Models of Language Language and Cognition Colombo 2011.

Models of Language

Language and CognitionColombo 2011

Principals of Cognitive Models

• A means of conceptualising the stages involved in a mental activity

• Examines components involved in processing information and the interconnections between them (“box and arrow”) or how information flows between centres via pathways

• The boxes and arrows represent a function which can be independently impaired

• Not yet able to link aphasic symptoms to discrete anatomical structures

Principals of Cognitive Models

• Provide a framework for assessment and treatment

• Different models consider different aspects e.g. single words (Ellis and Young 1988) and sentence processing (Garrett 1984).

• Different models share common features, e.g. all have distinct semantic and phonological levels

• We will be focusing on one lexical model widely applied in SLT

Assumptions

• Using this modelling make several assumptions:– Functional modularity – modules/boxes can operate

independently of other components– Anatomical modularity – modules represent different

parts of the brain. Lesions can affect selected modules only, leaving others unimpaired

– Universality – all people have the same fundamental language system (though we might not agree on the system)

– Subtractivity - brain damage can only remove elements from the system, not add them

• N.B:• Lesions in the brain vary from person to person dependent

on:– The precise location of the damage– Which white matter fibre tracts are damaged

• Therefore identical patterns of deficit in any two people unlikely.

• Helpful to look at which boxes/arrows are damaged/intact to help explain pattern of performance.

• Still attempting to relate to brain structures (Hillis 2001)

PALPA

Psycholinguistic Assessments of Language Processing in Aphasia

Introduction

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Abstract Letter Identification

Mousemouse

“yes, these are letters”

Visual Input Lexicon “yes, this is a word”

SemanticSystem “yes, this word means something”

m so

e u

Mouse = N

Phonological Output Lexicon “this word is pronounced /maUs/”

speech“mouse”

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Blikblik

“yes, these are letters”

Visual Input Lexicon “no, this is not a word”

SemanticSystem

b cl

i k

Phonological Output Lexicon

speech

• This doesn’t fit with the facts…

• So there must be another way to read written words

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Blikblik

Visual Input Lexicon

SemanticSystem


speech

Grapheme to Phoneme Conversion

b=/b/ , l=/l/, i=/I/, k=/k/

“blik”

• The lexical route cannot read nonwords at all

• The nonlexical route cannot read irregular spelling-sound correspondences

• We need (at least) both of these routes to be able to read both real and pseudo words

• What about naming an object or a picture?

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SemanticSystem


speech


Visual Object Recognition System

pictures, seen objects

• What about recognizing or repeating speech that you hear?

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SemanticSystem


speech




speech

Auditory Phonological Analysis

“yes, I hear speech sounds”

Phonological Input Lexicon

“yes, that’s a word”

• What about being able to repeat a word you never heard before – or a pseudoword?

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SemanticSystem


speech




speech



Acoustic to Phonological Conversion

• What about people who do not understand what they hear, or what they read, but can still say it?

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SemanticSystem


speech




speech




• What about written output?

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SemanticSystem


speech




speech




Orthographic Output Lexicon

writing

Sound to letter rules

The final product…..

• Kay, Lesser & Coltheart, 1996• PALPA model• Assessments for each box

and arrow – evaluating effects of different inputs and outputs on a damaged language system

• NOT intended to be used in its entirety

• Remains the only psycholinguistically motivated tool for language assessment

Models of Language Language and Cognition Colombo 2011.

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