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The Behavior Analyst 2000, 23, 239-254 No. 2 (Fall)

Understanding Complex Behavior:The Transformation of Stimulus Functions

Simon DymondAnglia Polytechnic University

Ruth Anne RehfeldtSouthern Illinois University at Carbondale

The transformation of stimulus functions is said to occur when the functions of one stimulus alteror transform the functions of another stimulus in accordance with the derived relation between thetwo, without additional training. This effect has been demonstrated with a number of derived stim-ulus relations, behavioral functions, experimental preparations, and subject populations. The presentpaper reviews much of the existing research on the transformation of stimulus functions and outlinesa number of important methodological and conceptual issues that warrant further attention. Weconclude by advocating the adoption of the generic terminology of relational frame theory to de-scribe both the derived transformation of stimulus functions and relational responding more gen-erally.Key words: transfer and transformation of stimulus functions, derived stimulus relations, stimulus

equivalence, relational frame theory, adults and children

Understanding the emergence of be-havior for which an explicit history ofreinforcement is either extremely re-mote or obviously lacking has oftenrepresented a challenge for behavioralanalyses of complex behavior. Recent-ly, however, behavior analysts haveshown considerable interest in the re-search area of derived stimulus rela-tions, which, many argue, may providethe foundations for a behavioral ac-count of novel behavior. Typicallystudied using a matching-to-sample(MTS) procedure, the basic finding isas follows. Suppose, for instance, re-

Material from this paper was presented at theannual conference of the Experimental Analysisof Behaviour Group, London, March 1999.Many thanks to Dermot Barnes-Holmes, PaulSmeets, and three anonymous reviewers forhelpful comments on a previous version. Thefirst author wishes to acknowledge the supportof the British Academy during the preparationof this article.

Please address correspondence and requestsfor reprints to either Simon Dymond, Depart-ment of Psychology, Anglia Polytechnic Uni-versity, East Road, Cambridge, CB1 1PT, UnitedKingdom (E-mail: [email protected]) orRuth Anne Rehfeldt, Rehabilitation Institute,Southern Illinois University at Carbondale, Car-bondale, Illinois 629014609 (E-mail: [email protected]).

inforcement is delivered for selectionof Comparison B in the presence of theSample A and for selection of Com-parison C in the presence of Sample B.Most verbally able humans will readilyreverse these explicitly reinforced con-ditional discriminations in the absenceof further training. That is, they willselect A given B and B given C in ac-cordance with derived symmetrical, ormutually entailed, stimulus relations.Furthermore, subjects will also select Cgiven A and A given C in accordancewith derived transitive and equiva-lence, or combinatorially entailed,stimulus relations without further train-ing. Following such derived perfor-mances, the stimuli are said to partici-pate in an equivalence class (Sidman,1994) or a relational frame of equiva-lence (Barnes, 1994; S. C. Hayes,1991). Perhaps what is most interestingabout derived stimulus relations suchas equivalence is that the test outcomesare not readily predicted from the tra-ditional concept of conditional dis-crimination; neither A nor C has a di-rect history of differential reinforce-ment with regard to the other, and,therefore, neither stimulus should con-trol selection of the other.

239

240 SIMON DYMOND & RUTH ANNE REHFELDT

Another feature of derived stimulusrelations is the transformation of stim-ulus functions, which has also gener-ated research interest due in part to itsimplications for understanding a widerange of complex derived behavior.The transformation of stimulus func-tions occurs when the function of onestimulus in a derived relation alters thefunctions of another according to thederived relation between the two, with-out additional training (Dougher &Markham, 1994, 1996; S. C. Hayes,1991). As a practical example of thetransformation of functions, consideran individual who derives an equiva-lence relation consisting of the spokenword "stop," a stop sign, and a gesturefrom a crossing guard to stop. Later,she may learn that when her teachersays "stop," it is time to stop and waitfor oncoming traffic. Subsequently, thestop sign and the crossing guard's ges-ture may occasion similar behavior onthe part of the individual. This trans-formation of functions is based on thebehavioral function of "stop" and thederived relation between the spokenword and the gesture or the sign.To date, an increasing number of

stimulus-function transformations havebeen studied in several laboratories us-ing a number of different proceduresand subject populations. Several au-thors have argued that these studiesmay have implications for contempo-rary behavior-analytic accounts of, forinstance, self-awareness (Dymond &Barnes, 1997a), stereotyping (Kohlen-berg, Hayes, & Hayes, 1991), dream-ing (Dixon & Hayes, 1999), sexualarousal (Roche & Barnes, 1997), emo-tional disorders (e.g., Dougher, Au-gustson, Markham, Greenway, & Wul-fert, 1994; Friman, Hayes, & Wilson,1998; S. C. Hayes & Wilson, 1993),moral behavior (Hayes, Gifford, &Hayes, 1998), rule following (e.g.,Barnes-Holmes, Healy, & Hayes,2000; S. C. Hayes, Gifford, & Ruck-stahl, 1998), and verbal behavior (e.g.,S. C. Hayes & Hayes, 1992). In effect,the transfer of functions may have im-plications for a functional approach to

verbal behavior. Consider the follow-ing. The individual's behavior in theexample outlined above is likely tocome under the control of both the stopsign and the gesture from a crossingguard by virtue of the fact that thesestimuli participate in an equivalencerelation with the word "stop." Thus,the functions of the stop sign and thegesture are "discriminative-like," be-cause all the relevant functions are de-rived. That is, they are functioning asverbal stimuli (Dymond & Barnes,1997a, pp. 189-190; S. C. Hayes, Gif-ford, & Wilson, 1996; S. C. Hayes &Wilson, 1993). According to this view,verbal stimuli are those that partici-pate in derived stimulus relations andthat have theirfunctions based, in part,on the transfer offunctions. If, instead,the child had a direct history of rein-forcement for stopping in the presenceof both the stop sign and gestures fromthe crossing guard, then these stimuliwould be functioning as a discrimina-tive stimuli and the performance wouldbe entirely nonverbal. In sum, the im-plications indicate that the transfer offunctions may provide the foundationthrough which stimuli acquire novelfunctions, both adaptive and aberrant,through verbal means. Clearly, much isat stake in the study of derived stimu-lus relations and the transformation ofstimulus functions.The purpose of the present paper is

to review the research conducted todate on the transformation of stimulusfunctions in accordance with symme-try, equivalence, and other derived re-lations. In doing so we will highlight anumber of methodological issues thatwarrant further empirical study. Then,in the final section, we will outline ourreasons for adopting the generic ter-minology of relational frame theory todescribe the derived transformation ofstimulus functions. Two caveats arenecessary, however, before we begin.First, this review is by no means ex-haustive; other reviews have been pub-lished that take a somewhat differentapproach to many of the phenomenadiscussed in the present paper (see

TRANSFORMATION OF FUNCTIONS 241

A

B-C

Train function Test function

| TrainedDerived

Figure 1. A schematic representation of the de-sign of a typical transfer-of-function study. Seetext for details.

Dougher & Markham, 1994, 1996).Second, the majority of the relevant re-search conducted to date has been dis-cussed in terms of the transfer, ratherthan the transformation, of functions.Descriptions of this work in the presentpaper will remain consistent with theoriginal terminology up until our intro-duction of relational frame theory.

A DefinitionDougher and Markham (1996, p.

