The Analysis of Verbal Behavior

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Approaches to understanding and teachingcommunication skills to children with autismand developmental disabilities have been de-veloped by explicitly applying Skinner’s (1957)analysis of verbal behavior (Sundberg &Partington, 1998). These current approachesto early intensive behavioral intervention forchildren with autism, sometimes referred to asApplied Verbal Behavior, Verbal Behavior, orsimply ABA, target the acquisition of distinctand functional verbal operants rather than fo-cusing upon topographies according to thetraditional receptive/expressive dichotomy(Lerman et al., 2005). It is this analysis of ver-bal behavior that will allow behavior analyststo approach topics common in linguistics andpsychology (Sundberg, 1998).

A few controlled studies have been con-ducted on transferring stimulus control be-tween verbal operants in children with autism(Barbera & Kubina, 2005; Drash, High, & Tu-dor, 1999; Partington, Sundberg, Newhouse,& Spengler, 1994; Sundberg, Endicott, &Eigenheer, 2000).

Sundberg and Partington (1998) have dis-cussed transfer of stimulus control or “quicktransfer” procedures extensively. For instance,they described a procedure which transferscontrol of the spoken response dog from a ver-

bal stimulus to respond (“What is that?”), anonverbal stimulus (picture of dog) and anechoic stimulus (spoken word dog) to “Whatis that?” plus the picture of the dog or thepicture of the dog alone. Here, they suggestpresenting the picture of the dog to the childalong with “What is that?” together with theechoic prompt, “Dog, say ‘dog.’” The conse-quence for the child saying dog is praise andpossibly physical contact, if that is reinforcing(the physical contact would eventually befaded out, as it is not a typical consequencefor tacting). After implementing this part of theprocedure, the next step is to fade out the echoicprompt. This may be accomplished by increas-ing the delay between the question and thedelivery of the echoic prompt, or by fadingfrom full to partial echoic prompts. The echoicprompt is continuously reduced until the spo-ken response dog occurs in the absence of theprompt. The stimulus to respond, “What isthat?” should also be faded out if the goal is toobtain spontaneous tacting. After this promptis faded out, the response dog is solely underthe stimulus control of the nonverbal stimulusand the presence of an audience.

As this study addresses stimulus controland transfer of stimulus control procedures,these terms will be defined briefly. Stimuluscontrol refers to a change in operant behaviorthat occurs when a particular type of stimulus(SD or SΔ) is presented. With an SD, the behav-ior occurs in the presence of that stimulus and

Assessing Transfer of Stimulus Control Procedures AcrossLearners With Autism

Christopher Bloh, Kutztown University

The purpose of this study was to evaluate the effectiveness of two transfer of stimulus control proceduresto teach tacting to individuals with autism. Five participants with differing verbal skills were assessed bya subset of the ABLLS prior to intervention, then were taught 36 previously unknown tacts using thereceptive-echoic-tact (r-e-t) and echoic-tact (e-t) transfer procedures. Each transfer method was usedseparately to establish different tacts, in a multiple baseline design across tacts for three sets of stimuli. Theresults showed that 4 out of 5 participants (who demonstrated mands, tacts, echoics, and sometimesintraverbals prior to the study) acquired all targeted tacts when either r-e-t or e-t training was presented.One participant (who emitted no verbal operants at the onset of the study) did not acquire any tacts. Whilesome participants appeared to learn more quickly with one transfer method, neither method emerged asmore efficient with learners with fewer or more extensive verbal skills. The results indicate that both transfermethods promoted the acquisition of tacts for learners with autism with at least minimal verbal skills.

Key words: transfer of stimulus control, receptive-echoic-tact transfer procedure, echoic-tact transferprocedure, autism

2008, 24, 87–101

Address Correspondence to: Christopher Bloh,Ph.D., BCBA, Kutztown University, Beekey 102P.O. Box 730 Kutztown, PA 19530

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does not occur in its absence. With an SΔ, thebehavior does not occur in the presence of thatstimulus. Stimulus control develops when agiven response is repeatedly reinforced in thepresence of a particular stimulus (SD) and notin its absence, or not in the presence of a differ-ent stimulus (SΔ). Transfer of stimulus controloccurs when behavior initially evoked (con-trolled) by one SD comes under the control of adifferent SD. For instance, suppose that a childsays cup in the presence of the echoic prompt,“Say ‘cup.’” If a picture of a cup plus “What isthat?” is then presented, the echoic prompt isfaded, and the child comes to say cup in thepresence of the picture of the cup (nonverbalstimulus), transfer of stimulus control fromechoic to tact variables has been demonstrated.The response form cup, which was previouslycontrolled (evoked) by the verbal stimulus cup,is now controlled by the picture of the cup (non-verbal stimulus).

