantic and linguistic) processes.This is because of the central, occipital site of the lesion which effectivelyisolates input from transmission through the splenium. Associated disorderson this sort of account might be those for which a disconnection story isalready plausible; for example, pure alexia (Geschwind, 1965). A location-neutral version of differential semantic access from vision and from lan-guage, which blurs the access-representation distinction while maintaininga strong position in favor of unitary semantic structures, has been indicatedby Caramazza, Hillis, Rapp, and Romani (1990). They point out that seman-tic representations are multifarious rather than multiple. Any event, object,or concept can be characterized in terms of a very wide range of meaningdistinctions: conceptual, sensory, abstract, distributional, linguistic. Somemodes of input have more intimate connections (privileged access) to someof these features than others. Optic aphasia would result when there are prob-lems in accessing those aspects of meaning that are most appropriately deliv-ered by vision. Thus, while a picture of a chair may afford recognition of asemantic representation in terms of concrete, perceptually salient aspects(such as seat and four-legs), rather different aspects of the meaning of,chair. will be accessed when the word is spoken (general function, forexample—but also possibly, part of—speech).

A different approach, based on close analysis of a series of case histories,is taken by Farah (1990). She also outlines a serial three-stage model, wherevisual analysis precedes (unitary) semantic activation which in turn precedesnaming, but she points out that optic aphasia need not result from a singleunitary deficit. In an interactive system where several stages of processingoccur in cascade, small impairments at more than one site of processingcould have superadditive effects when combined. For optic aphasia, individ-ually negligible presemantic and postsemantic impairments could suffice tocause a clinical impairment in naming which is confined to seen material.This approach suggests that deficits associated with the proposed access im-pairments may be very slight indeed, since it is only in combination (namingto visual confrontation) that the impairment is manifest. Farah’s proposalmay run into difficulties in terms of an empirical program of testing inpatients/subjects, since it suggests that the associated access impairmentsmust be negligible and the empirical demonstration of a set of negligibleimpairments is paradoxical. For this reason, if for no other, computer simula-tion of the proposed interactive stages may provide more useful evidence of

OPTIC APHASIA 187

the validity of the proposal. To date, no such successful simulation has beenreported.

One computer simulation of some aspects of optic aphasia has recentlybeen reported by Plaut and Shallice (1993a). Their model instantiates a se-mantic system in a unitary way: there are no subdivisions between ‘‘visual’’and ‘‘verbal’’ semantics. The semantic domain is characterized by a largerange of features (e.g., size, shape, action-affordance, animacy, pleasantness,etc.), which can take different values. The Plaut and Shallice account of theerror pattern of optic aphasia is based on principles first outlined by Hintonand Shallice (1991), featuring semantic attractors. This model was first de-veloped in the context of deep dyslexia, where it predicted the characteristiccombination of visual, visuo-semantic, and semantic errors made by deepdyslexic patients in terms of changes in the (learned) connection weightsbetween visual (orthographic) and semantic units. The role of semantic at-tractors (which used specific clean-up units at the semantic level of represen-tation) became crucial in predicting the detailed pattern of performance inthat syndrome, for example, in predicting concrete-for-abstract word errorsand the general accessibility of concrete over abstract words (Plaut and Shal-lice, 1993b). Moreover, since the learning algorithm led to visually similarinputs being sometimes represented in neighboring parts of semantic space,when connections were lesioned, the semantic attractor basins could some-times attract visual neighbors. That is, increased shallowness of semanticattractor basins (the computational consequence of lesions to vision-to-semantics pathways) tended to generate visual errors as well as visuo-semantic or semantic errors.

For optic aphasia, Plaut and Shallice (1993a) showed that a similar patternof visual, visuo-semantic, and semantic errors may follow lesions to the vi-sion-to-semantics connections in a network that has learned the semanticfeatures of visually presented objects. That network did not include a phono-logical output layer, and so the anomic character of optic aphasia was notcompletely simulated. (The simulation did include a mechanism for generat-ing perseveration errors, typical of optic aphasia, based on the establishmentof short-term connection weights to simulate the effects of earlier presenta-tions on current ones). The Plaut and Shallice model suggests that the vision-to-semantic impairment is necessary and sufficient for optic aphasia. It isthus a simulation of a ‘‘semantic access’’ approach to optic aphasia. In thismodel, as in the earlier deep dyslexia simulation, shallow attractor basinsat the semantic level were produced by lesions to the vision-to-semanticsconnections; thus some visual errors may be predicted without implicatingdamage to the visual input layer directly.

Plaut and Shallice (1993a) readily admit that the simulation was not de-signed to capture all aspects of the optic aphasic disorder, but rather to at-tempt, for the link between visual object and linguistic processing, an exer-cise similar to that performed for deep dyslexia in mapping orthographic to


semantic processing. For the purposes of the present account, our focus willbe on the sufficiency of the simulation to account for optic aphasic symptomsin one patient. The patient, AG, whom we describe here, is optic aphasic.More properly, he is optic category-specific-anomic, for his deficit in namingto confrontation is limited to object names rather than to the naming of seenactions. In this paper we detail his performance on a range of tasks designedto test visual, visuo-semantic, semantic, and some naming abilities to confirmand delineate the nature of his impairment in the light of the various theoreti-cal proposals outlined here. We also speculate on why action naming maybe (relatively) spared in this patient and on his associated impairments onother tasks.

CASE REPORT

AG is a right-handed male, born in Spain in 1932. He has lived in Britainfor 32 years. He worked in a hospital laundry until his brain injury and con-tinues to do so. He is a Spanish speaker with very little English and waseducated for 3 years, in Spain, to the age of 9. In July 1989 he was admittedto the Royal Berkshire Hospital (Reading, U.K.). An unenhanced CT scanshowed a large irregular low-density area in the left occipital lobe consistentwith infarction. The etiology of the stroke cannot be clearly specified. Severalpotential contributory causes are indicated in his medical record. He wasdiagnosed diabetic in July 1989 (whether pre- or poststroke is unclear), andCT chest scan showed an enlarged heart. AG smoked more than 40 cigarettesand drank alcohol daily. His medical notes further report that following CVAhe reduced his alcohol intake but continued to smoke heavily. On admissionto the hospital he had a right homonymous hemianopsia and was disorientedin time, confused, and slow. All tests, both for general clinical assessmentand for the experimental investigations were conducted in his native lan-guage (Spanish) by one of the authors (L.M.). His memory appeared im-paired but there was no apparent language deficit. Wechsler Adult Intelli-gence Scale tests 5 months postlesion revealed a low-normal verbal IQ (87)and impaired performance IQ (48). He was disoriented in time, being unableto state the date or the year. Three months later he was still unable to givethe correct date or to remember the date of well known holidays such asChristmas or New Year. Other tasks of self-orientation in space and timewere performed normally (person, place, and right–left orientation). His se-lective time disorientation was undoubtedly caused by the CVA. We did notfollow up this deficit which has been reported for other optic aphasic patients(Lhermitte & Beauvois, 1973; Coslett & Saffran, 1989). Visual attention(Poppelreuter) was good and visual memory (a Spanish simplified versionof the Benton Visual Retention Test) relatively good (11/15).

AG’s spontaneous speech was normal in its general characteristics (articu-

OPTIC APHASIA 189

lation, intonation, syntax, semantics, and pragmatics). The Boston Diagnos-tic Aphasia Examination (Goodglass & Kaplan, 1983; Spanish standardiza-tion by Garcia-Albea and Sanchez-Bernardos, 1986) revealed normalperformance on auditory tests (naming to an auditory definition; auditorycomprehension and repetition of any sort of verbal stimuli). When asked todescribe the BDAE Cookie Theft Picture he was hesitant and his descriptionwas empty of content and full of general terms. These tests of language weregiven 5 months postonset.

Reading deficits are apparent in all optic aphasics (see Table 1). Withinhis very limited literacy achievements (3 years of formal schooling) AGdemonstrated alexia without agraphia; he could write to dictation and sponta-neously; he could not read any written item, nor understand or copy writtenmaterial. However, he was able to match written words and nonwords. Thematching task was presented twice, at an 18-month interval. On first testing(9 months postonset), he was better at matching spoken targets to writtenletter strings than written targets to written letter strings. In each case he wasasked to point to one of five possible matches. The second assessment (Octo-ber 1991), using a larger set of words and nonwords, showed an improvementin AG’s visual matching (87% correct), with word length affecting his per-formance. On this second test, the modality-specific matching deficit was nolonger significant.

AG had marked difficulty naming to visual presentation when the stimuliwere objects, geometric shapes, colors, and body parts. He could name onlythe five human actions (BDAE, Card 3).

Given his performance on the BDAE, a further visual scene was presentedfor AG to describe (7 months postonset). The purpose was to draw a compari-son with his spontaneous speech (‘‘tell me about your job’’). AG spoke atotal of 523 words in 5 min of spontaneous conversation about his work and411 words in the 5-min description of the picture. He showed mild word-finding difficulties (twice) and semantic paraphasias (once) in spontaneousspeech. However, in the visual description task these problems became moremarked. He had word finding difficulties on 47 occasions (hesitations andcircumlocutions) and he uttered 18 semantic paraphasias. All these lattererrors were related to nouns (e.g., ‘‘(she) is on a ladder, no . . . I hadn’tnoticed the wheels, one of those cochitos’’. (Cochito is a neologistic diminu-tive of the normal Spanish diminutive for car, cochecito; he may have beenattempting to rename a bicycle as a very small car with only two wheels).He also made four gender confusions and four neologisms in the visual de-scription task.

The comparison between a spontaneous description of an event (‘‘tell meabout your job’’), which is not visual, and of a visual event (the picture)helps to confirm that AG’s failure to name drawings on formal examinationreflected specific problems with visual presentation, whether these were for-


mally or less formally presented, whether they were rich in visual contextor relatively poor, and whether specific conversational registers were or werenot engaged.

EXPERIMENTAL INVESTIGATIONS

Most of the experimental investigations were performed between March1990 and October 1991, during which time AG’s condition was stable. Afew tests (especially see Section 7 below) were conducted in September1992. Where this occurred it is indicated in the report of the test.

The first quantitative tests to be reported were intended to confirm thespecificity of AG’s impairment in object naming: to what extent was it spe-cific to visual presentation and to what extent was naming, rather than otheractions, implicated? These tests delineate the extent to which the syndromelabel of optic aphasia fitted AG.

1. Naming and Gesturing in Different Modalities (Table 2)

1.1.* Vision, Naming to Spoken Description, and Naming to Touch

Twenty-four objects (set A) were presented under three conditions fornaming: (1) visual presentation of the object, (2) spoken definition of theobject, and (3) tactile (blindfold) presentation of the object.

A further set of 24 objects (set B) were presented, again in the three differ-ent modality conditions, but in this case, a gestural response was required(‘‘Show me what you do with this’’).