139) defined transfer of function as"the untrained acquisition or emer-gence of stimulus functions" that are"independent of the shared functionsthat define the class." That is, func-tions other than the conditional or dis-criminative functions of the class trans-fer from one class member to the re-maining stimuli. For example, a seriesof conditional discriminations aretrained and subsequently tested for de-rived equivalence relations (see Figure1). Then a particular behavioral func-tion is directly trained for one memberof the relation (i.e., B), and followingthis, some or all of the remaining stim-uli (i.e., C, A, etc.) are tested to see ifthey have acquired the function, with-out additional training (Figure 1). If thetrained function has transferred to theremaining stimuli in the absence of fur-

ther training, transfer of function issaid to have occurred. This outcome isbased on the trained function of B andthe derived relation between B and atleast one other stimulus.

Descriptions of transfer-of-functionresearch usually make explicit mentionof the derived stimulus relations in-volved in the transfer performance. Inthe example given above, if the trainedfunction has transferred to the remain-ing stimuli in the absence of additionaltraining, then a transfer of functionsthrough equivalence relations is said tohave occurred. Different researchershave used different terms to describethis outcome such as "transfer viaequivalence," "transfer across mem-bers of an equivalence relation," or"transfer in accordance with equiva-lence relations." It is not the intentionof the present paper to discuss the rel-ative merits of these descriptions. Thepresent paper will instead address theexisting transfer-of-function researchthrough derived stimulus relations ofincreasingly complexity, beginningfirst with derived symmetrical andequivalence relations and concludingwith multiple stimulus relations suchas sameness, more than, and less than.

TRANSFER OF FUNCTIONSTHROUGH SYMMETRY

The transfer of functions through de-rived symmetrical relations has beendemonstrated a number of times(Barnes & Keenan, 1993; Catania,Home, & Lowe, 1989; de Rose, Mc-Ilvane, Dube, Galpin, & Stoddard,1988; Dougher et al., 1994; Gatch &Osborne, 1989; Rehfeldt & Hayes,1998b), and merits a discussion sepa-rate from our more general treatmentof the transfer of functions throughequivalence relations. Recent evidencehas suggested that the relations com-prising stimulus equivalence may dif-fer systematically from one another(see Sidman & Tailby, 1982). For ex-ample, symmetry relations have beenshown to be most sensitive to changesin baseline reinforcement contingen-


cies (Pilgrim, Chambers, & Galizio,1995; Pilgrim & Galizio, 1995; Saun-ders, Drake, & Spradlin, 1999) and aremore likely to be maintained over time(Rehfeldt & Hayes, 2000). In addition,demonstrations of symmetry have beenreported in the absence of transitivityand equivalence relations until manytest trials have been presented (e.g.,Bush, Sidman, & de Rose, 1989), andresponse latency has been shown to beshorter for symmetry test trials than fortransitivity and equivalence test trials(Bentall, Dickins, & Fox, 1993; Spen-cer & Chase, 1996; Wulfert & Hayes,1988). Subjects have also been shownto estimate a greater percentage of re-inforcement for symmetry test trialsthan for transitivity and reflexivity testtrials (Pilgrim & Galizio, 1996). Find-ings such as these suggest that the re-lations defining equivalence classmembership may be construed as dif-ferent operant units (see Pilgrim &Galizio, 1996; Roche, Barnes, &Smeets, 1997; Wilson & Hayes, 1996).

Consistent with these findings, itseems plausible that results indicativeof a transfer of functions through sym-metry relations may differ from atransfer of functions through equiva-lence relations. Stimuli that are relatedsymmetrically are directly paired dur-ing training, whereas those that are re-lated via equivalence have been onlyindirectly related. Due to this contigu-ous arrangement of the stimuli duringtraining, it has been suggested that per-haps the transfer of function throughsymmetry relations should not be con-sidered genuine derived control (e.g.,Barnes & Keenan, 1993; Dougher etal., 1994). Comparing the effectivenessof function transfer between stimulithat are contiguously related duringtraining and hence directly related, andbetween stimuli that have only been in-directly related, would be worthwhileto explore.The transfer of functions through

symmetry relations is important toconsider for additional reasons. DeRose et al. (1988) found that stimulusfunctions transferred readily from con-

ditional to discriminative stimuli in theMTS paradigm, but that transfer offunctions in the opposite direction wasnot observed. In other words, the trans-fer of functions appeared to have oc-curred in one direction only (althoughthe authors do note that differences inthe number of training trials could havecontributed to this finding; see de Roseet al., p. 168). These results suggestsome similarities between the obser-vation of transfer through symmetryrelations and classical conditioning,which also occurs in one direction only(see L. J. Hayes, 1992; Rehfeldt &Hayes, 1998a). Future research direct-ed at the role of contiguity, as well thedevelopment of new procedures (e.g.,Cullinan, Barnes, & Smeets, 1997;Leader, Barnes, & Smeets, 1996), mayhelp to further disentangle the relation-ship between symmetry and transfer offunction.

TRANSFER OF FUNCTIONSTHROUGH EQUIVALENCE

The transfer of functions throughequivalence relations has been dem-onstrated with discriminative, self-dis-criminative, consequential, respondenteliciting, extinction, and sexual arousalstimulus functions in adults, children,and developmentally disabled individ-uals (e.g., Barnes & Keenan, 1993;de Rose et al., Dougher et al., 1994;Dymond & Barnes, 1994, 1997b,1998; Fields, Adams, Buffington,Yang, & Verhave, 1996; Gatch & Os-borne, 1989; Green, Sigurdardottir, &Saunders, 1991; Greenway, Dougher,& Wulfert, 1996; S. C. Hayes, Devany,Kohlenberg, Brownstein, & Shelby,1987; Lazar, 1977; Roche & Barnes,1997; Wulfert & Hayes, 1988). To il-lustrate, S. C. Hayes et al. (1987) firsttrained adults in two MTS conditionaldiscriminations (i.e., if Sample Al, se-lect Comparison B 1 and not B2; if A2,select B2 and not B 1; if Al, selectComparison C1 and not C2; if A2, se-lect C2 and not C1). Subjects werethen tested for the derivation of twoequivalence relations (Al-Bl-Cl, A2-


B2-C2). Next, a stimulus from eachequivalence relation was given a dis-tinct, simple discriminative function; inthe presence of B 1, clapping was re-inforced, and in the presence of B2,waving was reinforced. During testing,the discriminative functions assignedto the B1 and B2 stimuli transferred,through equivalence, to the C1 and C2stimuli, in the absence of differentialconsequences for either clapping orwaving in the presence of the test stim-uli (i.e., BI -* clap transferred to C1-> clap, and B2 -4 wave transferred toC2 -> wave).

METHODOLOGICAL ISSUES INTRANSFER-OF-FUNCTION

RESEARCHGiven the array of functions and

methodologies employed in transfer-of-function studies, it may be useful toconsider some of the methodologicalissues raised by the existing researchand in so doing highlight issues worthyof further empirical attention. Severalimportant issues can be identified, in-cluding the role of prior equivalencetesting, the role of instructions, exper-imental designs, and whether immedi-ate transfer was demonstrated. Weshall now address each of these in turn.