Sundberg and Partington (1998) have sug-gested several initial behaviors and verbal op-erants which are important for early learners toacquire. These include approaching a trainer orteacher, emitting a single response to obtain ahighly reinforcing item, emitting several re-sponses to gain access to an item or activityover a series of interactions, manding for highlypreferred items, imitating actions and verbalstimuli, and complying with instructions. Theyemphasize the importance of teaching mandsas the first verbal operant, as manding allowsthe learner to gain access to preferred itemsand activities, and may preclude the develop-ment of severe challenging behaviors. Once achild has developed these initial skills, labelingor tact training can begin.

The purpose of the present study was to in-crease the verbal skills of children with autism;specifically, to establish a tact repertoire. Theability to verbally label everyday items and ac-tions is a cornerstone of language development(Sundberg & Partington, 1998). Tacts play acritical role from the simple tacts of labelingitems to complex ones of inferring meaning(Lowenkron, 2004). Children with tacting defi-cits may experience significant communicativeimpairments (Barbera & Kubina, 2005). Devel-oping effective procedures for establishingstimulus control, where a child can tact a stimu-lus within his environment, has wide utility forthose children having a difficulty interactingwith other individuals.

Barbera and Kubina (2005) evaluated a com-bination of transfer procedures commonly usedto teach tacts to children with autism. Theseresearchers used a combination of receptive-to-echoic-to-tact (r-e-t) and echoic-to-tact (e-t)transfer procedures to teach tacts to one par-ticipant with extensive verbal skills. The au-thors concluded that the concurrent use of thetwo transfer procedures resulted in the suc-cessful acquisition of the targeted verbal oper-ants. Pictures of the target stimuli were placedon a table and the participant was told to “touch___.” The participant received a physical orgestural prompt, if needed, to touch the targetstimulus. If he echoed the name of the targetstimulus as he touched the picture, the echoic-to-tact transfer was immediately attempted. Thepicture of the target stimulus was held up andthe clinician said, “Right, what is it?” If noresponse, the clinician said the name of the tar-get stimulus and if the participant echoed thename, the clinician again said, “Right, what isit?” If the transfer to tact was not successful,the clinician went back to the receptive promptfor a different target stimulus by saying “touch___.” If the participant echoed the name of thesecond target stimulus, the tact transfer wasattempted for it. If the participant displayed noechoic response, the third target stimulus onthe table was used to attempt the receptive-to-echoic-to-tact transfer. These procedures werecombined in a very fluid process, movingquickly from receptive-to-echoic-to-tact or froma nonresponse or error to a receptive prompt.The dual use of these interventions was effec-tive in transferring and establishing stimuluscontrol for the participant. The authors sug-gested that the receptive component of the r-e-t procedure may facilitate training for childrenwho cannot always be prompted to respond.

The present study extended Barbera andKubina (2005) by evaluating effectiveness ofthe r-e-t and e-t transfer procedures in a differ-ent format with a larger number of participantswith varied verbal repertoires. The present for-mat differed from that of Barbera and Kubina inthat r-e-t and e-t procedures were used indi-vidually in separate sessions to teach differentsets of tacts, rather than in combination to teachall tacts. Since r-e-t and e-t procedures wereidentical except for the receptive component,one purpose of this study was to evaluate thepossible contribution of the receptive compo-nent of the procedures.

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METHOD

Participants

Four children and one adult participated inthis study.

Mike is a 12-year-old boy diagnosed withautism and profound mental retardation. Ac-cording to his parents, he was verbal until aboutage two. At the time of this study, his parentsalso reported that he occasionally vocalizedthree to five words in context, although thisinvestigator did not observe that he emittedany verbal operants. He vocalized, but did notemit any recognizable words. Mike also didnot point to or touch pictures or objects in re-sponse to a prompt to do so (i.e., he lackedreceptive skills).

Matt is a 6-year-old boy with autism and mod-erate mental retardation. His father reportedthat Matt used some words until approximately12–18 months of age, when he stopped verbal-izing. At the time of this study, he mandedusing 1–2 words, tacted, and emitted echoicbehavior.

Bob is an 11-year-old boy with autism andmoderate mental retardation. His father indi-cated that Bob verbalized until approximately18 months of age, then stopped. According tohis mother, Bob’s verbal behavior increased inthe last couple of years. At the time of thisstudy, Bob manded using 1–2 words, tacted,and emitted echoic behavior.