The items from both sets were presented in random order for each of thethree sensory modality presentation conditions. There was an interval of atleast 6 weeks between one presentation condition and another both for nam-

TABLE 2Naming and Gesturing across Three Presentation Modalities:

AG’s Performance (% Correct), 24 Items in Each Set

Naming GesturingSet A Set B

Visual presentation (first test) 45.8 75Spoken presentation 100 100Tactile presentation 91.6 87.5

Set B Set A

Visual presentation (second test) 37.5 75

Note. Sets A/B visual presentation: naming set A–gesturing setB, z 5 2.08, p , .05; naming set B–gesturing set B, z 5 2.7,p , .01; naming set A–gesturing set A, z 5 2.14, p , .05. SetB visual vs. tactual modality of presentation: naming, McNemarχ2 5 8.63, p , .01; gesturing, McNemar χ2 5 .16, ns.

OPTIC APHASIA 191

ing and gesturing. Finally, 10 weeks after the conclusion of this task, set Awas presented for a gestural response and set B was presented for a namingresponse. This second part of the present task was administered only in thevisual modality. The items presented in both sets, and examples of AG’sresponses are shown in Appendix A.

AG showed a visual confrontation naming deficit, with preservation ofgestural responses to visual confrontation (z 5 2.08, p , .05). Naming toauditory definition was perfect and performance with tactually presented ob-jects was very good. AG’s naming deficit on visual confrontation was notconfined to a limited object category.

1.2. Naming Environmental Sounds and Musical Instruments

Some objects and object classes can be defined by their characteristic noiseor sound as well as by their look or feel. AG was presented with a range ofrecorded characteristic object–sounds for naming. On a separate occasion,the same objects were presented as photographs to be named. Of seven envi-ronmental sounds, AG made one error of omission (hand clap–‘‘don’tknow’’) but correctly named paper (crumpling), a baby (crying), telephone(ringing), a whistle, keys ( jangling), and glass (breaking). He correctlynamed guitar, flute, piano, violin, drum, and trumpet from their sounds. How-ever, when these objects were presented pictorially he could only name two(piano and trumpet).

AG was clearly optic aphasic in the strict sense of the term: simple con-frontation tests show that his naming deficit was evident only for visual pre-sentation and there was no apparent sign of difficulty with response modesother than naming. Moreover, no object category specificity was apparentin his naming failures.

2. Visual Processing and Access to Semantics from Degradedor Partial Visual Stimuli

2.1. Data Related to AG’s Processing of Visual Form

The first stage in the processing of visual form is to establish a robuststructural representation. What is contentious is the extent to which this stagehas embedded within it knowledge of specific exemplars and categorieswithin the visual world (see Chertkow, Bub, and Caplan (1992), for a discus-sion of this point). In these tests we take the view that two levels of visualmatching may be usefully distinguished. One, identity matching, requiresthat the viewer construct a stable representation of an object from availablevisual information that enables a form match to be made to a target differingin orientation and/or size from the depicted object. This task tests the integ-rity of structural representation processes. By contrast, exemplar matchingrequires semantic memory to inform the matching process, for in this casethe target is a different example of the same category as the object and is


FIG. 1. Examples of identity (top) and example (bottom) matching.

known as such through categorical knowledge of the world. In Fig. 1 thesetwo types of match are shown.

If performance on these two tests can be shown to dissociate, we wouldhave grounds for inferring a cleavage between structural representations thatdo not require semantic input directly and those that do; essentially betweenstructural representations and access to semantic representations from visualstructural descriptions.

These tests use degraded stimuli in order to introduce difficulty (sensitiv-ity) to the matching task in a patient with a suspected problem in analyzingvisual objects. While there are motivated means for degrading stimuli intospecific fragment types, reflecting different aspects of local object informa-tion in pictures (Biederman, 1987), our intention here was to ensure that theviewer was required to ‘‘fill-in’’ a number of local details from incomplete

OPTIC APHASIA 193

lines. Thus the fragmentary pictures were produced by hand, deleting partsof standard line drawings.

2.11. Identity matching from line fragments. Fourteen sets of items, simi-lar to those shown in Fig. 1 were presented. In each case the correct matchwas to an identical form at the top of the card. The target was always differentin lateral orientation and the fragments of target and match were dissimilar.The foil was always similar to the target in size, disposition, number, andcomplexity of line fragments. AG made two errors on this task (axe and batwere wrongly matched). Seven matched Spanish control subjects (mean age,55.5 years), with less than 5 years of formal education, made no errors.

2.12. Exemplar matching from line fragments. This test was similar tothat described above, but matches were to visually different examples of thesame category. AG made 8/14 errors on this test. From all seven controlsubjects a total of 3 errors was obtained.

This visual matching task was performed at or near ceiling by controls.AG’s two errors on the identity matching task did not put him out of rangeand no firm conclusion can be drawn from this comparison. However, forexemplar matching, AG’s performance was at chance and out of range ofcontrols. We conclude that, while AG could process fragmented forms suffi-ciently well to match on the basis of form, his ability to use semantic knowl-edge to inform this match (exemplar matching) was very limited.

2.2. Integrity of Visual Object Recognition Processes

Warrington (1984) has developed a number of tests of integrity of visualobject recognition processes. One (Test 3 from the VOSP; Warrington &James, 1991) requires the discrimination (identification) of an object silhou-ette from an unfamiliar orientation among foil silhouettes. The followinginstructions are given: ‘‘One of these four shapes is a silhouette drawing ofa real object, the others are all nonsense shapes. I want you to point to thereal object.’’ Twenty sets of items were presented. On this task, AG recog-nized 10 of 20 objects correctly. Published patient group norms are 17.7/20(SD 5 2.1) and 16.2/20 (SD 5 3.0) for left-hemisphere and right-hemispherepatients, respectively (Warrington & James, 1991). For letter forms, AG wasperfect (20/20) at identifying (naming) from presented fragments.

AG achieved stable structural descriptions (identity matching) from de-graded visual inputs, yet was unable use this information to access semanticknowledge (inability to perform exemplar matches). He had severe difficultycorrectly identifying silhouettes from odd angles. This could mean that hehas an impairment in achieving a ‘‘purely’’ visual structural description,since structural descriptions must be viewpoint-invariant. However, it ap-pears from systematic experimental studies with this silhouette material(Warrington & James, 1986) that a stable visually based description of anobject comprises a range of features, some of which may be obscured by


specific orientations: objects have a characteristic ‘‘fingerprint’’ of such fea-tures and sensitivity to rotation. If part of an object is obscured because ofthe angle of view, the viewer must try to ‘‘fill in’’ the missing part fromsemantic memory. Thus, good performance on the silhouette test requiresthe integrity of both visuo-structural and structuo-semantic processes, whiledifficulty with the task could be due to visuo-structural impairment, or toimpairment in visually specified semantic representations, or to a discon-nection between these processes. This point is explored further in tests onAG’s imagery skills (tests 2.31 and 2.32 below).

2.3. Imagery and Semantic Access from Vision

Most people can generate and consult images effectively; they can makejudgements of likeness, relative shape/size of parts of a named object, andso forth. In other words, they can use a semantic description, derived fromthe spoken name, to generate, address, and process a structural description.In the following tests we assess AG’s ability to do this: the rationale is thatthese tests require the generation of a stable structural representation froma semantic specification, just as exemplar and silhouette matching (tests 2.12,2.2) require effective access of a semantic specification from a structuraldescription.

AG’s imagery skills were assessed as follows:2.31.* The Tails test. This was derived and extended from Farah, Ham-

mond, Levine, and Calvanio (1988), who cite tests by Kosslyn (1975) as thesource of the idea. There were three conditions to the task. In each one thesame question was asked: ‘‘Is the tail of this animal long or short in relationto its body?’’ For the name condition, where just the name of the animal isgiven, the visual specification of the animal has to be derived from semanticmemory. For the pictorial condition, detailed line drawings correspondingto the names given in the first condition were shown. For these stimuli, anachieved visual structural description could support the judgement. In thetail masked condition the same animal drawings were shown but with thetails masked. Now the question addresses the ability to derive visual imageryindirectly from visual perception. It is necessary for the visual structuraldescription (complete except for the tail) to interface with knowledge of theanimal derived from semantic memory in order to generate an informativeimage and answer the question.

On verbal presentation, AG gave 17/20 correct answers and for the 3 otheranswers said that the tail was ‘‘the right size for the body of the animal’’(e.g., cow: ‘‘It’s the normal size for its body, but it is very thin’’). This givesa score of 85% correct by the strictest criterion, but with no errors. Whilehe was 95% correct for full visual presentation, he obtained a score of only60% for the masked-tail condition. This is not significantly different thanthe score that would be predicted by guessing (errors: rat, squirrel, mouse,kangaroo, deer, elephant, bison, cow). The difference between AG’s perfor-mance on this last condition and that of three tested controls was significant.

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Three Spanish-born people who had lived in Britain for at least 20 yearsserved as controls for this study (as for those reported below). Their agesranged from 49 to 62 years and they were, in educational attainment, similarto AG. The range of control performance on this condition was 95–100%correct.

2.32.* The Heads test. Riddoch and Humphreys (1987) developed a testwhich requires the patient to match on the basis of parts of a stimulus. Inthe Heads test, an animal head appears at the top of a card on which arefour other ‘‘bodies.’’ The patient matches the head to the appropriate body.The task cannot be performed on the basis of local (e.g., continuity of line)information, for heads on the stimulus cards are enlarged compared to bodies.Moreover, head and body cannot be seen in the same single glimpse; theyrequire, at least, a displacement transformation (a ‘‘blink transform’’; seeRiddoch, 1990). Thirty such cards were presented to AG who was asked topoint to the body which ‘‘goes with’’ the head at the top of the card.

AG was 73% correct (23/30; errors included squirrel (body)–mouse(head); seahorse–duck; monkey–lion/pig; kangaroo–tortoise; donkey–cow;deer–goat; seal–sheep). The Riddoch and Humphreys controls scored be-tween 26/30 and 30/30 (mean 94%). Thus, AG was below the normal range,though not as impaired as some agnosic patients on this test. His errors weregenerally ‘‘semantic’’: they usually respected the semantic category of thematch, sometimes even such aspects as size, use, and domesticity. By con-trast, it seemed to us unlikely that these were ‘‘visually’’ based errors. Thesewe would have predicted to have crossed categorical boundaries to a moremarked extent. Both these tests involve stimuli which have been ‘‘cut.’’ Itis possible that this had a particularly deleterious effect on AG (a perceptualparsing problem). A different version of the Tails test takes account of thispossibility.