The Role of Prior EquivalenceTesting

Further investigation of the exactrole played by prior equivalence test-ing in transfer-of-function research isrequired for several reasons. First, pre-vious studies have shown that discrim-inative (Barnes & Keenan, 1993; Reh-feldt & Hayes, 1998b), self-discrimi-native (Dymond & Barnes, 1998), con-sequential (S. C. Hayes, Kohlenberg,& Hayes, 1991), and ordering (Wulfert& Hayes, 1988) functions can transferthrough equivalence relations without aprior MTS test for such relations. Suchfindings suggest that the formal dem-onstration of derived relations was notnecessary for stimulus functions totransfer. Occasionally, however, re-searchers have found it necessary to

expose subjects to either symmetry(Hayes et al., 1991) or partial equiva-lence tests (Wulfert & Hayes, 1988) tofacilitate the derived transfer perfor-mance. Thus, the specific functionsserved by testing for equivalence priorto transfer remain important empiricalissues.

Second, it has been argued that thetransfer of functions through equiva-lence relations following tests forequivalence is not reflective of genuinetransfer of function, because the B andC stimuli are directly paired in equiv-alence tests, and functions can transferthrough a second-order respondent-type process' (see Barnes & Keenan,1993; Rehfeldt & Hayes, 1998a).When a transfer of functions occurs be-tween two stimuli that have beenpaired in a prior equivalence test, it isuncertain whether the transfer has oc-curred via a derived equivalence rela-tion. That is, the transfer may have oc-curred based on the compounding ofthe B and C stimuli during equivalencetesting, and therefore would not haveoccurred had this test been omitted. Inthis way, the observed transfer effect isnot a genuine instance of derived trans-fer of functions, because it emerged viaa direct associative process (i.e., com-pounding) rather than through the der-ivation of stimulus relations (see Wul-fert, Dougher, & Greenway, 1991). Re-searchers should note that alternativeexplanations are likely when the trans-ferring stimuli were previously pairedin an equivalence testing context.

Finally, the observation that mereexposure to a series of interrelated con-ditional discriminations, without test-ing for equivalence relations, can resultin derived transfer clearly extends theanalysis and importance of the transfer-of-function effect. In the everydayfunctioning of verbal behavior, the der-ivation of stimulus relations and thetransfer of functions through these re-lations likely follows a different se-

' We are grateful to Dermot Barnes-Holmesfor a discussion of the role of associative pro-cesses in the transfer of functions.


quence to that employed in researchstudies. Further investigation of therole of prior equivalence testing wouldpermit the identification of possible fa-cilitative factors for transfer, such asthe minimum amount of conditionaldiscrimination training required, therole of nodal distance in transfer, andthe effectiveness of other, non-MTS(i.e., respondent-type) procedures ingenerating derived transfer. Because itappears that the transfer of functionsand the emergence of equivalence re-lations tend to overlap, yet can also oc-cur independently under some condi-tions (Mcllvane & Dube, 1990), anidentification of the conditions underwhich observations of both phenomenaare likely or unlikely remains an im-portant empirical goal.

The Role of Instructions

Despite the importance placed onpossible instructional effects in humanoperant research, only a few studieshave systematically examined the ef-fects of instructions on derived transfer(Dymond & Barnes, 1994, 1998;Green et al., 1991; Sigurdardottir,Green, & Saunders, 1990). In general,three main types of instructional vari-ables can be identified in transfer stud-ies. The first type of instructional var-iable involves instructions that includerelational terms such as "goes with" inthe equivalence training and testingphases of transfer studies (e.g., Fieldset al., 1996; Gatch & Osborne, 1989;Wulfert & Hayes, 1988). It has beenargued that such relational terms, com-bined with the MTS format itself, mayfunction as powerful contextual cuesfor equivalence responding in verballysophisticated subjects (Barnes &Holmes, 1991; S. C. Hayes & Hayes,1989), thus rendering any subsequentderived transfer performance ambigu-ous. Although a systematic study of in-structional variables on equivalenceclass formation has yet to be undertak-en, researchers should first consider thenecessity or extent of the instructionsprovided to subjects prior to equiva-

lence training and testing and the im-plications this may have for interpret-ing subsequent derived transfer perfor-mance.The second type of instructional var-

iable involves providing subjects withinstructions that relate the equivalenceand transfer phases of the study to eachother. For instance, Wulfert and Hayes(1988, p. 128) and Greenway et al.(1996, p. 135) instructed subjects that"all the tasks are interrelated," where-as Dougher et al. (1994, p. 334) in-structed subjects that "things that youlearn in this part of the study [equiva-lence] may be important later on."Many studies provide separate instruc-tions for different experimental phasesbut make tacit mention of the interre-lationship between training and testingphases (e.g., giving the instruction,"continue to respond in a way that youconsider correct," or "try your best,"prior to transfer-test exposure). Itseems reasonable to assume that suchinstructions might cue subjects that ac-curate responses from previous trainingphases might also be accurate upon theonset of testing phases. Subjects maythus persist with a particular responsepattern in the absence of any directfeedback. Such instruction might eitherfacilitate or inhibit derived transfer, yetno evidence exists to support one orthe other of these conclusions. Futureresearch should address the possiblefacilitative role played by these in-structions in transfer studies by elimi-nating where possible all instructionsthat relate phases of the study together,by reducing the frequency of reinforce-ment during baseline training, and byinterspersing reinforced baseline trialsbetween nonreinforced probe trialsduring the transfer test (e.g., Barnes &Keenan, 1993; Dube, Mcllvane, Ma-guire, Mackay, & Stoddard, 1989; Dy-mond & Barnes, 1997b).The final type of instructional vari-

able concerns instructions that describethe contingencies of the operant re-sponse under study (e.g., Barnes &Keenan, 1993; Dymond & Barnes,1994, 1998; Fields et al., 1996; Green


et al., 1991; S. C. Hayes et al., 1991;Rehfeldt & Hayes, 1998b). Given thenumber of different stimulus functionsthat have been studied in recent years,it is perhaps not surprising to learn thatresearchers have found it expedient toinstruct subjects regarding the particu-lar response to be trained during trans-fer-of-function training. For instance,Dymond and Barnes (1994) employedtwo complex schedule combinations togenerate two distinct patterns of re-sponding during transfer-of-functiontraining and testing. To initiate contactwith the particular schedules, one ofwhich was randomly generated on eachtrial, Dymond and Barnes instructedsubjects to "either keep pressing thespace-bar [a recycling conjunctivefixed-time 5-s fixed-ratio 1 schedule],or not press at all [a recycling con-junctive differential-reinforcement-of-other-behavior fixed-time 5-s sched-ule]. ... There is no way you can getall the space-bar tasks correct, but thebest strategy is to keep pressing onsome tasks, and on other tasks not topress at all" (1994, p. 256). Althougha further study determined that such"detailed" instructions were not nec-essary, either to initiate contact withthe schedules or to facilitate derivedtransfer (Dymond & Barnes, 1998), theprecise role played by these instruc-tions remains unclear.

Future researchers might considerthe role of instructions, both in trainingthe desired transfer of function and inmaking any speculative leaps concern-ing the implications of derived transferperformance for an understanding ofverbal behavior. This prescription isparticularly important given historicalemphases on the instructional effectsdemonstrated in seminal studies on hu-man sensitivity to changing contingen-cies (see S. C. Hayes, 1989, 1994, p.13; S. C. Hayes & Hayes, 1992; Mad-den, Chase, & Joyce, 1998). The con-cern that derived performances may, infact, be instructed is also important be-cause organisms that presumablywould not understand instructions havefailed to show derived relations (cf.