Jordan is a 12-year-old boy with autism andmild mental retardation. Jordan’s parents re-ported no dramatic regression in his languageskills. At the time of the study, Jordan dis-played strong echolalia and responded to ques-tions when they were repeated 4–5 times. Healso manded and tacted.

Jack is a 21-year-old man with autism andmild mental retardation. His mother reportedthat he never displayed appropriate languagepragmatics as a child. Although he slowly ac-quired a vocal repertoire, he never emitted re-sponses beyond several words. At the time ofthis study, Jack’s verbal repertoire consisted ofmands, tacts, echoics, and intraverbals. He didnot converse socially with others.

Prior to intervention, participants’ verbalskills were assessed by means of a subset ofthe ABLLS (Partington & Sundberg, 1998). TheABLLS is a criterion-referenced assessment andskills tracking system designed for children with

language delays that informs both parents andprofessionals regarding a child’s current skilllevels. It also serves as a curriculum guide andprovides information that can serve as a basisfor targeting educational objectives. For pur-poses of the present study, three domains ofThe ABLLS were used: Receptive Language(52 tasks), Vocal Imitation (9 tasks), and Label-ing (42 tasks). Domains assessing receptiveskills, echoic behavior, and tacts were selectedbecause these verbal operants were targetedfor training in the present study. The 103 itemsselected from The ABLLS rate each task on ascale from 0–2 or 0–4, and the results for eachof the 103 tasks were added to produce asummative rating for each participant. Bymeans of these ratings, the verbal skills of eachparticipant were quantified to obtain ordinal datafor comparison across participants. The par-ticipants’ summative ratings on these domainsof the ABLLS are as follows: Jack, 331; Jordan,267; Bob, 175; Matt, 85; and Mike, 10. Partici-pants’ scores on all three domains of the ABLLSfollowed the same pattern as their cumulative“rankings”; that is, Jack had the highest scoresin all three domains, Jordan had the secondhighest scores, Bob, the third, etc. Thus, par-ticipants’ skill levels were consistent across thethree domains. Based on both the cumulativeassessment and individual domain data, Jackmight be expected to acquire tacts with fewesttrials to criterion.

Setting

All sessions took place in the participants’homes, at the dining room table. The cliniciansat next to the participant, on the side corre-sponding with his dominant hand. The settingswere not controlled for background noise.

PROCEDURES

Dependent Variable Identification

A pool of approximately 200 pictures of ob-jects was pretested in order to select unknownstimuli to be tacted. The stimulus pictures, eachshowing one object, were obtained from age-appropriate school books and magazines anddisplayed on white 3 x 5” index cards. Eachparticipant was presented with the pictures onthe index cards and asked to tact them. If aparticipant failed to tact a picture correctly, that

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picture was included in the study. This proce-dure was repeated until 36 unknown pictureswere identified for each participant. The pic-tures were then randomly distributed into threesets of twelve—Set 1, Set 2, and Set 3. Thestimulus pictures remained constant for eachspecific transfer procedure during the trainingsessions; that is, with each set of pictures, spe-cific stimuli were used in r-e-t training and oth-ers in e-t training. No picture was used withboth transfer procedures. Identical procedureswere conducted individually for all participants,except that with Mike, only one set of stimuluspictures was presented. The sets of stimuluspictures and transfer methods used for eachparticipant are displayed in Tables 1–5.

Research Design and Baseline

In the present study, the effectiveness of r-e-t and e-t transfer procedures was assessed viaa multiple baseline design across behaviors (i.e.,Set 1, Set 2, and Set 3 tacts). In the initial ses-sion for each set of stimulus pictures, partici-pants were prompted to tact the pictures dis-played on the index cards, as in the cold probeprocedure. No training was presented in thesesessions. There were at least four baseline/probe sessions implemented with each set ofstimuli to determine whether the data werestable. After stability was achieved, trainingcommenced on Set 1 stimuli, while baselinemeasures continued to be gathered on sets 2and 3. After about 12 sessions, after the par-ticipant acquired a number of Set 1 tacts, train-ing began for Set 2, while baseline measurescontinued for Set 3. After approximately 18 ses-sions, after the participant acquired several Set2 tacts, training began for Set 3. Thus, the pro-gression to training on Sets 2 and 3 was deter-mined by the data, in a multiple baseline fashion.