2.33.* The Tails test: Front view version. Typical front or three-quarterviews of 19 animals (from the 20 presented in the Tails test) were placedin front of AG, one at a time. The tail was naturally occluded by the position-ing of the animal and AG’s task was to indicate if its size was long or shortin relation to the animal’s body. While controls were 89% correct (17–19/19), AG was 53% correct (10/19) (errors: rat, squirrel, mouse, cat, goat,zebra, cow, hare, spaniel dog). AG’s poor performance here reprises that onthe Silhouette test (2.2 above).

2.4. Summary: Tests of Access to Semantics from (Degraded) VisualInputs and of Imagery Ability (Generating Structural and SemanticDescriptions for Inspection)

In addition to a limited deficit in accessing semantics from fragmentaryvisual input and in interpreting unfamiliar silhouette views, AG demon-strated a specific imagery problem. This was circumscribed—it did not occurfor spoken names or for fully specified pictures, but only when the visual


stimulus was incomplete and required semantic support. In this context it isworth noting that JB, the ‘‘semantic access’’ agnosic/optic aphasic describedby Riddoch and Humphreys (1987), was more impaired than AG at this typeof test. For example JB was at chance at the Heads test, whereas AG showeda very mild deficit.

3. Access to Semantics: Nondegraded Visual Inputs

We have deduced that AG appeared to have intact skills of visual objectanalysis at the level of structural description, but could not readily achievea semantic representation from masked or degraded stimuli or from an unfa-miliar silhouette viewpoint. We assume that this was because interpretationof such stimuli requires some support from semantic structures, and thataccess to these was impaired. However, this has been shown only for de-graded visual stimuli (silhouettes included) and was inferred from his patternof dissociated performance on the Tails task. Did AG show evidence of im-paired semantic access from vision when inputs were not degraded? That is,how good was his semantic access from pictures of objects?

3.1.* Pyramids and Palm Trees: Picture Version

This ‘‘odd-man-out’’ test assesses real-world associative knowledge. Thetestee matches a target (spoken, written, or pictured) to one of two possibleitems. The correct item is the closer associate. For example, the target PYRA-MID should be matched to a PALM TREE rather than a PINE TREE. (How-ard & Patterson, 1988). There are 52 test triads. In the picture version of thetask, the target item appears at the top of the cards, with a choice of twopictures below it. AG pointed to the appropriate member of the picture pair.His performance (43 correct responses (82.7%)) was within range of 10 con-trols. These controls were closely matched to AG for culture (Spanish-born),for level of education (2–6 years), and for age (50–69 years). The mean oftheir correct responses was 46.3 (89.0%) (SD 5 3.03).

3.2.* Free Sorting of Pictures

Ninety line-drawn pictures of animals, food, drinks, musical instruments,and clothes were presented in random order for AG to sort freely into catego-ries. This open-ended, descriptive task gave AG the opportunity to use visual(‘‘it looks like . . .’’) or conceptual categories (‘‘it’s a . . .’’). He used fivecategories: land animals, sea animals, musical instruments, clothes, food anddrink. He made three errors (a kettle drum and a handkerchief were includedin the ‘‘food and drink’’ group and a seahorse was placed with the landanimals. Two pictures (of drinks) were put aside (possibly to start a newcategory). These were not counted as errors.

These tests suggested that AG could access semantic representations well,though not perfectly, when the visual material was not degraded. The follow-

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ing tests further probed his semantic access from vision and contrasted itwith that for names of objects.

3.3.* Answering (Visual) Questions about Pictures of Objects andNamed Objects

AG was asked a series of questions about 26 line drawings of objects. Allthe questions concerned their visual and concrete aspects (e.g., ‘‘What is itmade of? How large is it?’’). An average of eight questions were asked foreach object. After answering these questions, AG was asked to name thedrawing. The task was repeated 6 weeks later, but this time the object name,not the picture, was given (in Spanish).

AG’s responses were not sensitive to modality (visual presentation, 88%correct responses; auditory presentation, 91% correct responses. However,significantly more words were produced spontaneously when the item wasnamed than when the picture was presented (z 5 6; p , .001).

3.4.* Free Descriptions of Pictured and Named Objects

The previous task showed that AG was equally accurate in answeringquestions about pictures and spoken words though he was not equally fluentin both modalities. This task was designed to explore the capacity of thepatient to describe spontaneously familiar objects which were visually andauditorially presented. This type of task can be sensitive to problems in se-mantic specifications (see, e.g., Funnell & Sheridan, 1992). AG was notasked to name the picture and was encouraged to describe it. Twenty picturedobjects were shown. The examiner made the same general request (‘‘Canyou describe this? You needn’t say its name . . .’’) for each picture. Tenitems required a predominantly visual description (e.g., flower), while 10were predominantly functional (e.g., scissors). The same stimuli were pre-sented orally (‘‘Please describe a flower.’’) In a first session, half of the 20items in each modality were presented; order of presentation was reversedin the second session, 6 weeks later. AG’s descriptions, judged by two Span-ish people who did not know the stimuli, were identified 60% of times fromthe visual description and 95% from oral description (z 5 2.65; p , .01).Visual confrontation descriptions were often accompanied by gesturing (e.g.,playing a piano) and/or pointing to a similar exemplar which was present inthe room (e.g., an armchair). These were (naturally) not captured by writtentranscription of verbal responses. AG produced only 309 words (controlmean 5 707 words) when asked for a definition on visual confrontation; heproduced 901 words when asked to describe spoken words. Examples of hisoral and visual descriptions are shown in Appendix B.

Exploring Semantic Processing: Sensitive Cross-Modal Tests

The tests in this section further explored AG’s ability to interrogate seman-tics from vision and from spoken description and directly addressed the pro-


posal that there may be multiple semantic systems (primarily a visual anda verbal system) which become disconnected in optic aphasia.

4.1. Picture–Word Matching (1)

Deficits in precision of specification of pictures from words may be partic-ularly apparent in tasks requiring the choice of one target among visuallyand semantically similar distractors. AG was asked to point to a picture ofa spoken named object from among a set of three. Foils included items se-mantically and perceptually similar to the target (e.g., target, line drawingof a TANGERINE; foils, grapefruit and orange; target, CHIPMUNK; foils,beaver and squirrel). AG made 9 correct responses for 10 tests. Three Span-ish control subjects (see Section 2.3 above) made one error each (90% cor-rect).

4.2. Picture–Word Matching (2)

A similar test of pointing to a named picture was given to AG 2 yearsafter that described above (September 1992). In this version, we attemptedto make the task yet more discriminating. Foils were chosen so that one setcomprised visually similar items, one set semantically similar items and oneset visually and semantically similar items to the target. There were 10 setswithin each condition. AG’s controls for this test were the seven Spanish-born elderly people reported in Section 2.11. For visually similar sets (n 510), AG made no errors; while one of the seven control subjects made oneerror. For semantically similar sets (n 5 10), AG made three errors, and oneof the control subjects made one error.

For visually and semantically similar sets (n 5 10), AG made three errorsand a total of four errors was made by the seven control subjects.

AG’s performance on the sets that contained some semantically similarfoils was therefore out of range of normal controls. However, it was not atchance (as was his performance on the incomplete Tails test and on exemplarmatching from fragments).1

4.3.* Pyramids and Palm Trees Test—Spoken Word–Picture Version

This test is similar to that described in 3.1, but a spoken word was thetarget which was matched to one of two pictures. The (52) items were thesame as those presented in the all-picture version. In the spoken word–pic-ture condition, the experimenter spoke the target name (in Spanish) and AGpointed to the appropriate member of the picture pair. His performance (44correct responses (84.6%)) is within range of 10 Spanish controls. The mean

1 We have indicated that the CVA may have been the result of several causes, includingdiabetes and heavy smoking. It is quite possible, since his lifestyle changed little after thestroke, that he suffered further cerebrovascular incidents. At all events, whether due to thesefactors or others, we should bear in mind that performance on this task may reflect somedeterioration in cognitive function 3 years after his initial stroke and 1 year after conclusionof earlier tests.

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of their correct responses was 46.7 (89.8%) (SD 5 3.16). These controlswere those used in the all-picture version of the test. AG made the sameconsistently wrong choice in the two versions of the Pyramids and PalmTrees test for six specific items. Controls made the same, consistent choices.These particular responses may well be culturally determined and showmarked differences from those of British subjects. We cannot conclude fromhis performance on Pyramids and Palm Trees tests that AG had impairedsemantic processing, although scores in this range, in an educated Britishsample of similar age, would suggest a clinical disorder.

The tests reported above (4.1 to 4.3) all showed a mild impairment inmatching pictures to words, with a possibly more pronounced impairmentin the most recent and demanding test (4.2). His errors were primarily seman-tic rather than visual. The degree of AG’s impairment was similar to thatreported for his ability to perform semantic matches within the visual modal-ity (3 to 3.3). Thus, these debilities cannot tell us if an access or a centralimpairment is indicated. A further test attempted, indirectly, to elucidate thispoint.

4.4.* Matching a Picture to a Spoken Proverb

If visual semantics becomes disconnected from other semantic systemswe might expect particular difficulty in understanding metaphor as a ‘‘su-pramodal’’ aspect of comprehension when pictures are presented. AG wasasked to match spoken proverbs to one of a set of four pictures. The foilsincluded a literal representation of the proverb. One example illustrated theSpanish proverb ‘‘A bird in the hand . . .’’ The correct picture match wasof a man happily driving his cheap car past a showroom of expensive cars.The foils included a man feeding birds from his hand, wind blowing a moneynote from the hand of a standing man, and, finally, a literal depiction of theSpanish proverb. The patient made only one error for six such tested proverbs(within range of three controls). AG had no apparent deficit in accessingmetaphorical meaning from visual inputs and matching to a spoken phrase.

4.5.* Knowledge of Visual Aspects of Meaning: Functional Semanticsfrom Pictures

If a visual semantic system and a nonvisual semantic system each storedifferent aspects of meaning and become disconnected we might expect thatit would be difficult to access information about those aspects that are notintrinsic to (delivered by) visual–semantic representations. AG was askedto classify pictures of three categories of object by function: these were as-pects of meaning that are not visibly apparent and may possibly not be storedin a visual–semantic system. The categories presented were animals (as‘‘dangerous’’ and ‘‘tame’’); clothes (as ‘‘washable’’ and ‘‘nonwashable’’)and drinks (as ‘‘suitable’’ and ‘‘nonsuitable’’ for small children). AG’s per-formance in this task (90% correct) was not significantly different from that


of 10 matched controls (100% correct). Forty-five pictures were presentedaltogether in this test.