Schusterman & Kastak, 1993). A sug-gested means of avoiding potential in-terpretative difficulties in the study ofderived transfer would be to "designinstructions with parsimony as a goal"(Pilgrim, 1998, p. 33) or, if possible,not to use them at all.

Experimental Designs and Transfer-Control Procedures

Transfer-of-function studies employa number of different experimental de-signs, but the majority of studies adoptthe following three-phase sequence oftraining and testing (e.g., Barnes &Keenan, 1993; Dymond & Barnes,1994, 1998; Wulfert & Hayes, 1988).In the first phase, a minimum of twothree-member equivalence relations aretrained and tested (i.e., train A-B, A-C; test B-C). In the second phase, aparticular function is trained for onestimulus (i.e., B1 = clap) and anotherfunction is trained for a second stimu-lus (i.e., B2 = wave). Finally, in thethird phase the C stimuli are tested fora transfer of functions from the trainedB stimuli through equivalence relations(i.e., Cl = clap?/C2 = wave?).

Exceptions to the three-phase se-quence of training and testing may in-volve a reversal in the order of presen-tation of Phases 1 and 2 (e.g., S. C.Hayes et al., 1991; Rehfeldt & Hayes,1998b; Roche & Barnes, 1997), withevidence suggesting that transfer offunctions may be facilitated if the spe-cific stimulus functions are trained be-fore MTS training is conducted (S. C.Hayes et al., 1991). Similarly, re-searchers have found it expedient totest in Phase 3 for transfer to all re-maining stimuli, not just the C stimuli(e.g., Dougher et al., 1994; Green etal., 1991; Rehfeldt & Hayes, 1998b).Recently Smeets, Barnes, and Roche(1997; see also Wasserman & De-Volder, 1993) employed a novel exper-imental design to demonstrate derivedtransfer of function without symmetryor equivalence. These researcherstrained 4- and 5-year-old children toemit specific responses to pairs of in-


TABLE 1

Task sequences and examples of transfer-control procedures fortransfer-of-function research

Equivalence control Nonequivalence control Transfer baseline

Train (and test): A-B/A-X Train: B function Test: C functionTrain: B function Test: C function Train (and test): A-B/A-XTest: C function (e.g., Dougher et al., 1994; Train: B function(e.g., Barnes et al., 1995; Dymond & Barnes, 1994) Retest: C functionDymond & Barnes, 1994; (no published example)Hayes et al., 1991)

dividual stimuli (Al-Ri, B 1-Ri, A2-R2, B2-R2) in one setting (originaltraining) and to emit other responses toone member of each pair (Ai-R3, A2-R4) in another setting (reassignmenttraining). Subjects were then testedacross a number of phases for theemergence of derived stimulus-re-sponse relations (B1-R3, B2-R4), stim-ulus-stimulus relations (Al-Bl, A2-B2, B I-Ai, B2-A2), response-stimulusrelations (R3-B1, R4-B2), and re-sponse-response relations (Ri-R3, R2-R4). Modifications to the design oftransfer-of-function studies such asthose employed by Smeets et al. willinevitably contribute towards an un-derstanding of the role played byequivalence testing in generating thederived performance.

TIwo related experimental design is-sues concern the presentation of trialsfrom the above three phases and theuse of transfer-control procedures. Re-garding the first issue, transfer-test tri-als are usually presented either in dis-crete blocks (massed) or in mixedblocks including all trial types (i.e.,baseline and probe). Research compar-ing the two procedures is scarce, butthe limited evidence available doessuggest a possible facilitative effect ofmixed trial blocks on derived transfer.For example, after repeated trainingand testing with the massed arrange-ment, Barnes and Keenan (1993) ex-posed subjects to interspersed tasksand found that this facilitated derivedtransfer (cf. de Rose et al., 1988),whereas Dymond and Barnes (1997b)

employed interspersed tasks from theoutset and showed reliable transfer in2 of 3 subjects. Interspersing transfer-test trials with other trial types or al-ternating blocks of transfer-test trialswith blocks of other trial types alsoprovides a means of assessing the sta-bility of the prerequisite trained rela-tions during crucial test phases. Fromthe perspective of the subject, the suc-cessive presentation of interspersedtasks may facilitate the derivation ofrelations between the various trialtypes, which is also a common objec-tive in instructions that specify the in-terrelationship between different tasks.Further empirical and conceptual anal-yses of the facilitative effects of inter-spersed trial types in derived transferresearch are clearly needed.The second experimental issue,

transfer-control procedures, can iden-tify sources of competing stimuluscontrol in transfer studies. Surprising-ly, only a limited number of studieshave employed transfer-control proce-dures (Barnes, Browne, Smeets, &Roche, 1995; Dougher et al., 1994;Dymond & Barnes, 1994; S. C. Hayeset al., 1991, Experiment 4). Table 1shows examples of at least three pos-sible types of transfer-control proce-dures that can be employed in transfer-of-function studies. Two of the controlprocedures, equivalence and nonequiv-alence control, are designed to exam-ine the extent to which MTS equiva-lence training and testing facilitate, andare necessary for, derived transfer. Toillustrate, in their study on the transfer


of self-discrimination response func-tions through equivalence relations,Dymond and Barnes (1994) employedtwo groups of 4 subjects, experimentaland control. Subjects in the experimen-tal group were first trained in six MTStasks (Al-Bi, Al-Cl, A2-B2, A2-C2,A3-B3, A3-C3) and were then testedfor the formation of three equivalencerelations (Al-BI-Ci, A2-B2-C2, A3-B3-C3). Following successful equiva-lence performances, two self-discrimi-nation responses were trained; if thesubject had not pressed the space bar,choosing one stimulus (B1) was rein-forced, and if they did emit one ormore space-bar presses, choosing an-other stimulus (B2) was reinforced. Nonew function was trained for B3. Fi-nally, subjects were tested for a trans-fer of these self-discrimination re-sponse functions through derivedequivalence relations (i.e., no response,choose Cl; one or more responses,choose C2). Two subjects in the con-trol group were not exposed to anyform of MTS training and testing (non-equivalence control), and the remain-ing 2 subjects were exposed to MTStraining and testing that incorporatedstimuli not used during the transfer test(equivalence control: Cl and C2 werereplaced with Xl and X2 during train-ing, but C1 and C2 were used for thetransfer tests). All 4 experimental sub-jects demonstrated the predicted for-mation of three equivalence relationsand the transfer of self-discriminationresponse functions, whereas none ofthe control subjects did so. The controlprocedures employed in this study al-lowed the researchers to determine (a)that transfer of function was likely tooccur only if subjects had receivedequivalence training or testing and (b)that the equivalence relations were thenecessary relations required to showderived transfer.The third type of control procedure,

transfer baseline, involves presentingthe to-be-tested C stimuli prior to anytraining and testing in order to estab-lish a baseline from which to compare

any resulting derived effects.2 In otherwords, if the C stimuli do not evokethe behavioral function prior to train-ing but do so reliably following thetraining procedures, we can be reason-ably sure that the derived performanceis due to the training and testing pro-cedures of the study and not to someother undefined variable. To ourknowledge, no published transfer-of-function study has employed such acontrol procedure. Future researchersmight consider incorporating controlprocedures such as those outlinedabove in transfer studies.

Immediate Transfer?