Training Procedures (Independent Vari-ables)

Sets 1, 2, and 3 each consisted of 12 stimuluspictures to be tacted. Six were trained with ther-e-t procedure and 6 with the e-t procedure.Again, the transfer methods remained constantfor each targeted tact with no cross-training(i.e., no tact was trained using both r-e-t and e-t procedures). Beginning with r-e-t, three stimu-lus pictures were placed in front of the partici-pant and the participant was prompted to touch

the targeted picture by saying, “Touch …” Thiswas the receptive component of the interven-tion. Most-to-least prompting ensured that theparticipant touched the correct picture. Afterthe participant touched the targeted picture, hewas verbally prompted to echo the name of thepicture by saying, “Say …” . This was the echoiccomponent of the intervention. If he did notrespond correctly, a whole word prompt (fad-ing to partial word then an initial sound) wasemployed to ensure a correct response. Afterechoing, the participant was prompted to tactthe targeted picture by saying, “Right, what isit?” Again, whole-partial-initial sound prompt-ing was employed. In e-t training, the partici-pant was presented with one picture at a time.The participant was then prompted to “Say …”(echoic relation), then “Right, what is it?” (tactrelation). This method was identical to r-e-ttraining except that only one picture was pre-sented and no prompt to touch the picture wasgiven; that is, the e-t procedure did not includethe receptive component.

For all participants, a specific training se-quence was followed for the 36 tacts. For Sets1, 2, and 3 (each consisting of 12 tacts), r-e-ttraining was implemented for items 1, 2, 3, 7, 8,and 9, and e-t was implemented for items 4, 5, 6,10, 11, and 12. Thus, the training method alter-nated every three tacts; that is, after trainingtacts 1, 2, and 3 with r-e-t procedures, e-t meth-ods were used for tacts 4, 5, and 6, etc.

The training segments were equally dividedin time between the r-e-t and e-t transfer proce-dures. After the first three pictures were cor-rectly responded to by the participant throughr-e-t training, the next prescribed three weretrained by the e-t transfer procedure. The clini-cian held a picture of the targeted tact, promptedthe child to repeat the name, and say the nameof it (echo). If the child did not respond cor-rectly, then the previous correction procedurefor the echoic prompt was employed until hecorrectly responded (most to least prompt fad-ing). After an echoic response was emitted bythe participant, the clinician asked him to tact itwhile the picture remained displayed, “Right,what is it?” The same correction procedurepreviously mentioned for tacting was used. Ifthe participant was unable to emit an echoicprompt, his training continued for the set ofthree tacts until the allotted time (as determinedby the specific experimental phase) expired. Ifhe was unsuccessful after the allotted time had

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expired, training continued to the next set ofdesignated tacts.

Experimental Phases. The study was con-ducted in three phases. For each participant,Phase I consisted of r-e-t and e-t training forSet 1 tacts only, and occurred for 6 minutes (3 r-e-t + 3 e-t) per session. For all participantsexcept Mike, Phase II (training and/or mainte-nance for Set 1 and training for Set 2) beganafter the participant had acquired a number oftacts in Set 1, either via r-e-t or e-t training. Thedecision to move to Phase II was made indi-vidually for each participant, based on his suc-cessful performance in Phase I. During PhaseII, Set 1 training and/or maintenance trials oc-

curred for 4 minutes per session (2 r-e-t + 2 e-t)and Set 2 training trials were implemented for 6minutes (3 r-e-t + 3 e-t) within the same session.For all participants except Mike, Phase III (main-tenance for Set 1, training and/or maintenancefor Set 2, and training for Set 3) began after theparticipant had acquired a number of tacts inSet 2, either with r-e-t or e-t training. DuringPhase III, Set 1 maintenance trials were imple-mented for 2 minutes (1 r-e-t + 1 e-t) per ses-sion, Set 2 training and/or maintenance trials for4 minutes (2 r-e-t + 2 e-t) per session, and Set 3training trials for 6 minutes (3 r-e-t + 3 e-t) persession. Times between sessions were re-corded across participants, based on their

Table 1Mike’s Three Sets of Targeted Tacts and the Transfer Method Employed (Only Set 1 was Used)

Transfer Transfer Transfer method Set 1 method Set 2 method Set 3

r-e-t ball r-e-t socks r-e-t leafcat bird monkeyflowers baby phone

e-t doll e-t apple e-t cupboot pants jetbat shoes watch

r-e-t shirt r-e-t pear r-e-t moontie pen fandog hat towel

e-t ring e-t mouse e-t treeboat toothbrush lemoncar TV star

Figure 1. Mike’s responses for Set 1.