4.6.* Describing and Guessing

Another aspect of disconnection between semantic systems might be ex-pected to affect pragmatic aspects of description and communication. To theextent that pictures must be effectively described to communicate their con-tent, any disconnection between visual and verbal semantic systems shouldaffect such linguistic, communicative skills. A visual task was designed totest pragmatic aspects of picture comprehension and description which tookthe form of a guessing game. AG was asked to describe in words a picturethat he had been given, so that the examiner would be able to pick thatprecise picture from (visible) similar foils which were seen by AG and theexaminer together. The picture set comprised 10 pairs of items differing intwo or three key details (e.g., a white three-shelved corner table containingornaments and a brown two-shelved square table with an ornament and atelephone). AG’s task was to choose one picture and provide a sufficientlydetailed description of it to allow the examiner to identify it from its verysimilar foil. Once a picture was guessed by the examiner, it was removedfrom the set along with its partner. AG employed 315 words, though only6% of them were key nouns. When the three Spanish controls performedthe task, they used a mean of 184 words, of which 20% were key descriptiveterms. AG made 12 semantic paraphasias (controls, 0–2). He used nonverbalstrategies to communicate what he was seeing (e.g., he gestured to signifylong hair or round earrings he saw on a female character). Three of the itemscontained human characters performing actions: for these, AG started bynaming the action (e.g., play, smile, look at, lie down, sit down, and standup) which provided a key to the following description. For example, onepair of pictures showed a naked baby lying on its back playing with its toesand a dressed baby lying on its back playing with a toy. AG described hischoice in the following way: ‘‘There he is, lying on the . . . that is very soft,better that way because the boy is playing, or may be she is playing, youcan’t say if it’s a boy. Playing, yes, like this [pointing to his toes throughhis shoes]. Well, you can see that it’s a fat one, here [pointing to his legs].’’Neither of the two key words (‘‘naked’’ and ‘‘toes’’) were named. Neverthe-less, the communicative adequacy of the description was clear. He focusedon the important distinctions, although he could not find the names for them.

4.7.* Visual Characteristics of Semantic Representations: Access toVisual and Functional Semantic Attributes through Verbal Description

Knowledge of objects can have functional and sensory aspects. Thus, alemon can be described as ‘‘a citrus fruit used in cooking’’ as well as ‘‘asmall yellow juicy fruit with a sharp flavor and a thickish skin that releaseszest when cut.’’ We tested AG’s ability to consult semantic memory from

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spoken functional and spoken visual descriptions. The task had three stages:(a) a pretest where AG was asked to name 13 realistically colored picturesof animals; (b) spoken descriptions rich in visual detail for naming (fromthe 13 visually presented items in the screening task); (c) spoken descriptionsrich in functional detail (chosen again from the 13 previously presenteditems; see Appendix C). There was a 6-week interval between the stages ofthe task. AG was unable to name any of the 13 pictures on confrontation.He gave 7 correct names (AG, 70%; three Spanish controls, 80%) when thevisual attributes were described and 8 correct names for functional descrip-tions (AG, 80%; controls, 90%). None of these differences were statisticallysignificant.

Summary: Probing Semantic Representations

AG was able to address semantic knowledge effectively and in detail. Heanswered questions about visual and functional properties of objects fromthe picture or the spoken name of the object. He used semantic knowledgeto describe objects in visual terms. Not only could he categorize picturedobjects but he also answered detailed questions about pictures on confronta-tion and, with effort, found ways to communicate what he saw in a discrimi-native fashion, using language and gesture. In none of these demanding taskswas he worse than matched controls in showing that he had adequate accessto semantic structures.

Nevertheless, there were some signs of weakness in his performance onsome of these tasks. His errors in free picture categorization and his answersto questions about the qualities of visually presented objects (3.3) were sug-gestive of a mild impairment. Furthermore, one of the word–picture match-ing tasks (4.2) showed AG to make more mistakes than normal in dis-criminating semantically similar objects. This latter test was, however,administered 1 year after other tests of semantic access: we cannot rule outdeterioration in his condition as a cause of failure on this task.

5. Colors

If a central semantic impairment were the source of the optic aphasic defi-cit, why should naming be the critically impaired process? One answer thatis often given is that the name of a concept demands finer semantic specifica-tion than matching, pointing, discriminating or even gesturing. Thus, de-menting patients have (among other symptoms) a characteristic anomia.However, to demonstrate that conditions for an impairment are sufficientdoes not entail that they are necessary. To inspect this claim in AG we offerevidence from tasks concerned with color (Table 3). In all these tasks, AGwas working in a known, limited domain. Color names in Spanish (as inEnglish) constitute a small and overlearned class of familiar, fairly shortsubstantive nouns. The problem of specification of one name from amongmany hundreds or thousands does not apply. Moreover, we could arrange


TABLE 3Colors: AG’s Percentage Accurate Performance on

Tasks of Color Processing

Visual object presentation: pointing responseColor matching (to swatch) 100 (10/10)Choosing the correctly colored picture 80 (16/20)

Spoken name of object: pointing responsePointing to a color on command 100 (10/10)‘‘Which is the red square?’’

Spoken name of object: spoken responseCompleting a sentence 100 (10/10)‘‘the sky is . . . ’’

Visual object presentation:Naming colors 11.5 (3/26)‘‘What color is this?’’

the control task, of pointing to a color, to comprise a similar number ofchoices as are available for the choice of a color word. Do parallel patternsof impairment and sparing occur for color naming and color pointing tasksas for object processing?

5.1.* Color Processing: Visual Confrontation

AG was unable to name any color on formal examination. As an isolatedimpairment, this could reflect functional disconnection (Beauvois & Saillant,1985), achromatopsia (Meadows, 1974), or a color lexicon impairment (Ox-bury, Oxbury, & Humphreys, 1969). To distinguish these possibilities, thefollowing tasks were presented: color matching, discriminating between cor-rectly and incorrectly colored line drawings, pointing to a named color, com-pleting a spoken sentence with a color name, and finally color naming forpresented color patches.

First, clinical tests of color vision (Ishihara test, Farnsworth–Munsell 100-hue test) were given. The Ishihara test was performed normally, while theFarnsworth–Munsell test showed a mild abnormality in color vision that wasnot confined to specific spectral components.2

AG had a severe difficulty only in the color naming task and a mild diffi-culty in pointing to the correctly colored item. Our interpretation of this mildpointing deficit was that it reflected strategic ‘‘mismanagement’’ of the task:AG attempted to name the line drawings of objects on confrontation beforepointing—his errors followed misnamings. He was 100% correct at pointingto a named color. The differences between conditions are sufficiently clear

2 AG made a total of 210 errors. 16% of normal controls made more than 100 errors. TheFarnsworth–Munsell is a sensitive test of color vision abnormality; all reviewed patients withcolor naming disturbances who had normal Ishihara performance are reported defective on theFarnsworth–Munsell test (Meadows, 1974; Beauvois & Saillant, 1985; Davidoff & Ostergaard,1984).

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to claim that AG is not agnosic for colors and that his color lexicon is unim-paired, while his performance on the Farnsworth–Munsell test suggests amild degree of hue-discrimination impairment, in line with such reports forother optic aphasic patients (see Table 1).

5.2.* Functional Colors

AG was asked questions relating to functional aspects of color, those as-pects of color not readily derived from verbal knowledge but only from real(visual) experience. If visual and verbal semantics are distinguishable anddissociated in AG, these are questions he should not be able to answer reli-ably, just as a person blind from birth would be unlikely to be able to answerall these questions correctly. Examples included: ‘‘What color does rice be-come if I add saffron to it?; What color will a blue shirt be after some hoursin a bleach bath?; How do I know, by sight, that a banana is rotten?’’. AGdemonstrated very accurate color naming under these conditions (90% cor-rect, his only ‘‘error’’ being a response of ‘‘white coffee color’’ instead of‘‘light brown’’ when asked ‘‘what color does coffee become when milk isadded?’’) The mean for three matched Spanish controls was 93%.

5.3. Personal Colors

It could perhaps be argued that functional color knowledge need not beacquired/represented in a solely visually based semantic system: aspects ofit could be learned indirectly. The same cannot be said for personal colors—the only way we can report on the color of (say) our front door is by interro-gating personal visual memories.

In this test we systematically investigated two modes of presentation (spo-ken names of objects and uncolored line drawings), two modes of response(naming the color of the object or choosing the appropriate color crayonfrom among 20) and two types of color knowledge in objects: associativecolor and personal color. Following De Vreese (1991), the objects chosento test for associative color knowledge were cherry, lettuce, lobster, handsaw, clouds, tree trunk, snow on a mountain top, carrot, banana, and cartire. The personal color objects were toothbrush, front door, comb, (wife’s)hair brush, car, slippers, bedroom curtains, nightable lamp, dog, and kitchenchairs. For associative colors in the visual presentation condition AG wasasked ‘‘What color is this?’’ and the experimenter pointed to the appropriateline drawing. For associative colors in the verbal presentation condition theexperimenter asked ‘‘what color is a . . . (name of object)?’’ For personalcolors in the visual presentation condition, AG was asked ‘‘You (your wife)have/has one of these, what color is it?’’ while the experimenter pointed toan appropriate line drawing. For personal colors in the spoken name presen-


TABLE 4Associative and Personal Colors: AG’s Naming and Pointing for Named Objects

and Drawings of Objects (% Correct)

Visual Verbal(object shown) (object named)

Pointing Naming Pointing Naming

Associative knowledge (verbal) 80 20 90 70–90(a) (b) (c) (d)

Personal color knowledge (visual) 80 30 90 80(e) (f) (g) (h)

Note. Errors: (a) Tree (gray), lobster (dark brown). (b) AG used only saturation termssuch as ‘‘dark, light, fairly dark’’ for eight objects. He named the color of the lettuce cor-rectly and produced the correct color for snow on the mountaintop (‘‘It’s all snowy, allwhite up there . . .’’). (c) Lobster (‘‘No color really . . . its between that (red) and that(brown) . . .’’). (d) Lobster (‘‘I don’t know what to call that color—it’s a dark color’’).For the tree he said ‘‘wood-color’’ and for the carrot, ‘‘carrot color’’ (‘‘color zanahoria’’).(e) Toothbrush (green instead of blue), front door (beige instead of brown). (f) Color namingwas random for seven objects. He named the colors of his bedroom curtains correctly (pinkand white), his car (white), and his wife’s hairbrush (green). (g) Toothbrush: he chose twocolors; blue and dark green. (h) Dog: ‘‘It was black, with a bit of brown and red . . . thatcolor isn’t here . . . ,’’ front door (‘‘It’s not dark or light . . . in between . . .’’).

tation condition, AG was asked ‘‘what color is your . . . (your wife’s) (nameof object)?’’ Table 4 shows the results of these tests.

This pattern of impairments and sparing allows us to conclude that:1. AG showed no significant distinction in performance reflecting two

sources of color knowledge—associative and personal.2. AG reliably discriminated color (choose the appropriate color) for both

named and drawn objects.3. AG showed a marked dissociation between naming the color of objects

on visual confrontation and on presentation of the spoken name.Since only color knowledge—a limited conceptual and nominal domain—

was interrogated here, it is unlikely that the naming failure was due to partic-ular difficulty in semantic specification of the required output.