Immediate transfer is defined asreaching a predetermined mastery cri-terion on the first exposure to a blockof transfer-test trials. Occasionally, thepredicted performance does notemerge on the first exposure and mayrequire repeated exposures to the train-ing and transfer-testing phases (e.g.,Barnes & Keenan, 1993; S. C. Hayeset al., 1991). Demonstrations of im-mediate transfer are important for anumber of reasons. First, immediatetransfer on unreinforced transfer-testtrials indicates that the predicted per-formances were largely derived fromthe trained relations and were not pro-duced by adventitious feedback fromthe repeated training and testing oftenused in transfer of function studies (cf.Barnes & Keenan, 1993; S. C. Hayeset al., 1991, Experiment 4). A subjectrepeatedly exposed to the transfer-testphase until the predicted performance''emerges" is likely to obtain indirectfeedback about his or her performance(i.e., "I keep getting the same prob-lems; I must be doing somethingwrong"). This inadvertent feedback,combined with the limitations of two-choice procedures (Carrigan & Sid-man, 1992) that have often been pre-sented on transfer-test trials, castsdoubt on whether any subsequent

2We are grateful to Lanny Fields for suggest-ing this procedure.


transfer performance can be consideredto be truly derived. Second, employinga predetermined stability criterion dur-ing transfer testing allows the identifi-cation of stable but unpredicted perfor-mances (Barnes & Keenan, 1993, p.63; Dymond & Barnes, 1994). A sta-bility criterion, such as selection of thesame but not necessarily predictedstimulus on at least 9 of 10 transfer-test trials, allows greater experimentalcontrol because testing will end givenany stable performance, not just thepredicted one. The inadvertent feed-back effect may, of course, still occurbefore the stability criterion isachieved. However, if stable, predictedperformances do emerge, this indicatesthat responding was largely derivedfrom the trained relations, and was notproduced by repeated transfer trainingand testing exposures. Finally, perfor-mances that fail to meet the stabilitycriterion, whether predicted or unpre-dicted, may indicate either that the nec-essary stimulus relations were notformed, in which case subjects are usu-ally returned to an earlier trainingphase, or that testing contexts inhibitedderived transfer. Given that transfer-of-function studies typically employ dif-ferent contexts for the training and test-ing of derived relations (usually MTS)and transfer (non-MTS), the identifi-cation of functional relations to explainwhy some subjects fail to demonstratetransfer is an important research topicthat warrants further empirical investi-gation (see Greenway et al., 1996).

THE TRANSFORMATION OFSTIMULUS FUNCTIONS AND

RELATIONAL FRAME THEORY"Transfer" Versus "Transformation"and the Challenge of MultipleStimulus Relations

Thus far, we have used the specificterm transfer to describe patterns of re-sponding indicative of a transfer offunctions through symmetry andequivalence relations. The relationalframe theory of complex human be-havior proposes the term transforma-

tion of stimulus functions as a genericsubstitute for transfer specifically andfor derived relational responding moregenerally (e.g., equivalence perfor-mances). According to relational frametheory, the transformation of stimulusfunctions is a defining feature of de-rived relational responding (L. J.Hayes, 1992; S. C. Hayes et al., 1996).It is important to understand that rela-tional frame theory distinguishes be-tween the general concept of transfor-mation of function and particular kindsof transformations, such as mutual en-tailment and combinatorial entailment.Mutual entailment is a generic term forrelations that have inherent bidirection-ality (e.g., if A is bigger than B, thenB is smaller than A), and combinato-rial entailment describes a combinationof relational responses (e.g., if trainedrelations exist between X and Y andbetween Y and Z, these relations will,in a given context, combine to entailrelations between X and Z and be-tween Z and X). If one stimulus in amutual or combinatorially entailed re-lation is given a direct psychologicalfunction, then the remaining stimulimay acquire this psychological func-tion, transformed in accordance withthe underlying derived relation. "Forexample, if 'lemon' is in an equiva-lence class with actual lemons in acontext that selects taste as the relevantfunction, talking of lemons can be as-sociated with salivation or puckering"(S. C. Hayes et al., 1998, p. 289).

In essence, all derived relational re-sponding involves a transformation offunctions (cf. L. J. Hayes, 1992). Re-lational frame theory contends that be-cause functions may transform in ac-cordance with a large variety of pat-terns, it is scientifically useful to dis-criminate these patterns from eachother in a relatively consistent manner.These various patterns, which are spe-cific instances of the general transfor-mation of stimulus functions, are nor-mally categorized as instances of themutually and combinatorially entailedrelations of coordination (i.e., same-ness), opposition, comparison (e.g.,


more than or less than), temporal order(e.g., before or after), and so on (see S.C. Hayes & Hayes, 1989). In effect,the observed pattern of transformationof functions defines the entailed rela-tions, and thus the entailed relations(e.g., symmetry and equivalence) donot exist as a behavioral event until aspecific transformation of functions hasoccurred.

Evidence for this approach to de-rived relational responding is accumu-lating (e.g., Barnes-Holmes, Hayes,Dymond, & O'Hora, in press; Dymond& Barnes, 1995, 1996; S. C. Hayes &Barnes, 1997; S. C. Hayes, Barnes-Holmes, & Roche, in press; Roche &Barnes, 1997; Roche, Barnes-Holmes,Smeets, Barnes-Holmes, & McGeady,2000; Steele & Hayes, 1991). In a re-cent study (Dymond & Barnes, 1995),4 experimental subjects were pretrai-ned in accordance with relations ofsameness, more than, and less than.Responding in accordance with same-ness was trained by asking subjects topick a short-line comparison given ashort-line sample in the presence of theSAME contextual cue. Responding inaccordance with more than and lessthan relations was trained using com-parisons that were either more than orless than the sample, respectively,along some physical dimension. Forexample, subjects were trained to picka two-star comparison in the presenceof a three-star sample given the LESSTHAN cue and to pick a six-star com-parison in the presence of the three-starsample given the MORE THAN cue.After the subjects had been successful-ly pretrained, they were trained in sixarbitrary relations using the three con-textual cues. The four critical relationswere [SAME] Al-B 1, [SAME] Al-Cl,[LESS THAN] Al-B2, and [MORETHAN] Al-C2, where the first termsrepresent the contextual cues, the firstalphanumeric symbol represents thesample stimulus, and the second alpha-numeric symbol represents the rein-forced or tested-for comparison choice.Subjects were then tested for seven de-rived relations, the following three re-

Trained Relations

Bi B2

Train 1 AlResponse NMFunction X

C1 C2

Derived Relations

F LBlS Test ° M

ResponseI|Function

ci C2.+ +

Test 1 Test 2Response ResponseFunction Function

Figure 2. Basic relational network adaptedfrom Dymond and Barnes (1995) showing thefour important trained relations (upper panel)and three tested relations (lower panel). LettersS, M, and L indicate the arbitrarily applicablerelations of sameness, more than, and less than.The diagram also shows that a one-responsefunction was trained using the B1 stimulus, andtests examined the transformation of the trainedself-discrimination response function in accor-dance with the relations of sameness (Cl, oneresponse), more than (C2, two responses), andless than (B2, no response). See text for details.