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varying availabilities. These times varied from24 hours to 5 days.

Trials were conducted identically with allparticipants, regardless of their enteringskills, as assessed in three domains of theABLLS (Partington & Sundberg, 1998), asdescribed earlier. The participants assessedwith fewer verbal skills were trained in ex-actly the same way as those with more ex-tensive verbal skills.

Results

Interrater Reliability. Prior to the study,a parent was trained in the interventionsused in the study, for each participant. Thistrained parent observed and collected datain at least 30% of all sessions that were con-ducted by the clinician. At the conclusionof each session observed by the parent, theparent and clinician compared data.Interrater reliability was determined by di-viding the number of agreements by the to-tal amount of trials, and multiplying by 100.Interrater reliability was 100% across all par-ticipants.

Data Analysis. Figures 1–5 show tact per-formance for each participant. With all par-ticipants except Mike, each figure contains 3successive graphs showing Set 1, Set 2, andSet 3 tact performance before and after the r-

e-t or e-t procedures were presented. WithMike, the figure includes one graph show-ing his acquisition of Set 1 tacts before andafter r-e-t and e-t training. This data displayformat is designed to reveal any education-ally significant effects on the dependent vari-ables that can be attributed to the indepen-dent variable. In combination with the ABLLSassessments (Partington & Sundberg, 1998),it might be revealed that one variation of theindependent variable, r-e-t or e-t, is more (orless) effective with individuals with more (orless) complex verbal repertoires. On the otherhand, it is possible that both variations ofthe independent variable may be equally ef-fective with all participants.

Mike

Figure 1 shows tact performance for Mike.As indicated in the graph, he failed to acquireany of the targeted tacts in Set 1. Based on thisperformance, the decision was made to discon-tinue the intervention and not attempt to trainthe Set 2 and Set 3 tacts that had been initiallytargeted. Mike’s Set 1 performance suggestedthat it was unlikely that he would acquire tactsin Set 1 or Set 2, as the pool of tacts was ran-domly distributed prior to training. The inter-vention lasted 13 sessions, with Mike learning0 tacts over 15 days.

Table 2Matt’s Three Sets of Targeted Tacts and the Transfer Method Employed

Transfer Transfer Transfer method Set 1 method Set 2 method Set 3

r-e-t gibbon r-e-t muskrat r-e-t anthook lightning skeletonkazoo brief case cactus

e-t galaxy e-t armadillo e-t dolphinchimpanzee church baconengine flip flops ceiling fan

r-e-t harp r-e-t palm tree r-e-t beaverdiamond hat jackcopier ring outlet

e-t birdhouse e-t lizard e-t sealgrill tomato bootslobster pants elk

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Matt

Figure 2 shows tact performance for Matt.For Set 1, 5 baseline sessions were completedduring which Matt did not correctly respond(or respond at all) for any of the tacts in the set.The training sessions began after the cold probe

for Session 5. Acquisition then occurred morequickly for the targeted tacts using the e-tmethod than for the r-e-t method, with Mattreaching mastery two sessions earlier duringthe e-t method.

During training with Set 2, Matt respondedincorrectly during all 12 baseline sessions. The

Figure 2. Matt’s responses across sets of tacts.

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training procedure was initiated after 7 teach-ing sessions for Set 1. Matt mastered the e-ttacts 1 session before those trained using r-e-t.The rate of acquisition was nearly identical forboth methods.

For Set 3, the training procedure was initi-ated after Set 1 was taught for 12 sessions andSet 2 for 5. Thus, baseline for Set 3 was con-ducted for 17 sessions. Matt achieved masterycriteria simultaneously for both methods; earlyon, however, his rate of acquisition was slightlyquicker using the e-t method. The entire inter-vention lasted 23 sessions, whereby Mattlearned 36 tacts over 31 days.

Bob

The results showing tact acquisition forBob are displayed in Figure 3. Five baselinesessions were implemented for Set 1. Duringthese baseline sessions, Bob did not emit anycorrect tacts. Training began after the coldprobe was conducted in Session 5. He metmastery criteria for tacts trained via r-e-t onesession before mastery of e-t tacts; however,the rate of acquisition for both methods wasvery similar. Additionally, the transfer methodresulting in quicker acquisition fluctuatedthree times before mastery was achieved withboth methods.