6. Naming Tasks

What aspects of AG’s speech output were specifically compromised onvisual confrontation? Here we draw attention to object naming impairmentand action naming preservation.

6.1.* Naming Drawings

The tests used were the Boston Naming Test (BNT) and a set of 90 coloredpictures from The First Thousand Words (FTW) most used in different lan-

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TABLE 5Naming Line Drawings: AG (% Correct on Two Occasions)

November 1989 May 1990

BNT 31.7 36.7(19/60) (22/60)

FTW 43.3 45.5(39/90) (41/90)

Totala 38.7 42(58/150) (62/150)

a Test for differences between proportions; z 5 .72, ns.

guages (Cartwright & Avery, 1979) (Table 5). Thus all picture/words testedwere of high frequency in most speakers’ native language. This task waspresented twice, with a 5-month interval, to test for the transience of thedeficit.

The mean items correct for the 60-item version of the BNT is 53.7 (97%)for Spanish controls; AG’s score on the BNT was thus very low. The differ-ence in performance on the BNT and the FTW was nonsignificant (z 5 1.8).Moreover, the total score obtained on the two testing dates did not differ.Most errors were semantically related to the target; superordinates (camel—‘‘You can see that animal on TV films’’) or the use of the object (harp—‘‘That’s from old times, you can play music with it’’) were named on 43.5%(65/150) occasions. Perseverations were frequent but usually with correc-tions (tennis raquet—‘‘That’s for sitting [the previous item was a bench],no, no, to play, to play what do you call it? [correct gesture] to play tennis,it is a . . . [masc.] a . . . [fem.] how do you call it?’’). Some responses wereunclassifiable since the description, while correct, was nonspecific or tied topragmatic details (stethoscope—‘‘They have that there, where I work’’[Who are they?] ‘‘Doctors, they work with it.’’). Sometimes an item wasincorrectly named, but described appropriately (e.g., crown—‘‘That’s anumbrella’’ [gesture of setting something on the head with both hands] ‘‘andthe king and the queen wear it.’’).

For most items that were named correctly, the name was given after somedescription of action/use (canoe—‘‘It is useful if you are near the sea andyou can go fishing, it goes on the . . . it’s a canoe’’). Seventy-two percentof items which he successfully named were preceded by such conduitesd’approche.

6.2.* Naming Faces

Twelve photographs of well-known people were shown to AG in 1991:all of them were described correctly, and with appropriate distinguishingdetail, but only one (Mrs. Thatcher) was named (e.g., Neil Kinnock—‘‘La-


bour party, will be the master if he is elected.’’; Prince Charles—‘‘TheQueen . . . her son.’’).

6.31.* Naming actions. Action naming was more fully investigated, fol-lowing the impression that it was relatively spared in contrast to object nam-ing. In one test comprising simplified drawings of actions and fuller, morerealistic ones he correctly named 41 of 43 actions. (The range for the threeSpanish controls was 40–43). To explore further his action naming preserva-tion relative to object naming impairment, the following tasks, eliciting bothaction and object names, were given.

6.32. Action and object naming. (A) Pictures of objects: Thirty pictures ofobjects were presented. Two questions were asked: ‘‘What can you do withthis?’’ (AG, 66.6% correct; controls, 97% correct) and ‘‘What is its name?’’(AG, 26.6% correct; controls, 100% correct). The action/object naming differ-ence is statistically significant. (B) Pictures of actions: The same 30 items inan action context (drawings and photographs of people using the objects) weregiven and the corresponding questions were asked. For ‘‘What is s/he doing?’’AG was 96.6% correct. (The only action he did not name was ‘‘sleeping.’’ Hisresponse was ‘‘You cannot say what he is doing, he is in bed, peacefully.’’ AGnamed ‘‘sleeping’’ in several other occasions. Controls were 100% correct).To the second question: ‘‘What is the name of this object’’? AG was 63.3%correct (controls, 100% correct). AG’s naming performance is again signifi-cantly different for actions and objects (z 5 3.4; p , .01).

AG was better at answering questions based on depicted actions than thoseabout depicted objects. On no occasion was an item named as an isolatedobject and not named in an action context. By contrast, 11 items were namedin the action context condition only (i.e., in part B of the test; bed, razor,telephone, paintbrush, pram, glass, TV, umbrella, cigarette, needle, andtoothbrush). For 10 of 11 items the action name preceded the object name.For isolated object naming, semantic errors were often followed by correctaction naming or other correct responses (e.g., a pair of skis—‘‘They areroller skates, a sort of those skates . . . to ski.’’; a train—‘‘This is a lorryto transport many things.’’).

6.33. Action and object naming: Actions without objects. AG was shown20 pictures depicting a character performing an action without any object(that is, miming an action). The questions asked were ‘‘What is s/he doing?’’(100% correct) and ‘‘What does s/he need to do that?’’ The patient named12 items (60% correct; controls, 95% correct). Eleven named items werepreceded by AG’s spoken action description (e.g., three men sitting; no visi-ble seat—‘‘They are talking, sitting there. What do they need to talk? ah,to sit down, chairs, really, you can’t see any.’’). In reply to action namingquestions AG named three objects spontaneously (spoon, belt, and poles).In the object naming part of the task, he named 19 actions spontaneously.

6.34. Naming objects through pantomime. In a live pantomime task, AGwas asked to respond to the experimenter’s general question ‘‘What am Idoing?’’ The 20 items were unambiguous with respect to the object that

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could be used in the action (e.g., playing the piano, guitar, violin; puttingon shoes, a necklace, a hat, etc.). However, only four action-types, eachrepresented by a single verb in Spanish (play, put on, make, and call) wereused. Thus successful search for the correct action name would not necessar-ily cue the appropriate object names. Under these conditions, AG named 15objects (75% correct; controls, 95%, z 5 1.8; ns).

6.35.* Action by the object. AG was shown six objects that performed anaction which was predominantly visual and inanimate (e.g., the light of atorch glaring on a mirror, a child’s game producing twinkling light, etc). Henamed them without hesitation. (A further demonstration, of reflected light,he could not name. We believe that this word was not in his vocabulary; hecould not generate it to spoken definition.)

Summary: Naming Objects and Actions

AG’s naming impairment was specific to seen objects with relative preser-vation of pictured action naming. Action naming when an isolated objectwas presented was 66.6% correct. Object naming in an action context was63.3% correct and objects could even be named when they were absent, ifan action context was given (60% correct). This suggests a particular pathto naming under action context conditions which supports naming more ef-fectively than confrontation conditions—for both actions and objects. Visualevents may activate action concepts which may, in turn, lead to the objectname. This even seems to be effective when the action name itself is notspecific (6.33).

Covert cuing of actions by gesture is not likely to be responsible for AG’saction naming. Inanimate, purely visual actions cannot be identified by cuesbased on gesture, yet AG named such actions appropriately (6.35). Ellis andYoung (1988) suggest an account of optic aphasia in terms of different routesto naming and to gesture from semantic knowledge of objects and from struc-tural aspects of the perception of objects, respectively. On their account itmight be possible for actions to cue names via (covert) gestures appropriateto the seen object/scene but not, directly, for seen actions to afford names.On their account, seen events can afford gestures but not names—not evenaction names.

We discuss the action/object naming dissociation observed here in moredetail under General Discussion.

Interim Conclusion and Interpretation: Are AG’s Demonstrated DeficitsSufficient for Optic Aphasia?

AG has a deficit in naming pictures, other than pictured actions (whichcan cue his object naming). He also appears to have mild vision-to-semanticsaccess problems, despite reliable achievement of structural visual representa-tions from visual inputs and indirectly, from semantic inputs—see 2.3. Whilesome of his performance on tasks that demand semantic knowledge might


suggest a more central disorder, of specificity of semantic representations,we have been unable to find any indication of a deficit that is limited to suchcentral impairment, whether a disconnection between semantic systems ora disturbance within semantic representations. Moreover, the general pictureof semantic performance in AG is unimpaired (Pyramids and Palm Trees isa sensitive test of semantic associations). Visual inputs appear to be particu-larly compromised—but very mildly. AG’s deficit is far less marked thanthat of JB (Riddoch & Humphreys, 1987). That patient was at chance onthe Heads test (2.33), as we have already remarked, while in comparison totheir well-known integrative agnosic patient, HJA (Riddoch & Humphreys,1987), AG’s visual deficits are not apparent at all. AG can identify letterforms from fragments, can make reliable distinctions on pictures and so forth.Why then should AG’s confrontation naming for objects be so impaired?

In our view, the most convincing theoretical position at this stage is thatof Farah (1990), who suggests that superadditivity within an interactive se-quence of stages from vision to naming could produce optic aphasia as afunction of a mild presemantic and a mild postsemantic impairment. Wehave demonstrated a possible mild presemantic impairment. We have shownhis naming of actions to be unimpaired. Our next step, therefore, is to explorethe possibility of a postsemantic object-naming impairment more closely.

7. Naming: A Postsemantic Impairment

While AG shows a clear dissociation in naming to visual confrontationthat is sensitive to whether actions or objects are presented, it is not clearto what extent his naming difficulties may involve postsemantic damage,irrespective of type of input (i.e., a postsemantic deficit in Farah’s theoreticalscheme). Gainotti, Silveri, Villa, and Miceli (1981, 1986) described twogroups of patients in whom a relatively pure anomia was the presentingsymptom (the modality-specific anomias were not considered). One groupshowed some difficulties in auditory comprehension, the other no demonstra-ble difficulty in auditory comprehension. The first group tended to producesemantic naming errors, without correction or hesitation, while the secondgroup was sensitive to the sound structure of the ‘‘unavailable’’ word butcould not utter it. These patients occasionally made semantic errors too, butwere aware of the errors that they made and attempted often to correct them.An interpretation of these two patterns is that members of the first grouphave problems in the semantic specification of names, the those of secondonly in the activation/retrieval of the phonological form itself. AG’s visualnaming difficulties seemed more characteristic of the second than the firstgroup. Two experimental tasks may be interpreted to show evidence of a‘‘postsemantic’’ anomia, affecting the output route from the semantic repre-sentation to the phonological word-form. Neither would be conclusive inlocating the deficit at this postsemantic site, but should we demonstrate defi-cits in these tasks, since none were demonstrated for other semantic tasks,we shall at least have more faith in this possibility.