lations being the most important:[SAME] Bl-Cl, MORE THAN/Bi-C2, LESS THAN/Bl-B2 (see Figure2).To study derived self-discrimination

response functions in accordance withsameness, more than, and less than re-lations, three response functions wererequired. Subjects were trained usingthree reinforcement schedules to pro-duce three performances (i.e., no re-sponse, one response only, and two re-sponses only) and to choose a partic-ular stimulus after each of these per-


formances. It was predicted that if thederived sameness, more than, and lessthan relations had been established(i.e., B1 is the same as C1, C2 is morethan B1, and B2 is less than B1), andchoosing Stimulus B 1 had been rein-forced after making one response, asubject might without further training,choose (a) Cl following one response(i.e., C1 acquires the same function asB 1), (b) C2 following two responses(i.e., C2 acquires a response functionthat is more than the B 1 function), and(c) B2 following no response (i.e., B2acquires a response function that is lessthan the B1 function; see Figure 1). All4 pretrained subjects demonstrated thepredicted transformation of self-dis-crimination response functions (i.e., noresponse, choose B2; respond once,choose Cl; respond twice, choose C2).The term transformation of func-

tions was used to describe this effectinstead of transfer, because the explic-itly trained one-response function ofBl did not transfer to B2 and C2 (i.e.,B2 and C2 did not acquire one-re-sponse functions). Rather, the one-re-sponse function of B 1 transformed thefunctions of B2 and C2 in accordancewith more than and less than relations.In effect, the three distinct responsesthat emerged on the self-discriminationtests defined the multiple stimulus re-lations of sameness, more than, andless than. For relational frame theory,explanations of findings such as thesenecessitate the adoption of the termtransformation because the multiple re-sponse patterns observed defined threedistinct combinatorially entailed rela-tions (see Dymond & Barnes, 1995,pp. 182-183, for further discussion ofalternative interpretations).

The Transformation of StimulusFunctions as Generalized OperantBehavior

It is important to understand that byappealing to transformation as a ge-neric term, no kind of mediational pro-cess need be inferred (Barnes-Holmes& Barnes-Holmes, 2000; cf. Sidman,

1994, pp. 556-557). As emphasizedbefore, the derived outcomes manifeston tests for a transformation of func-tions define the entailed relations. Inthis sense transformation refers both tothe history necessary to produce a de-rived performance (i.e., a history of re-lating arbitrary stimuli in the presenceof contextual cues) and to a descriptionof the particular experimental outcome.Accordingly, relational frame theorymakes empirical predictions about thetypes of reinforcement histories nec-essary to demonstrate derived behav-ior. Approaching the study of derivedstimulus relations and the transforma-tion of functions in this way opens upthe study of derived performances toan investigation of the operant natureof relational activity in general (e.g., S.C. Hayes et al., 1996; Healy, Barnes,& Smeets, 1998). For relational frametheory, the aim is to provide an ac-count of derived relational respondingas generalized operant behavior (seeBarnes-Holmes & Barnes-Holmes,2000). Several strands of research canbe identified as supporting this dimen-sion of relational frame theory. De-rived relational responding showsmany of the properties of operant be-havior, such as development over time(e.g., Lipkens, Hayes, & Hayes, 1993),flexibility (e.g., Roche et al., 1997;Wilson & Hayes, 1996), antecedentstimulus control (e.g., Dymond &Barnes, 1995, 1996; Roche & Barnes,1997; Steele & Hayes, 1991), and con-sequential control (e.g., Healy et al.,1998). Although further empiricalwork must be conducted before the rel-ative merits of approaching relationalresponding as operant behavior can befully assessed, the evidence so far sug-gests that such an enterprise is likelyto further inform contemporary behav-ior-analytic accounts of complex be-havior.

FUTURE DIRECTIONS FORTRANSFORMATION RESEARCH

Clearly, tremendous advantages areafforded verbal humans by the trans-


formation of functions, because a widerange of seemingly generative behavioris made possible in the absence of adirect conditioning history. An appro-priate subject population with whom toexamine these advantages might beyoung children who are in the processof acquiring a range of derived behav-iors. For this reason, a potentially use-ful area of future research is the lon-gitudinal investigation of the develop-ment of derived transformation reper-toires in young children. At what pointdevelopmentally does the ability todemonstrate the derived transformationof functions through equivalence typi-cally occur, and what is the nature ofthe relationship between transforma-tion of function and other verbal be-havioral processes (e.g., rule follow-ing)? The earliest age at which a trans-formation of discriminative functionswas reported is 3 years old (Barnes etal., 1995), whereas derived symmetri-cal relations have been observed in a16-month-old infant (Lipkens et al.,1993). How much earlier might chil-dren prove to be capable of demon-strating derived transformation? Howmuch experience with function trans-formation, if any, is necessary beforestimulus equivalence and other derivedrelations can be demonstrated? Both ofthese are important empirical ques-tions.

Future research might also focus onthe stability of derived transformationeffects over time. The existing body ofevidence for the untrained acquisitionof stimulus functions is noteworthy forthe reasons discussed thus far, but un-derstanding the longevity of derivedstimulus control is also critical. Forhow long might a stimulus be shownto exert derived transformation of con-trol in the absence of contact with theoriginal training stimulus? Such a find-ing would have implications for theanalysis of clinically significant anxi-ety, which

appears to refer to avoidance responses whoseinitiating conditions are direct but very remoteand whose perpetuating conditions are mostlyderived. The life of the clinically anxious person

may be influenced by iterations and reiterationsof public and private events with reactive prop-erties traceable to initiating conditions onlythrough an almost fractal pathway involving theprocesses of stimulus generalization, derived re-lational responding, and transformation of stim-ulus functions. (Friman et al., 1998, p. 143)

The maintenance over time of manyforms of behavior, in the absence of aperiod of retraining, is highly desir-able. For example, children are likelyto learn that the spoken word "fire!"is symbolically related to an actual fire.The children may have been directlytaught that covering their mouths andexiting immediately are appropriate be-haviors when they hear another indi-vidual yell "fire!" We hope that thisdiscriminative control would transformthe functions of an actual fire, occa-sioning the same behaviors should thechildren come into contact with a realfire. Moreover, we also hope that thesetransformation effects would endurefor some time without having to retrainthe original behaviors in the presenceof the spoken word "fire!" Clearly, thedevelopment of new procedures thatmirror everyday instances of derivedrelational control, such as stability overtime, remains an important empiricalobjective.

Conclusion

Decades ago, researchers in the ex-perimental analysis of behavior lackedthe tools needed to explain novel be-haviors emitted in the absence of a di-rect history of reinforcement. In fact,at one time such observations mayhave provided fuel for the criticisms(and subsequent misrepresentations) ofradical behaviorism by other psychol-ogists; such observations seemed to re-fute the role of an organism's pastlearning history in accounting for be-havior in the present. Today, however,due to the recent research efforts froma number of laboratories, such complexbehavior can be approached and un-derstood from a behavior-analytic per-spective. We hope that this review willserve as a useful catalogue of existingstudies on the transformation of stim-


ulus functions, and that it will incitecontinued research in an attempt to un-derstand derived relational respondingand complex human behavior.

REFERENCES

Barnes, D. (1994). Stimulus equivalence andrelational frame theory. The PsychologicalRecord, 44, 91-124.

Barnes, D., Browne, M., Smeets, P., & Roche,B. (1995). A transfer of functions and a con-ditional transfer of functions through equiva-lence relations in three- to six-year-old chil-dren. The Psychological Record, 45, 405-430.

Barnes, D., & Holmes, Y. (1991). Radical be-haviorism, stimulus equivalence, and humancognition. The Psychological Record, 41, 19-31.