During Set 2, Bob responded incorrectly dur-ing all 12 baseline sessions. The training pro-cedure was initiated after 7 teaching sessionsfor Set 1. The more effective transfer methodwas evident during this set. He achieved mas-tery criteria for the r-e-t tacts 3 sessions prior tothose using e-t. Moreover, the rate of acquisi-tion was quicker for the r-e-t tacts.

For Set 3, baseline procedures were con-ducted for 17 sessions; Set 1 was taught for 8sessions, and Set 2 for 6. Bob achieved mas-tery criteria simultaneously with both transfermethods and his rates of acquisition were iden-tical. Bob acquired 36 tacts over 30 days, andthe intervention lasted 22 sessions.

Jordan

The results showing tact acquisition for Jor-dan are displayed in Figure 4. For Set 1, 5 baselinesessions were implemented prior to training.During baseline, Jordan did not correctly tactany targeted stimulus pictures. During training,he acquired the r-e-t tacts more quickly, result-ing in the mastery criterion being met 2 sessionsearlier with r-e-t than the e-t method.

During training on Set 2, Jordan respondedincorrectly during all 14 baseline sessions. Thetraining procedure was initiated after 9 teachingsessions for Set 1. For Set 2, Jordan achieved

Table 3Bob’s Three Sets of Targeted Tacts and the Transfer Method Employed

Transfer Transfer Transfer method Set 1 method Set 2 method Set 3

r-e-t sword r-e-t pitchfork r-e-t ironhelmet cymbals cerealchinchilla i-pod pickle

e-t ax e-t jack e-t pieoutlet lighter skierunicycle bolt barrels

r-e-t lightning r-e-t keyboard r-e-t tuning forkcompass flip flops chocolateeclipse rug kazoo

e-t barbell e-t copier e-t enginecoyote vineyard suspenderstreadmill ceiling fan trombone

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mastery simultaneously for both the r-e-t ande-t tacts. Moreover, with the exception of onesession, rate acquisition was identical for bothtransfer methods.

For Set 3, baseline was conducted for 19 ses-sions, during which Jordan failed to correctly

respond to the targeted tacts. When trainingwas initiated for Set 3, training had been con-ducted for 14 sessions in Set 1 and 6 sessions inSet 2. He achieved mastery criterion for r-e-ttacts one session before those using e-t meth-ods, although the rate of acquisition between

Figure 3. Bob’s responses across sets of tacts.

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the methods did not considerably differ. Theentire study took place over 25 sessions, in whichJordan learned 36 tacts over 33 days.

Jack

The results of tact acquisition for Jack are dis-played in Figure 5. For Set 1, four baselinesessions were implemented prior to training.During baseline, Jack did not tact any targetedstimuli correctly. He achieved mastery criterionwith the e-t method 1 session before those em-ploying r-e-t; however, the transfer method re-sulting in quicker acquisition fluctuated fourtimes before mastery was achieved for e-t.

During Set 2, Jack responded incorrectly dur-ing all 11 baseline sessions. Training had beenimplemented for 7 sessions in Set 1 at the com-mencement of training for Set 2. For Set 2, Jackachieved mastery criteria simultaneously forboth the r-e-t and e-t tacts, though his acquisi-tion rate was slightly quicker with the e-t tacts.

For Set 3, baseline was conducted for 18sessions, during which Jack failed to correctlyrespond to the targeted tacts. When trainingwas initiated for Set 3, training had been con-ducted for 14 sessions in Set 1 and 7 sessionsin Set 2. Jack achieved mastery criteria simul-taneously for both methods; however, his rate

of acquisition was slightly quicker using thee-t method. The intervention lasted 24 ses-sions, whereby Jack learned 36 tacts over 41days.

DISCUSSION

The data show that the r-e-t and e-t proce-dures were effective in establishing tacts infour out of five participants when they werepresented separately in sessions separatedby at least 24 hours rather than in the com-bined manner utilized by Barbera and Kubina(2005). Further, these procedures were usedeffectively with participants with varied ver-bal repertoires. In the case of Mike, how-ever, tact training was unsuccessful. Thismay be due to differences in Mike’s enteringverbal repertoire compared with the other par-ticipants. Mike did not emit conventionalverbal topographies under any conditionsprior to the study, whereas all of the otherparticipants emitted mands and other ver-bal operants.