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TABLE 6Number of Items Reported in 1 min (without Repetition) to

Spoken Cue: AG and Matched Control Subjects

AG C1 C2 C3 C4

Kitchen objects 7 18 19 17 13Words that start with ‘‘P’’ 4 12 10 10 18Actions performed by children 4 9 15 11 14Actions performed outdoors 5 13 13 9 18

5 13 13 9 18

7.1.* Verbal Fluency to a Cue

AG was not particularly fluent in describing scenes (3.4). This (mild) dys-fluency was investigated further, through tasks that required naming to a cue(such as animal names or words that begin with D). The number of wordsproduced within a unit time that fit the category label without repetition isthe index of verbal fluency. Measured in this way, the fluency task can beconsidered an index of the integrity and efficiency of semantic-output map-pings (‘‘postsemantic activation’’), at least in a patient with no anterior le-sions and no functional indication of frontal deficit. AG was asked to name(in Spanish) ‘‘as many names as possible’’ in 1 min, without repetition, tofour cue categories. The categories were illustrated by examples, and practicewas given before his timed responses were taken. Table 6 shows the numberof AGs responses, without repetition, to each category cue. It also showsthe performance of four Spanish-speaking control subjects, matched to AGfor general background and age. Control 1 is AG’s wife.

The overall mean of controls, across all four categories, was 13.56 itemsin 1 min. AG was out of range of controls on all cue conditions. He madeno errors in this task, only repetitions. He was slow because he often showedexplicit word-finding difficulties. Although his picture naming was sensitiveto word class, these fluency tests suggest that both object-names and action-names were equally affected under fluency generation conditions.

7.2. Cuing and Miscuing Naming Responses

Table 6 shows that giving a sound cue (‘‘starts with p’’) did not improveAG’s fluency. However, to what extent did phonemic cues help him in nam-ing objects on presentation? The role of phonemic cuing may be importantin locating the functional impairment in (nonmodality specific) anomia(Kay & Ellis, 1987). For example, where a correct phonemic cue improvesnaming, that suggests that the naming deficit may reflect impaired phonologi-cal structures/access processes. However, if a patient can be induced to nameitems wrongly because of misleading phonemic cue (e.g., T (‘‘tiger’’) . . .for ,LION.) that might suggest a semantic disorder, since the patient isnot discriminating items with similar semantic forms (Howard & Orchard-


Lisle, 1984). For picture presentation, of course, semantic underspecificationcould arise because visual access is impaired. Thus evidence that AG maybe misled by semantic cues in picture naming cannot, on its own, be takento support a central representational deficit.

7.21. Correct and incorrect cues. Thirty pictures were presented that AGwas unable to name without cues. Half of them were presented again witha correct phonemic cue (‘‘it starts with . . . ,initial phoneme.’’) and halfwith a misleading cue, where the initial sound was of a semantically similaritem. For the 15 correctly cued items, the phonemic cue led to the correctname 9/15 times. He was still unable to name four items and misnamed oneother. For the 15 miscued items, he was misled into naming the semanticallysimilar word 8/15 times, and named the correct word four times. For theremaining pictures he failed to name (twice) and made one other namingerror.

7.22. Cuing BNT items. In mid 1992, AG was again presented with 60pictures to name from the BNT list (see 6.1) which he had been asked toname 18 months earlier. He named 14 correctly. For the 46 incorrect itemsa semantic cue (category and description) was given as each picture wasreshown. He now named 8 more items correctly. Finally, for the remaining38 items a phonemic cue (initial phoneme) was given. Just 3 more itemswere correctly named. As in earlier tests, where he was unable to name anitem correctly, he nevertheless often gave more or less detailed semanticdescriptions of the object.

In this test, then, AG was helped both by semantic and phonological cuesto name pictures. However, it should be noted that his uncued performancewas worse on this occasion than on the earlier testing (see Table 5) and cuingonly brought him within range of his earlier, uncued performance.

Summary: Output Effects in AG’s Naming?

The rationale for testing AG’s verbal fluency was similar to that for look-ing for effects of phonemic cuing. In both cases, we were exploring thepossibility of postsemantic (output) problems. The results of these tests canbe interpreted to indicate such postsemantic naming difficulties; albeit notin a conclusive fashion. AG’s ability to generate names to a single semanticor phonemic cue was poor and showed no advantage for action over objectterms. This might suggest a problem in activating the full phonemic formof a word from its semantic specification. When cued, AG was somewhathelped in finding a picture name.

These cued picture naming tasks, which were given nearly 2 years afterthe original investigation, suggested some deterioration over this periodwhich makes definitive interpretation problematic. Both semantic and phone-mic cues helped him to produce the appropriate word on visual confrontation:but not very much. This negative finding—cuing had little effect on AG’s

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visual confrontation naming—together with his generalized mild fluency im-pairment might be interpreted to mean that the activation of the phonologicalword form was particularly recalcitrant.

DISCUSSION

What functional lesion or lesions underlie AG’s optic aphasia? The sys-tematic report of AG presented here explored visual, semantic, and (to alesser extent) speech-output processes in relation to objects and actions inan attempt to locate the specific deficit or deficits that gave rise to his denseoptic anomia. We demonstrated some fragility in visual processing, whichcould be interpreted as a deficit in accessing semantic structures fromachieved visual–structural representations. There was an associated deficit inimagery processing. There was also some sign of weakness in verbal fluency.

Semantic Access Difficulties or Semantic Frailty?

None of the tests of semantic processing showed any clear sign of ‘‘cen-tral’’ semantic deficit nor of visual–verbal semantic dissociation. Some ac-counts of naming difficulties in patients stress that naming is characteristi-cally the task that requires the finest semantic specifications and thatmatching and gesture tasks are not sufficiently fine-grained to detect seman-tic anomalies. In the section on AG’s color processing, we showed that evenwhen we matched color processing tasks systematically for response diffi-culty (colored crayon choice and color name choice), AG was still specifi-cally impaired at naming colors of visually presented objects—whether suchcolor knowledge is acquired through personal knowledge, through verbal orlearned associations, or through functional, action-based knowledge derivedfrom his laundry work. From this point of view, then, AG may be consideredto have a well specified semantic system (or fully interconnected semanticsystems). An alternative account would point to the large number of semanticerrors that AG made in naming, to suggest fragility in some aspects of centralsemantic representations that affect both access and output. This interpreta-tion can, however, be countered by the finding that access difficulties, simu-lated in a connectionist model, can give rise quite easily to semantic errors(see below).

Disconnected Semantics in Partially Disconnected Hemispheres?

Coslett and Saffran (1989) resurrected Freund’s (1989) original accountof optic aphasia in terms of a dissociation between right hemisphere (RH)and left hemisphere (LH) processes, caused by a medial left occipital lesionin optic aphasic patients. This assumes that semantic representations areequally good in each hemisphere and that while the right hemisphere cansupport all manner of visual semantic tasks, the left alone supports naming.


Their patient, like AG, demonstrated intact semantic matching and categori-zation skills for pictures and for spoken words and, in addition, showed writ-ten word naming problems suggestive of ‘‘right hemisphere reading.’’ Theaccount that they offer for optic aphasia is very similar to that offered forpure alexia (Geschwind, 1965). The argument for cerebrally disconnectedsemantic systems for their patient, then, rests (as does ours) on demonstratedassociated deficits rather than anything else. We could not test AG’s readingeffectively because of his limited schooling, so cannot bring this evidenceto bear (but see the case description). However we do have evidence for AG,which Coslett and Saffran suggest is absent for their patient, that under cer-tain conditions visual access to semantics was not perfect.3 These conditions(see Section 2) do not immediately lend themselves to an explanation interms of hemispheric semantic disconnection. At present, while we acceptthe general notion that partial disconnection can provide an elegant explana-tion for some aspects of optic aphasia, AG alerts us to the possibility thatit may be access-paths to semantics that are differentially localized.

Furthermore, as Coslett and Saffran themselves point out, the discon-nection account predicts both pure alexia and optic aphasia: yet not all pa-tients (who can read) with lesions in this site have both sets of symptoms.

Is a Visual Access Deficit Enough?

Is an access deficit, however conceptualized, all that is required to produceoptic aphasia and to explain AG’s performance? Plaut and Shallice (1993a)show that a connectionist model of learned mappings between visual and(unitary but distributed) semantic representations, can, when the vision–semantic mappings are lesioned, generate error patterns representative ofoptic aphasic patients. They suggest, therefore, that a semantic access prob-lem is a necessary and sufficient condition for optic aphasia. Moreover, theirmodel, when lesioned, generates a pattern of errors similar to those observedfor AG. Furthermore, vision-to-semantics lesions, they suggest, leave ‘‘resid-ual semantic activity in the damaged network (able to) support quite reason-able performance on nonverbal tests of comprehension even when overt nam-ing is virtually abolished . . .’’ (p. 106). In principle, then, this model fitsAG’s pattern of performance well. It is, however, incomplete since the rela-tionship between access and output difficulties has not yet been explicated.AG has a verbal fluency deficit that is not sensitive to the same parameters(objects vs. actions) as his naming deficit. It is possible that such a general-ized fluency deficit, and a nonspecific effect of cuing as demonstrated inSection 7, might follow from the model, once output paths from the shallow

3 However, their report suggests that the patient has a mild problem in interpreting ‘‘unfamiliarviews,’’ although they choose to ignore this isolated visuo-semantic impairment (p. 1100,lines 12–16).

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semantic attractor basins formed by lesioning the visual–semantic access areinstantiated. However, it is also possible that this pattern might not emergeand that a semantic access account of optic aphasia, drafted on connectionistprinciples outlined by Plaut and Shallice, may provide a necessary, but possi-bly insufficient, cause for optic aphasia.

Pre- and Postsemantic Impairments?

Farah (1990) has suggested that mild impairments in pre- and postseman-tic transmission in an interactive vision–semantics–naming system workingin cascade are required. Though individually mild, the effects of functionallesions so located would be superadditive when visual confrontation namingis called for. AG shows mild fluency deficits—which we suggest can beconstrued as a deficit in postsemantic activation of words—even when novisual stimuli are presented (7.1). Together with a presemantic (mild) accessimpairment, his optic aphasia could be accounted for by Farah’s suggestion;however, it should be remembered that the effect of cues on AG’s picturenaming were inconclusive. More generally, AG’s output disorder is open toa number of interpretations other than those congruent with Farah’s hypoth-esis.

The main interpretive problem for optic aphasia (and for some other cen-tral neuropsychological disorders) is that it is still unclear to what extent avery mild and generalized lesion to a central semantic system, connected ina distributed fashion to input and output domains, might leave performanceintact on a range of apparent tests of semantic integrity and affect modality-specific input and output processes rather more. In contrast, the effects ofdamage to the peripheral processes are currently being effectively modeledand can be seen to produce quite specific impairments unforeseen by straight-forward serial modeling of discrete information processing stages.

Imagery and Visual Access

One paradoxically convincing aspect of Farah’s theory compared withother proposals (except, possibly, that of Plaut and Shallice) is that it suggeststhat the mildness of the access problem is crucial. AG’s visual access deficitswere apparent only on some very specific tests and not, for example, whenthe pictorial display contained the necessary information for semantic identi-fication.