Barnes, D., & Keenan, M. (1993). A transfer offunctions through derived arbitrary and non-arbitrary stimulus relations. Journal ofthe Ex-perimental Analysis of Behavior, 59, 61-81.

Barnes-Holmes, D., & Barnes-Holmes, Y.(2000). Explaining complex behavior: Twoperspectives on the concept of generalized op-erant classes. The Psychological Record, 50,251-265.

Barnes-Holmes, D., Hayes, S. C., Dymond, S.,& O'Hora, D. (in press). Multiple stimulusTelations and the transformation of stimulusfunctions. In S. C. Hayes, D. Barnes-Holmes,& B. Roche (Eds.), Relational frame theory:A post-Skinnerian account ofhuman languageand cognition. New York: Plenum Press.

Barnes-Holmes, D., Healy, O., & Hayes, S. C.(2000). Relational frame theory and the re-lational evaluation procedure: Approachinghuman language as derived relational respond-ing. In J. C. Leslie & D. Blackman (Eds.),Experimental and applied analyses of humanbehavior (pp. 149-180). Reno, NV: ContextPress.

Bentall, R. P., Dickins, D. W, & Fox, S. R. A.(1993). Naming and equivalence: Responselatencies for emergent relations. QuarterlyJournal of Experimental Psychology, 46B,187-214.

Bush, K. M., Sidman, M., & de Rose, T. (1989).Contextual control of emergent equivalencerelations. Journal of the Experimental Analy-sis of Behavior, 51, 29-45.

Catania, A. C., Home, P J., & Lowe, C. F(1989). Transfer of function across membersof an equivalence class. The Analysis of Ver-bal Behavior, 7, 99-110.

Carrigan, P E, & Sidman, M. (1992). Condi-tional discrimination and equivalence rela-tions: A theoretical analysis of control by neg-ative stimuli. Journal of the ExperimentalAnalysis of Behavior, 58, 183-204.

Cullinan, V. A., Barnes, D., & Smeets, P M.(1997). A precursor to the relational evalua-tion procedure: Analyzing stimulus equiva-

lence. The Psychological Record, 48, 121-145.

de Rose, J. C., Mcllvane, W. J., Dube, W. V.,Galpin, V. C., & Stoddard, L. T. (1988).Emergent simple discrimination establishedby indirect relation to differential consequenc-es. Journal of the Experimental Analysis ofBehavior, 50, 1-20.

Dixon, M. R., & Hayes, L. J. (1999). A behav-ioral analysis of dreaming. The PsychologicalRecord, 49, 613-628.

Dougher, M. J., Augustson, E., Markham, M. R.,Greenway, D. E., & Wulfert, E. (1994). Thetransfer of respondent eliciting and extinctionfunctions through stimulus equivalence clas-ses. Journal of the Experimental Analysis ofBehavior, 62, 331-352.

Dougher, M. J., & Markham, M. R. (1994).Stimulus equivalence, functional equivalence,and the transfer of function. In S. C. Hayes,M. Sato, & K. Ono (Eds.), Behavior analysisof language and cognition (pp. 71-90). Reno,NV: Context Press.

Dougher, M. J., & Markham, M. R. (1996).Stimulus classes and the untrained acquisitionof stimulus functions. In T. R. Zentall & P. M.Smeets (Eds.), Stimulus classformation in hu-mans and animals (pp. 137-152). Amsterdam:Elsevier.

Dube, W. V., McIlvane, W. J., Maguire, R. W.,Mackay, H. A., & Stoddard, L. T. (1989).Stimulus class formation and stimulus-rein-forcer relations. Journal of the ExperimentalAnalysis of Behavior, 51, 65-76.

Dymond, S., & Barnes, D. (1994). A transferof self-discrimination response functionsthrough equivalence relations. Journal of theExperimental Analysis of Behavior, 62, 251-267.

Dymond, S., & Barnes, D. (1995). A transfor-mation of self-discrimination response func-tions in accordance with the arbitrarily appli-cable relations of sameness, more than, andless than. Journal of the Experimental Anal-ysis of Behavior, 64, 163-184 (Erratum, 66,348).

Dymond, S., & Barnes, D. (1996). A transfor-mation of self-discrimination response func-tions in accordance with the arbitrarily appli-cable relations of sameness and opposition.The Psychological Record, 46, 271-300.

Dymond, S., & Barnes, D. (1997a). Behavior-analytic approaches to self-awareness. ThePsychological Record, 47, 181-200.

Dymond, S., & Barnes, D. (1997b). Interpolat-ed training and testing and derived self-dis-crimination transfer. Experimental Analysis ofHuman Behavior Bulletin, 15, 19-23.

Dymond, S., & Barnes, D. (1998). The effectsof prior equivalence testing and detailed ver-bal instructions on derived self-discriminationtransfer: A follow-up study. The Psychologi-cal Record, 48, 147-170.

Fields, L., Adams, B. J., Buffington, D. M.,Yang, W., & Verhave, T. (1996). Responsetransfer between stimuli in generalized equiv-


alence classes: A model for the establishmentof natural kind and fuzzy superordinate cate-gories. The Psychological Record, 46, 665-684.

Friman, P. C., Hayes, S. C., & Wilson, K. G.(1998). Why behavior analysts should studyemotion: The example of anxiety. Journal ofApplied Behavior Analysis, 31, 137-156.

Gatch, M. B., & Osborne, J. G. (1989). Transferof contextual stimulus function via equiva-lence class development. Journal of the Ex-perimental Analysis of Behavior, 51, 369-378.

Green, G., Sigurdardottir, Z. G., & Saunders, R.R. (1991). The role of instructions in thetransfer of ordinal functions through equiva-lence classes. Journal of the ExperimentalAnalysis of Behavior, 55, 287-304.

Greenway, D. E., Dougher, M. J., & Wulfert, E.(1996). Transfer of consequential functionsvia stimulus equivalence: Generalization todifferent testing contexts. The PsychologicalRecord, 46, 131-144.

Hayes, L. J. (1992). Equivalence as process. InS. C. Hayes & L. J. Hayes (Eds.), Under-standing verbal relations (pp. 97-108). Reno,NV: Context Press.

Hayes, S. C. (1989). Rule-governed behavior:Cognition, contingencies, and instructionalcontrol. New York: Plenum Press.

Hayes, S. C. (1991). A relational control theoryof stimulus equivalence. In L. J. Hayes & P.N. Chase (Eds.), Dialogues on verbal behav-ior: The first international institute on verbalrelations (pp. 19-40). Reno, NV: ContextPress.

Hayes, S. C. (1994). Relational frame theory:A functional approach to verbal events. In S.C. Hayes, M. Sato, & K. Ono, (Eds.), Behav-ior analysis of language and cognition (pp.11-30). Reno, NV: Context Press.

Hayes, S. C., & Barnes, D. (1997). Analyzingderived stimulus relations requires more thanthe concept of stimulus class. Journal of theExperimental Analysis of Behavior, 68, 235-244.

Hayes, S. C., Barnes-Holmes, D., & Roche, B.(Eds.). (in press). Relationalframe theory: Apost-Skinnerian account of human languageand cognition. New York: Plenum Press.

Hayes, S. C., Devany, J. M., Kohlenberg, B. S.,Brownstein, A. J., & Shelby, J. (1987). Stim-ulus equivalence and the symbolic control ofbehavior. Revista Mexicana de Analisis de laConducta, 13, 361-374.