Regarding the effects of the different trans-fer procedures, with the exception of Jordanand Mike, all participants appeared to re-spond slightly better when the e-t transfermethod was used. This conclusion is sug-

Table 4Jordan’s Three Sets of Targeted Tacts and the Transfer Method Employed

Transfer Transfer Transfer method Set 1 method Set 2 method Set 3

r-e-t scorpion r-e-t chimpanzee r-e-t wildebeestSaturn suspenders centipedeengine crystal porcupine

e-t lemur e-t cheetah e-t platypussyringe church chandeliercar seat emu baboon

r-e-t dumbbell r-e-t tuning fork r-e-t ferretsquid stained glass aardvarkcompass microchip praying mantis

e-t wolverine e-t wallaby e-t i- podcockroach submarine arroworangutan galaxy bow tie

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gested by the faster learning rate across sets.Jack, Bob, and Matt appeared to have mas-tered e-t tacts more quickly for at least 2 of the3 sets of tacts. This conclusion, although vi-sually apparent in the graphs, should not beoveremphasized, as the difference in acquisi-tion between e-t and r-e-t methods was mar-ginal. The difference for Jordan is not as clear,

for he responded better to r-e-t tacts during theinitial set and responded very similarly usinge-t methods during the later sets. No differenceswere present with Mike, since he did not ac-quire any tacts.

One issue to consider is the possibility ofsequence effects when comparing the effectsof r-e-t and e-t training. This concern is related

Figure 4. Jordan’s responses across sets of tacts.

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to what the participant is actually doing in thee-t condition, and whether this may have beenaffected by prior r-e-t training. The receptiveskills acquired in r-e-t become part of theparticipant’s repertoire, which might enhancethe effectiveness of later e-t training. Recep-tive responding could facilitate the acquisitionof tacts in the following manner. In r-e-t train-ing, the participant is presented with three pic-tures of items (nonverbal stimuli) andprompted to “Touch___.” He or she is thenprompted to touch the nonverbal stimulususing most-to-least prompting, if necessary.Thus, in the presence of the spoken word foran item, the participant acquires a repertoire oflooking at, scanning the three nonverbal stimuli,and touching the stimulus that correspondswith the vocal word. When a single stimulus islater presented in the e-t condition, the partici-pant exposed to r-e-t training may have a ten-dency to look closely at it and point to/touch it(receptive responding), which might set theoccasion for the nonverbal stimulus to gaincontrol over the form of the verbal responsemore quickly. There is no evidence that behav-ior trained in the r-e-t condition occurred in thee-t alone condition (it might be necessary tovideotape the session to determine this), butthe possibility has not been ruled out.

It appeared that the effectiveness of thetransfer procedures was dependent on the ver-bal skills of the participants. The data indicatethat the participants’ initial communicative rep-ertoires, and not the type of procedure, werethe main determinants of their performance.Their verbal abilities at the commencement ofthe study appeared to determine their respond-ing efficiency, rather than either transfermethod implemented during the study. Thedata further suggest that both methods weregeneralizable across participants. It appearsthat from Jack to Matt (excluding Mike whofailed to respond at all), both methods in-creased responding. While it was earlier men-tioned that e-t methods were slightly preferred,both methods were effective across learnersof varying verbal abilities.

Which transfer method appeared to be moreeffective across learners of different languageabilities? Unfortunately, the data are inconclu-sive in suggesting a definitive response. Theparticipants’ responses from the subset of TheABLLS (Partington & Sundberg, 1998) suggestfive unique verbal abilities. There appears to beno relation to these abilities and method prefer-ence. For instance, Eric (summative score of 58)did not show method-specific responding pref-erence that differed significantly from Jack

Table 5Jack’s Three Sets of Targeted Tacts and the Transfer Method Employed

Transfer Transfer Transfer method Set 1 method Set 2 method Set 3

r-e-t protractor r-e-t cuff links r-e-t lemurskis flash drive peacockjavelin emery board aardvark

e-t shoe horn e-t crystal e-t platypuswindmill recliner baboonferret tweezers coyote

r-e-t compass r-e-t shoulder pads r-e-t chinchillacockroach armoire centipedetulip eclipse armadillo

e-t screwdriver e-t cleat e-t sealmetal detector gibbon unicyclecrutch jack orangutan

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(summative score of 331). From the data, thereis no evidence that either method is more effec-tive when teaching tacts to learners with au-tism with differing verbal skills. Individuals withmore (or less) complex verbal skills did not re-spond much differently to e-t than r-e-t train-ing. Thus, the receptive component of r-e-t didnot seem to add value to the training, with these

participants. In future research of this nature,it may be necessary to assess participants’ en-tering receptive skills more closely. It is pos-sible that with participants who already exhibitreceptive skills at the onset of the study, thereceptive component of r-e-t would not greatlystrengthen their tendency to look at or touchthe stimulus pictures.

