RECENT RESEARCH ON EMERGENT VERBAL BEHAVIOR:CLINICAL APPLICATIONS AND FUTURE DIRECTIONS

LAURA L. GROW AND TIFFANY KODAK

MUNROE-MEYER INSTITUTE

UNIVERSITY OF NEBRASKA MEDICAL CENTER

This paper describes recent studies that have evaluated the functional independence of verbaloperants. Procedures that facilitate the emergence of untrained verbal operants and importantareas of future research to increase efficiency of language programs for children diagnosed withdevelopmental disabilities are discussed.

Key words: emergent relations, functional independence, language training, verbalbehavior

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Previous research on the acquisition of verbalbehavior in children with developmental dis-abilities has focused on teaching four primaryverbal operants (Sundberg & Michael, 2001;Sundberg & Partington, 1998). The mand isevoked by an establishing operation and ismaintained by access to a response-specificreinforcer. For example, a child says waterafter engaging in physical activities (i.e., themotivative operation manipulation) that resultin access to water (i.e., the reinforcer). The tactis under the discriminative control of anonverbal stimulus and produces generalizedreinforcers. For example, a child says dogwhile observing a dog at a park, which results inpraise from a parent. A response that has point-to-point correspondence with a preceding vocalstimulus is an echoic (e.g., saying fish aftersomeone says fish). An intraverbal lackspoint-to-point correspondence with an ante-cedent verbal discriminative stimulus (SD).Answering a car following the verbal stimulusWhat do you ride in? is an example of anintraverbal response.

In Skinners (1957) analysis of verbalbehavior, he stated that each verbal operant ismaintained by unique antecedent and conse-quence events and, therefore, is functionallyindependent. That is, training a specificresponse under one source of control (e.g.,mand) does not necessarily result in theemergence of other verbal operants (e.g., tact)without direct instruction. Skinners workserved as a catalyst for a growing body ofliterature that has evaluated the functionalindependence of verbal operants and theemergence of untrained verbal operants. In thisreview, we will describe recent studies that haveevaluated the functional independence of verbaloperants and procedures designed to promoteemergent verbal behavior. We will suggestdirections for future research to identifyprocedures that reliably produce emergentverbal behavior in children with developmentaldisabilities.

Several studies have demonstrated the func-tional independence of verbal operants, thusproviding support for Skinners (1957) asser-tion that learners may need specific training fora vocal response to occur across a variety ofcontexts (Hall & Sundberg, 1987; Lamarre &Holland, 1985). More recently, research hasfocused on identification of the conditionsunder which topographically similar responsesoccur across verbal operants. Kelley, Shillings-burg, Castro, Addison, and LaRue (2007)

Address correspondence to Laura Grow, who is nowat St. Cloud State University, 720 4th Avenue South,St. Cloud, Minnesota 56301-4498 (e-mail: llgrow@stcloudstate.edu).

doi: 10.1901/jaba.2010.43-775

We thank Sarah Lechago for her helpful comments onan earlier draft of this review.

JOURNAL OF APPLIED BEHAVIOR ANALYSIS 2010, 43, 775778 NUMBER 4 (WINTER 2010)

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examined the functional independence ofmands and tacts for three children withdevelopmental disabilities. The experimentertrained one set of stimuli as a tact relation andthe other set as a mand relation. The experi-menter also probed the untrained relation (i.e.,either a mand or tact) after the participantsacquired the trained relation. Results indicatedthat the untrained relation emerged in 9 of 15opportunities. Participants in the Kelley et al.study and in a study by Petursdottir, Carr,and Michael (2005) did not reliably emitmands after tact training; however, other studieshave demonstrated this type of emergence(Egan & Barnes-Holmes, 2009; Wallace, Iwata,& Hanley, 2006).

One interesting finding is that participantswere slightly more likely to emit tacts aftermand training and were less likely to engage inmands after tact training, which is consistentwith results from other studies (e.g., Petursdot-tir et al., 2005). In the Petursdottir et al. study,participants engaged in self-echoics in thepresence of the stimulus during mand training,which may have facilitated the emergence oftact relations (Esch, Esch, McCart, & Peturs-dottir, 2010). That is, participants repeated thetarget response when they had access to the itemwithout a requirement or consequence fordoing so. Future research might evaluate therole of self-echoics in the emergence ofuntrained verbal operants.

A limitation of the Petursdottir et al. (2005)and Kelley et al. (2007) studies is that theantecedent arrangement was impure. That is,the mand included components of the tactrelation (i.e., the sight of the target item).Participants may have been more likely to emitthe vocal response during mand probes becauseof the presence of the item rather than therelevant establishing operation. An importantimplication of this finding is that incorporationof stimuli that occasion trained verbal operantsmay facilitate the emergence of untrained verbaloperants (Stokes & Baer, 1977).