AG’s ability to categorize and reflect upon visually presented material isgood, and always within normal range—even when ‘‘visual’’ rather than‘‘functional’’ aspects are the criterion for selection. In the Heads imagerytask AG (unlike the Riddoch and Humphreys case of ‘‘semantic access’’agnosia, JB) was not at chance—as long as all the necessary features couldbe viewed in one presentation. Only with masked or frontal presentationsfor the Tails test did a marked problem appear. Is this circumscribed problem


FIG. 2. A model of the proposed relations between visual and semantic processes.

in making imagery-based decisions on partial visual stimuli an indication ofa presemantic access impairment? We would like to argue that it could be, ifone conceptualizes the relationship between semantic representations, visualrecognition and imagery generation in the following way.

First, imagery generation requires an intact visual object recognition de-vice (VOR units in a visual object recognition system) which is characterisedby structural (visual) features. Second, VOR can be accessed directly fromvisual inputs or indirectly, from semantic specifications. The active represen-tation may be different, depending on the mode of activation. For example,the word TEAPOT probably activates a representation that supports a rangeof imagery tasks (‘‘is the handle longer than the spout? ‘‘Does the spout pointleft or right?’’ . . .) while the visual depiction of a teapot, though adequatelyrecognized, may not always be able to support these tasks (for instance, ifthe viewpoint of the teapot led to occlusion of the spout). Conversely, it maybe possible to perform some imagery operations on figures which have nosemantic representational status (nonsense figures); they ‘‘exist’’ solely asVOR-units.

Figure 2 shows this relationship diagrammatically. In AG, route S must beintact, for he can effectively address images derived from spoken names—whether these are of object-forms (Heads, Tails tests) or colors (personalcolors). We claim that there is a mild impairment in route V from vision tosemantics. It is mild because it does not prevent him performing a range ofvisual semantics tasks normally, when the stimulus conditions are reason-able. In order to perform imagery tasks on visually incomplete stimuli theV–S routes must operate recursively, with visual structure information andsemantic feature knowledge informing each other effectively until the correctidentification is made. A similar operation is required to identify silhouetteobjects from unfamiliar views.

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The masked Tails (and, to a lesser extent, the Heads) imagery tests cannotbe performed directly on the stimulus, for the relevant details are not repre-sented at the VOR stage. For most people, however, such partial representa-tions are sufficient to activate the appropriate semantic nodes (via V) andhence to effect indirect routing to appropriate imagery interrogation (via S).In AG the V route is not fully functional and so the appropriate unique object-concept is not reliably activated. Thus the indirect ‘‘support’’ reactivationfrom semantics to the VOR system (S route) will not operate reliably forhim either—at least, not when the material presented is visual.

Separate, unidirectional mappings between vision and semantics and be-tween semantics and vision may be required for further computer simulationsof these imagery effects. The Plaut and Shallice (1993a) model comprisessame-domain (semantic/clean-up pool) separable mappings, but no ‘‘top-down’’ route between semantics and vision.

Preserved Action Naming: Speculations

We have demonstrated in AG a dissociated aspect of naming performancethat has been mentioned anecdotally in some other patients but has not sofar been investigated in detail (see Table 1). AG can and does name seenactions well. He can do this when the actions are inanimate, so he cannotcue himself by covert imitation of seen gesture, and he can name actions inscenes where the object is absent. Beyond this, actions are often used to cuehimself with the (correct) names of the object; even when the action nameis itself nonspecific (PLAY (piano, guitar); see 6.34).

Could suboptimal activation of object-concepts (a mild deficit in semanticaccess from vision) lead to reasonable action naming in the absence of objectnaming? Hillis, Rapp, Romani, and Caramazza (1990), in developing theCaramazza et al. (1990) hypothesis, point out that a range of semantic tasks,including gesturing and categorization tasks, may be effected with incom-pletely specified semantic representations of seen objects. For example, inorder to correctly mime the peeling of a banana, it is not necessary to recog-nize all aspects of ‘‘bananahood’’—only those pertaining to skin thicknessand points of holding. However, we need to explain why action namingshould specifically be preserved under these suboptimal activation condi-tions. As far as we can determine, the Plaut and Shallice (1993a) simulationdoes not engender ‘‘action-for-object’’ errors, analogous to ‘‘concrete-for-abstract’’ errors in deep dyslexia. Jackendoff (1987) has pointed out that seenobjects and seen actions bear different relationships to semantic linguisticstructures: objects tend to have unique, defining, perceptual characteristicsthat can map directly onto the underlying semantic (linguistic) structures;actions tend to generality—their defining semantic features are rarely di-rectly given by the use of a particular object but are adduced from manyexamples using different objects. On this sort of account, action terms are


necessarily more abstract than object terms. Thus, on the face of it, actionsmight be predicted to be harder to name than objects, following the analogyfrom abstract/concrete word differences. However, this may be only an ap-parent paradox. For object semantics, abstract terms appear to comprisefewer features than concrete terms and are susceptible to lesion damage forthat reason (see, e.g., Plaut & Shallice, 1993b). Depth of representation, asimplied by Jackendoff, is not addressed by that level of modeling. To simu-late a system that captures Jackendoff’s insight, it may be necessary to posita ‘‘deeper’’ level of representation for action than object terms. Then, for aposited visual access deficit, it might follow that action terms are less likelyto suffer damage. Alternatively, Jackendoff’s proposals might be instantiatedcomputationally so that, for a specific action-term, there are multiple routesfrom vision to semantics. This may perhaps account for relative sparing ofaction terms in optic aphasia.

Following the Caramazza et al. notion of differential accessibility, per-ceived actions may be thought to have a privileged route for semantic–pho-nological activation. Action-terms may show resistance to damage when ac-cessed from perceptual inputs, because of the many ways (including, but notlimited to, action affordance by a visually presented object) in which a spe-cific action-term may be activated.

Whatever the mechanism of preferential activation for action than objectterms, there is no need to hypothesize specific grammatical-category deficitsin (postsemantic) phonological output in this case, only asymmetric patternsof activation for object concepts and for action concepts (following visualconfrontation), which then show grammatical category effects ‘‘down-stream’’ from the mild presemantic impairment. If we were to propose gram-matical-class-specific impairments at a postsemantic level for AG, in linewith the explanations for anomia proposed by Zingeser and Berndt (1988),that would not explain why the action/object difference was specific to seenevents in this case. Moreover, our single explicit test for naming actionsand objects where semantic criteria were more relaxed—the fluency task—showed no grammatical category sensitivity. AG generated action names toa cue as slowly as he generated object names (see Table 6).

CONCLUSION

We have demonstrated a large number of spared capacities and a fewisolated and mild impairments in a pure case of optic anomia, AG. Our testshighlight the following aspects: relatively normal semantic processing, amild fluency deficit, spared action naming from vision, with actions often‘‘cuing’’ the missing object name and a mild deficit in visual access to se-mantics, apparent only for ‘‘incomplete’’ visual stimuli and in imagery inter-rogation for such stimuli. The naming problems appeared for all object cate-gories and AG’s color processing problems closely echoed those for visualobject processing.

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Some models of optic aphasia, for example those that might claim thatsome central semantic processes are defective, are not yet sufficiently wellspecified to test against AG’s performance. We have, however, demonstratedno apparent difficulty in mapping visual to verbal knowledge where inputis not, itself, visual. Farah’s (1990) account, implicating superadditive mildpre- and postsemantic impairments to account for optic aphasia, fits this casereasonably well. The evidence for a mild access disorder is stronger thanthat for a corresponding and additional problem in the activation of thesound-form of names. To this extent, and bearing in mind that computationalsimulation to date has not implemented Farah’s hunch, AG’s visual namingperformance also fits the model of Plaut and Shallice (1993a), which high-lights lesions in the visual–semantic mapping system as a sufficient sourceof optic aphasia. However, a number of specific questions remain concerningthe aspects of AG’s behavior that the Plaut and Shallice model was not de-signed to simulate (the specific imagery disorder, action-object dissociationsin naming but not in verbal fluency). These specific problems may be func-tionally as well as clinically associated with optic aphasia.

APPENDIX A

Test 1.1. Naming and Gesturing to Three Sensory Modalities

Set A Set B

Button (boton) Zip (cierre)Candle (vela) Match (cerilla)Carrot (zanahoria) Apple (manzana)Cigarette (cigarrillo) Pipe (pipa)Comb (peine) Hairbrush (cepillo)Comforter (chupete) Safety pin (imperdible)Cup (taza) Knife (cuchillo)Envelope (sobre) Stamp (sello)Eraser (borrador) Pencil (lapiz)Fork (tenedor) Spoon (cuchara)Glove (guante) Belt (cinturon)Hammer (martillo) Pliers (alicates)Key (llave) Padlock (candado)Paper clip (clip) Washing tongs (pinzas)Piece of chalk (tiza) Notebook (libreta)Plug (enchufe) Light bulb (bombilla)Ring (anillo) Necklace (collar)Ruler (regla) Paintbrush (pincel)Screwdriver (destornillador) Scissors (tijeras)Sharpener (sacapuntas) Spectacles (gafas)String (cuerda) Sellotape (papel celo)Toothbrush (cepillo de dientes) Soap (jabon)Watch (reloj) Bracelet (bracelete)Wool (lana) Cotton reel (hilo)


Examples of oral definitions:What is the name of the piece of clothing used to enclose the hand? gloveWhat is the name of the object with a wooden handle and a very heavy

head of metal. The head has one flat end and one end that could beclawed? hammer

What is the name of the object that rests on the nose and helps eyesight? spectaclesWhat is the name of an orange, elongated vegetable which is hard and a

little rough. It has one round end which is thicker than the other? carrotWhat is the name of a metal object that opens and closes a lock? keyWhat is the name of a kind of pincers made of metal with long, flat jaws? pliers

Examples of AG’s errors: NAMING

OBJECTS: VISUAL MODALITYKey: ‘‘That . . . a I can’t remember, it’s for electricity, no, for water.’’

(Es . . . un no recuerdo, es de luz, no, de agua. [‘‘Llave’’ in Spanish isused to indicate a light switch and a tab, besides meaning key].)

Hammer: ‘‘To bang.’’ (Es para golpear.)Scissors: ‘‘Cutting.’’ (Cortando.)Comb: ‘‘For hair, to comb yourself.’’ (Para el pelo, para peinarse.)

OBJECTS: TACTILE MODALITYPiece of chalk: ‘‘It’s a sort of pencil.’’ (Es como si fuera un lapiz.)Paper clip: ‘‘I don’t know.’’Sellotape: ‘‘A sort of wheel.’’ (Parece una ruedita.)

APPENDIX B

Test 3.4. Examples of Items Presented and AG’s Responses

Free description of pictured objects and named objectsORAL PRESENTATION

What is a monkey? ‘‘It’s an animal of the jungle, it’s like a human being, it’s cov-ered with lots of hair, it walks on two or four legs, it climbs trees, they like play-ing.’’ (Es un animal de la selva, es como si fuera un humano, esta cubierto de mu-cho pelo, anda con dos o con las cuatro patas, sube a los arboles, les gusta jugar.)