Figure 5. Jack’s responses across sets of tacts.

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Limitations

There are several possible limitations to thisstudy. One consideration when analyzing theresults should be the mastery criteria for a suc-cessful tact. A tact was deemed to be masteredwhen there were 3 consecutive correct re-sponses during the cold probe sessions. Al-though it seldom occurred, there were instanceswhere a participant correctly responded onceor twice and then did not respond correctly.Mastery criteria being 3 consecutive success-ful responses, the participant had to return tozero after the incorrect response, regardless ofa correct history of responding for that tact. Inother words, the participant received ‘no credit’for responding correctly once or twice. Theo-retically, a participant could have correctly re-sponded 15 times, missed 1 cold probe trial,and would have been required to tact the item3 additional times before mastery was againdocumented. A confounding variable may havebeen present in the aforementioned trial andresulted in an incorrect response. This couldbe a potential threat to internal validity, as thechanges in the dependent variable may havenot resulted from the application of the inde-pendent variable. This scenario did not occur,but was possible. Perhaps a mastered tactcould have been defined as two consecutiveresponses. Further, a mastered tact could havebeen defined as one correct response but exitcriteria for the set (12 total tacts) could havebeen three consecutive correct trials.

While mastery criteria may have been a limi-tation, all participants were exposed to bothr-e-t and e-t methods equally. This safeguardwould suggest that a limitation in mastery cri-teria should have equally affected both trans-fer methods. Thus, it should not have greatlycompromised the results.

Another potential limitation was the vary-ing of session frequencies across partici-pants. As previously noted, each participanthad an equal exposure to both independentvariables. The number of sessions neededfor mastery of all 36 tacts cannot be comparedacross participants. Jack, who was assessedto possess the highest communicative abil-ity, required more training sessions to meetexit criteria (24) than were required by Matt(23). A plausible explanation could be thatJack’s sessions occurred over a span of 41days while Matt’s training sessions occurred

over a span of 23 days. While this issue ap-pears unrelated to the question of which trans-fer method is more efficient, one should exer-cise caution in generalizing the study’s re-sults across participants.

Future Research

Areas remain to be explored in assessing theeffectiveness of transfer of stimulus controlprocedures. A possible route could be to as-sess r-e-t versus e-t methods across a numberof participants of similar verbal abilities. Per-haps more participants resembling Jordan’sverbal profile would respond to one methodmore effectively than another.

If r-e-t and e-t training were compared withparticipants entering the study with minimalreceptive repertoires, if might also be desirableto use a different experimental design to con-trol for the possibility of sequence effects. Asmentioned earlier, sequence effects are possiblebecause the receptive component of r-e-t train-ing might change the participant’s attendingrepertoire and thus affect his or her respondingin the e-t condition. A different experimentaldesign might therefore be used in which theorders of r-e-t and e-t training were counterbal-anced with different participants.

An additional direction for future researchmight be to incorporate mand training in theacquisition of tacts. Arntzen & Almås (2002)reported that a combination of mand-tact train-ing, rather than tact-only training led to a morerapid acquisition of tacts. It has been demon-strated that mand contingencies involve stron-ger controlling variables and may facilitate theacquisition of a tacting repertoire. These au-thors suggest that changes in one verbal rep-ertoire may result in collateral changes in a sec-ond. The mand-tact condition provides theopportunity to train two verbal operants asquickly as one verbal operant in a tact-onlycondition. Mand training could be incorpo-rated with training using the receptiveprompt. After a successful receptive promptto identify the targeted tact, the experimentercould then hide the picture and use the in-structions “Find the ___.” When the par-ticipant couldn’t find the object, he wouldbe prompted to mand for it. Employing thisoperant in the transfer method sequence, itcould be considered a receptive-mand-echoic-tact (r-m-e-t) procedure. The meth-

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ods r-e-t, e-t, and r-m-e-t could then be as-sessed to determine effectiveness of tact ac-quisition.

CONCLUSION

This study adds to the body of literaturethat suggest that both r-e-t and e-t transfermethods are effective in teaching tacts topeople with autism, providing that they ex-hibit some verbal responding prior to inter-vention. The receptive component of the in-tervention was not necessary in establishingtacts, at least with these participants. Thisstudy appears to have value for teachers andclinicians serving students with autism.

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Partington, J.W., Sundberg, M.L., Newhouse,L., & Spengler, S.M. (1994). Overcoming anautistic child’s failure to acquire a tact reper-toire. Journal of Applied Behavior Analy-sis, 27, 733–734.

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