Hayes, S. C., Gifford, E. V., & Hayes, G. J.(1998). Moral behavior and the developmentof verbal regulation. The Behavior Analyst,21, 253-279.

Hayes, S. C., Gifford, E. V., & Ruckstahl, L. E.(1998). Relational frame theory and executivefunction: A behavioral approach. In G. R.Lyon & N. A. Krasnegor (Eds.), Attention,memory, and executive function (pp. 279-305). Baltimore: Paul H. Brookes.

Hayes, S. C., Gifford, E. V., & Wilson, K. G.

(1996). Stimulus classes and stimulus rela-tions: Arbitrarily applicable relational re-sponding as an operant. In T R. Zentall & P.M. Smeets (Eds.), Stimulus class formation inhumans and animals (pp. 279-300). Amster-dam: Elsevier.

Hayes, S. C., & Hayes, L. J. (1989). The verbalaction of the listener as a basis for rule-gov-ernance. In S. C. Hayes (Ed.), Rule-governedbehavior: Cognition, contingencies, and in-structional control (pp. 153-190). New York:Plenum Press.

Hayes, S. C., & Hayes, L. J. (1992). Verbalrelations and the evolution of behavior anal-ysis. American Psychologist, 47, 1383-1395.

Hayes, S. C., Kohlenberg, B. S., & Hayes, L. J.(1991). The transfer of specific and generalconsequential functions through simple andconditional equivalence relations. Journal ofthe Experimental Analysis of Behavior, 56,119-137.

Hayes, S. C., & Wilson, K. G. (1993). Someapplied implications of a contemporary be-havior-analytic account of verbal events. TheBehavior Analyst, 16, 283-301.

Healy, O., Barnes, D., & Smeets, P M. (1998).Derived relational responding as an operant:The effects of between-session feedback. ThePsychological Record, 48, 511-536.

Kohlenberg, B. S., Hayes, S. C., & Hayes, L. J.(1991). The transfer of contextual controlover equivalence classes through equivalenceclasses: A possible model of social stereotyp-ing. Journal of the Experimental Analysis ofBehavior, 56, 505-518.

Lazar, R. (1977). Extending sequence-classmembership with matching to sample. Journalof the Experimental Analysis of Behavior, 27,381-392.

Leader, G., Barnes, D., & Smeets, P. M. (1996).Establishing equivalence relations using a re-spondent-type training procedure. The Psy-chological Record, 46, 685-706.

Lipkens, R., Hayes, S. C., & Hayes, L. J.(1993). Longitudinal study of the develop-ment of derived relations in an infant. Journalof Experimental Child Psychology, 56, 201-239.

Madden, G. J., Chase, P N., & Joyce, J. H.(1998). Making sense of sensitivity in the hu-man operant literature. The Behavior Analyst,21, 1-12.

Mcllvane, W J., & Dube, W V. (1990). Dostimulus classes exist before they are tested?The Analysis of Verbal Behavior, 8, 13-17.

Pilgrim, C. (1998). The human subject. In K.A. Lattal & M. Perone (Eds.), Handbook ofresearch methods in human operant behavior(pp. 15-44). New York: Plenum.

Pilgrim, C., Chambers, L., & Galizio, M.(1995). Reversal of baseline relations andstimulus equivalence: II. Children. Journal ofthe Experimental Analysis of Behavior, 63,239-254.

Pilgrim, C., & Galizio, M. (1995). Reversal ofbaseline relations and stimulus equivalence: I.


Adults. Journal of the Experimental Analysisof Behavior, 63, 225-238.

Pilgrim, C., & Galizio, M. (1996). Stimulusequivalence: A class of correlations or a cor-relation of classes? In T. R. Zentall & P. M.Smeets (Eds.), Stimulus classformation in hu-mans and animals (pp. 173-195). Amsterdam:Elsevier.

Rehfeldt, R.A., & Hayes, L. J. (1998a). The op-erant-respondent distinction revisited: Towardan understanding of stimulus equivalence. ThePsychological Record, 48, 187-210.

Rehfeldt, R. A., & Hayes, L. J. (1998b). Un-trained temporal differentiation and equiva-lence class formation. The Psychological Re-cord, 48, 481-509.

Rehfeldt, R. A., & Hayes, L. J. (2000). Thelong-term retention of generalized equiva-lence classes. The Psychological Record, 50,405-428.

Roche, B., & Barnes, D. (1997). A transfor-mation of respondently conditioned sexualarousal functions in accordance with arbitraryrelations. Journal of the Experimental Analy-sis of Behavior, 67, 275-301.

Roche, B., Barnes, D., & Smeets, P. M. (1997).Incongruous stimulus pairing and conditionaldiscrimination training: Effects on relationalresponding. Journal of the Experimental Anal-ysis of Behavior, 68, 143-160.

Roche, B., Barnes-Holmes, D., Smeets, P. M.,Barnes-Holmes, Y, & McGeady, S. (2000).Contextual control over the derived transfor-mation of discriminative and sexual arousalfunctions. The Psychological Record, 50,267-291.

Saunders, R. R., Drake, K. M., & Spradlin, J. E.(1999). Equivalence class establishment, ex-pansion, and modification in preschool chil-dren. Journal of the Experimental Analysis ofBehavior, 71, 195-214.

Schusterman, R. J., & Kastak, D. (1993). ACalifornia sea lion (Zalophus californianus) is

capable of forming equivalence relations. ThePsychological Record, 43, 823-840.

Sidman, M. (1994). Equivalence relations andbehavior: A research story. Boston: AuthorsCooperative.

Sidman, M., & Tailby, W. (1982). Conditionaldiscrimination vs. matching to sample: An ex-pansion of the testing paradigm. Journal ofthe Experimental Analysis ofBehavior, 37, 5-22.

Sigurdardottir, Z. G., Green, G., & Saunders, R.R. (1990). Equivalence classes generated bysequence training. Journal of the Experimen-tal Analysis of Behavior, 53, 47-63.

Smeets, P M., Barnes, D., & Roche, B. (1997).Functional equivalence in children: Derivedstimulus-response and stimulus-stimulus rela-tions. Journal ofExperimental Child Psychol-ogy, 66, 1-17.

Spencer, T. J., & Chase, P. N. (1996). Speedanalyses of stimulus equivalence. Journal ofthe Experimental Analysis of Behavior, 65,643-659.

Steele, D., & Hayes, S. C. (1991). Stimulusequivalence and arbitrarily applicable rela-tional responding. Journal of the Experimen-tal Analysis of Behavior, 56, 519-555.

Wasserman, E. A., & DeVolder, C. L. (1993).Similarity- and nonsimilarity-based concep-tualization in children and pigeons. The Psy-chological Record, 43, 779-793.

Wilson, K. G., & Hayes, S. C. (1996). Resur-gence of derived stimulus relations. Journalof the Experimental Analysis of Behavior, 66,267-281.

Wulfert, E., Dougher, M. J., & Greenway, D. E.(1991). Protocol analysis of the correspon-dence of verbal behavior and equivalenceclass formation. Journal of the ExperimentalAnalysis of Behavior, 56, 489-504.

Wulfert, E., & Hayes, S. C. (1988). Transfer ofa conditional ordering response through con-ditional equivalence classes. Journal of theExperimental Analysis of Behavior, 50, 125-144.

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