What is a piano? ‘‘It’s an instrument for playing, for playing music, with long nar-row things, keys, black and white. There are very large pianos and other modernsmaller ones, all of them, I think, have a pedal also. I think they are all made ofwood, what happens is that they are very shiny, well it depends upon the piano, ofcourse. There are various colors, wood . . .’’ (Es un instrumento de tocar, de tocarmusica, con cosas alargadas y estrechas, clavijas blancas y negras. Hay pianosgrandısimos y otros modernos mas pequenos, todos, yo creo, tienen el pedal tam-bien. Yo creo que todos son de madera, lo que pasa es que son muy relucientes,bueno, depende de que piano, claro. Hay de varios colores, madera . . .)

What is a tree? ‘‘They are over there, in front of the house, in the fields, on theother side of the road. They have a lower part and an upper part, the lower part isalways the same, although fatter or thinner and the upper part differs. The branchescan be long, short, big, small, fat. They differ also with respect to the leaves, flow-ers. That is, the shape of one tree is different from that of another. The color of theupper part is green and the lower part is like this (points to the wood of the ta-ble).’’ (Estan ahı enfrente, en el campo, en el otro lado de la carretera. Tienen unaparte de abajo y una parte de arriba, la de abajo es siempre igual aunque masgordo o mas delgado y la parte de arriba se diferencia. Son las ramas que pueden

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ser mas grandes, largas, cortas, pequenas, gordas. Se diferencia en las hojas, enlas flores, eso es una forma de arbol y es diferente de otro. El color es verde de laparte de arriba y de abajo es como esta.)

VISUAL PRESENTATIONMonkey: ‘‘It’s a monkey lying, resting on a bench, a table really or on the ground.’’

(Es un mono acostado descansando en un banco, una mesa realmente o en elsuelo.)

Piano: ‘‘It’s a board for ironing, how can I say? (gesture of playing piano with bothhands and pressing on a pedal with his foot) I am connecting the electricity to playand it also has something for one’s foot. It’s a press, really. For playing.’’ (Es unaprensa pra planchar, como le diria yo? Le doy a la electricidad para tocar y tienetambien para apoyar el pie, es una prensa en realidad. Para tocar.)

Tree: ‘‘It’s like flowers, flower pots, plants.’’ (Es como flores, macetas, plantas.)

APPENDIX C

Examples of Items Presented in Task 4.7. Visual and Functional Attributes

NAMING TASK: VISUAL PRESENTATIONKangaroo, tortoise, parrot, monkey, owl, butterfly, frog, ladybird, bull, zebra, cow, bee,

and cat

NAMING TASK: ORAL DESCRIPTION OF VISUAL ATTRIBUTESWhich animal has sharp ears, a long, strong tail and back legs, with small front legs and

a bag in its belly? (Kangaroo)Which is animal is hairy and looks a little like a human? (Monkey)What do you call the hook-beaked, large, flat-faced, round-headed, very large and dark-

eyed, soft plumaged bird? (Owl)What is the name of a greenish, tailless, smooth-skinned animal that is always wet. It

has large pop eyes well separated one from the other. (Frog)

NAMING TASK: ORAL DESCRIPTION OF FUNCTIONAL ATTRIBUTESWhat animal moves forward by jumping helped by its tail and back legs?What animal swings from the branches of the trees and likes to play with its mates?What bird stays awake all night long and flies silently?Which is the animal whose female lays its eggs in water and whose male gets a swollen

throat when making a particular noise?

REFERENCES

Beauvois, M. F. 1982. Optic aphasia: A process of interaction between vision and language.Philosophical Transactions of the Royal Society of London. B. 298, 35–47.

Beauvois, M. F., & Saillant, B. 1985. Optic aphasia for colours and colour agnosia: A distinc-tion between a visual and visuo-verbal impairment in the processing of colours. CognitiveNeuropsychology, 2, 1–48.

Biederman, I. 1987. Recognition by components: A theory of human image understanding.Psychological Review, 94, 115–145.

Bisiach, E. 1966. Perceptual factors in the pathogenesis of anomia. Cortex, 2, 90–95.Caramazza, A., & Hillis, A. 1991. Lexical organisation of nouns and verbs in the brain. Nature,

349, 788–790.


Caramazza, A., Hillis, A., Rapp, B. C., & Romani, C. 1990. The multiple semantic hypothesis:Multiple confusions? Cognitive Neuropsychology, 7, 161–189.

Cartwright, S., & Avery, H. 1979. First thousand words in Spanish/ English/ French/ Italian/German. London: USBORN.

Chertkow, H., Bub, D., & Caplan, D. 1992. Constraining theories of semantic memory pro-cessing: Evidence from dementia. Cognitive Neuropsychology, 9, 327–364.

Coslett, H., & Saffran, E. 1989. Preserved object recognition and reading comprehension inoptic aphasia. Brain, 112, 1091–1110.

Davidoff, J., & Ostergaard, A. L. 1984. Colour anomia resulting from weakened short-term-memory. Brain, 107, 415–431.

De Vreese, L. P. 1991. Two systems for colour naming deficits: verbal disconnection vs. thecolour imagery disorder. Neuropsychologia, 29, 1–18.

Ellis, A. W., & Young, A. W. 1988. Human cognitive neuropsychology. Hove, U.K.: Erlbaum.Farah, M. 1984. The neurological basis of mental imagery: A componential analysis. Cogni-

tion, 18, 245–272.Farah, M. 1988. Is visual imagery really visual? Overlooked evidence from neuropsychology.

Psychological Review, 95, 307–317.Farah, M. 1990. Visual agnosia: Disorders of visual recognition and what they tell us about

normal vision. Cambridge: MIT Press.Farah, M., Hammond, K., Levine, D., & Calvanio, R. 1988. Visual and spatial mental imagery:

Dissociable systems of representation. Cognitive Psychology, 20, 439–462.Freund, C. S. 1989. Ueber optische Aphasie und Seelenblindheit. Archiv fuer Nervenkrank-

heiten, 20, 276–297.Funnell, E., & Sheridan, J. 1992. Categories of knowledge? Unfamiliar aspects of living and

non-living things. Cognitive Neuropsychology, 9, 135–154.Gainotti, G., Miceli, G., Caltagirone, C., Silveri, M. C., & Masullo, C. 1981. The relationship

between the type of naming error and semantic–lexical discrimination in aphasic patients.Cortex, 17, 401–409.

Gainotti, G., Silveri, M. C., Villa, G., & Miceli, G. 1986. Anomia with and without comprehen-sion disorders. Brain and Language, 29, 18–33.

Gazzaniga, M. 1970. The bisected brain. New York: Appleton–Century–Crofts.Garcia-Albea, J., & Sanchez-Bernados, M. 1986. El Test de Boston en la evaluacion de la

afasia. Madrid: Panamericana.Geschwind, N. 1965. Disconnection syndromes in animals and man. Brain, 88, 237–294; 585–

644.Goodglass, H., & Kaplan, E. 1983. The assessment of aphasia and related disorders, 2nd ed.

Philadelphia: Lea & Febiger.Hillis, A., Rapp, B., Romani, C., & Caramazza, A. 1990. Selective impairment of semantics

in lexical processing. Cognitive Neuropsychology, 7, 191–243.Hinton, G., & Shallice, T. 1991. Lesioning an attractor network: investigations of acquired

dyslexia. Psychological Review, 98, 74–95.Humphreys, G., & Riddoch, M. J. 1987. To see but not to see: A case study of visual agnosia.

London, Erlbaum.Howard, D., & Orchard-Lisle, V. 1984. On the origin of semantic errors in naming: Evidence

from a global aphasic. Cognitive Neuropsychology, 1, 163–190.Howard, D., & Patterson, K. E. 1988. The Pyramids and Palm Trees Test (unpublished).Jackendoff, R. 1987. On beyond zebra: The relation of linguistic and visual information. Cog-

nition, 26, 89–114.Kaplan, E., Goodglass, H., and Weintraub, S. 1983. The Boston Naming Test. Philadelphia:

Lea & Febiger.Kay, J., & Ellis, A. W. 1987. A cognitive neuropsychological case study of anomia: Implica-

tions for psychological models of word retrieval. Brain, 110, 613–629.Kosslyn, S. 1975. Information representation in visual images. Cognitive Psychology, 7, 341–

370.

OPTIC APHASIA 221

Lhermitte, F., & Beauvois, M-F. 1973. A visual-speech disconnexion syndrome: Report of acase with optic aphasia, agnosic alexia and colour agnosia. Brain, 96, 695–714.

Manning, L., & Campbell, R. 1992. Note: Optic aphasia with spared action naming: A descrip-tion and possible loci of impairment. Neuropsychologia, 30, 587–592.

Meadows, J. C. 1974. Disturbed perception of colours associated with localized cerebral le-sions. Brain, 97, 615–632.

Oxbury, J., Oxbury, S., & Humphreys, N. 1969. Varieties of colour anomia. Brain, 92, 847–860.

Plaut, D. C., & Shallice, T. 1993a. Perseverative and semantic influences on visual objectnaming errors in optic aphasia: A connectionist account. Journal of Cognitive Neurosci-ence, 5, 89–117.

Plaut, D. C., & Shallice, T. 1993b. Deep dyslexia: A case study in cognitive neuropsychology.Cognitive Neuropsychology.

Riddoch, M. J. 1990. Loss of visual imagery: A generation deficit. Cognitive Neuropsychology,7, 249–273.

Riddoch, M. J., & Humphreys, G. 1987. Visual object processing in optic aphasia: A case ofsemantic access agnosia. Cognitive Neuropsychology, 4, 131–185.

Rumelhart, D., & McClelland, J. L. 1981. Interactive processing through spreading activation.In A. M. Lesgold & C. Perfetti (Ed) Interactive Processes in Reading, Hillsdale, N.J.,Lawrence Erlbaum.

Shallice, T. 1987. Impairments of semantic processing: Multiple dissociation. In M. Coltheart,G. Sartori & R. Job. (Eds.), The cognitive neuropsychology of language. London: Erl-baum.

Shallice, T. 1988. Specialisation within the semantic system, Cognitive Neuropsychology, 5,133–142.

Warrington, E., & James, M. 1986. Visual object recognition in patients with right hemispherelesions: Axes or features? Perception, 15, 355–366.

Warrington, E., & James. 1991. The VSOR Test of Visual Function. Berkshire: NFER.Zingeser, L., & Berndt, R. 1988. Grammatical class and context effects in a case of pure

anomia: Implications for models of lexical processing. Cognitive Neuropsychology, 5,473–516.

Optic Aphasia: A Case with Spared Action Naming and Associated Disorders

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