The research described above evaluated thefunctional independence of mands and tacts;however, other research has examined emergentintraverbal behavior (Perez-Gonzalez, Garcia-Asenjo, Williams, & Carnerero, 2007; Perez-Gonzalez, Herszukowicz, & Williams, 2008;Petursdottir, Carr, Lechago, & Almason, 2009;Petursdottir, Olafsdottir, & Aradottir, 2008).The study by Petursdottir et al. (2008)evaluated emergent unidirectional and bidirec-tional intraverbal relations following either tactor listener training. The experimenter conduct-ed listener training by placing three pictures offruit in an array and providing the instructionin Icelandic (e.g., Which fruit is called[Spanish name]?). The emergence of untrainedintraverbal relations was most likely when theantecedent stimuli or target response in theintraverbal trial was similar to that of thetrained listener or tact relation. For example,the experimenter presented an SD duringlistener training and the second intraverbal SD

that contained similar wording (i.e., Which[fruit or animal] is called [Spanish name]?during listener training and What does[Spanish name] mean? for the Spanish-Icelan-dic intraverbal). Both participants respondedaccurately during the intraverbal probe thatmore closely matched the SD presented duringlistener training. Overall, the results of thisstudy suggested that relations may be morelikely to emerge under similar stimulus condi-tions or when similar responses are required. Inclinical practice, the careful arrangement ofresponses and discriminative stimuli duringlistener and tact training may facilitate subse-quent acquisition of related intraverbal respons-es; future research on this topic is warranted.

The aforementioned research on emergentverbal behavior suggests that untrained verbaloperants occur under some circumstances andnot others. An important direction for futureresearch is to identify procedures that morereliably promote generalization across verbaloperants, which may facilitate the acquisition of

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verbal behavior for children with languagedelays. Multiple-exemplar instruction (MEI) isone procedure that has produced the emergenceof untrained verbal operants (Greer, Yuan, &Gautreaux, 2005; Nuzzolo-Gomez & Greer,2004; Perez-Gonzalez et al., 2007). MEIinvolves training a topographically similarresponse across multiple verbal operants inone teaching session. Greer, Stolfi, Chavez-Brown, and Rivera-Valdes (2005) conductedMEI training with three typically developingpreschool children. They taught visualvisualmatching relations with an embedded instruc-tion (i.e., the experimenter said the name of thestimulus while the participants matched thestimuli). Next, they probed listener, tact, andimpure tact relations (i.e., combining a nonvo-cal and vocal SD). Following visualvisualmatching training, participants emitted un-trained listener responses but did not emit tactor impure tact responses. They then taught allfour relations for a second set of stimuli usingMEI. That is, trials of matching with embeddedinstruction, listener, tact, and impure tactrelations were targeted in one teaching sessionfor each stimulus in the set. One stimulus setoriginally trained only as a matching relationwas probed for the listener, tact, and impuretact relations after MEI. Emergence of un-trained listener, tact, and modified tact relationsoccurred for all participants as a result of anMEI history, although this finding was incon-sistent across sets of stimuli. These results areconsistent with other recent studies that havedemonstrated emergent relations after MEI(Greer et al., 2005; Nuzzolo-Gomez & Greer,2004).

Multiple-exemplar instruction is a promisingprocedure that warrants additional investigationto better understand its clinical utility. Al-though studies have demonstrated emergence ofuntrained verbal relations after MEI, thisfinding is sometimes variable or occurs onlyafter extensive training. To date, few studieshave examined the emergence of untrained

verbal operants after an MEI history, particu-larly for children with autism spectrum disor-ders (Fiorile & Greer, 2007). Moreover, theeffectiveness of MEI may rely on alreadyestablished repertoires that facilitate the emer-gence of verbal operants. Future research mightidentify repertoires that are associated withrapid generalization across verbal operants (e.g.,self-echoics) after MEI training. This type ofresearch could inform the skills that are assessedand targeted in early intervention programs tomaximize learning when MEI is implemented.

Many of the procedures used to studyemergent verbal behavior (e.g., stimulus equiv-alence, MEI) probe untrained verbal operantsduring extinction to isolate the effects oftraining on the subsequent emergence of verbalbehavior (e.g., Groskreutz, Karsina, Miguel, &Groskreutz, 2010). In clinical practice, the useof extinction to probe emergent verbal behaviormay be contraindicated because newly acquiredbehavior is less likely in the absence of directreinforcement, particularly for children withdevelopmental disabilities. Given the variablefindings in much of the emergent verbalbehavior literature, additional clinical researchis needed to evaluate stimulus arrangements orprocedures that are more likely to evokeuntrained verbal operants (LeBlanc, Miguel,Cummings, Goldsmith, & Carr, 2003). Infuture clinical studies, researchers could conductbaseline and probe sessions using continuousschedules of reinforcement to eliminate theprovision of reinforcers as a variable responsiblefor the emergence of untrained relations.

Another possible avenue of future researchinvolves an examination of the influence ofstimulus control on emergent verbal behavior.When evaluating the results of many of thestudies in this review, one theme is apparent.Individuals emitted untrained verbal relationsmore often when the experimenter probedresponses under similar stimulus conditions orwhen they required similar responses. Given thepaucity of research in the area of emergent

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relations, researchers might consider conductinga more thorough analysis of the role of stimuluscontrol on emergent verbal behavior to identifymore effective procedures for evoking untrainedrelations. Early intervention programs areparticularly well suited for conducting this typeof research, given that language training is oftena primary focus for many children withdevelopmental disabilities.

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Received May 8, 2010Final acceptance July 26, 2010Action Editor, Dorothea Lerman

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