a preliminary evaluation of the emergence of novel mand forms

A PRELIMINARY EVALUATION OF THEEMERGENCE OF NOVEL MAND FORMS

EMMA HERNANDEZ, GREGORY P. HANLEY, EINAR T. INGVARSSON,AND JEFFREY H. TIGER

UNIVERSITY OF KANSAS

Strategies that produce generalized responding are valuable, especially with regard to languageacquisition, because relatively little training may result in large behavior changes. Conditions thatresult in generalized manding were analyzed in the current study. We demonstrated in reversaldesigns that undesirable or single-word responses were the predominant mand forms of 3preschool children. Multiple baseline designs with 2 participants and a reversal design with 1participant were then used to demonstrate the extent to which differential reinforcement ofsingle-word mands (e.g., ‘‘cars’’) or framed mands (e.g., ‘‘I want the cars, please’’) would result inthe emergence of other single-word and framed mands for different items (e.g., mands for music,puppets, or puzzles). Results showed that prompting and differential reinforcement of one ortwo mand frames resulted in the emergence of other framed mands for all participants.

DESCRIPTORS: differential reinforcement, generalization, language training, mands,preschool children, tacts, verbal behavior

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Over 1 million children categorized as havingspeech and language delays were served bypublic school special education programs dur-ing the 2000–2001 academic year (NationalDissemination Center for Children with Dis-abilities, 2004). Problem behaviors are moreprevalent among children with language delaysthan typically developing children (Willinger etal., 2003). It is therefore not surprising thatprevious research has shown that many forms ofproblem behavior serve a communicative (so-cial) function (e.g., Carr & Durand, 1985;Winborn, Wacker, Richman, Asmus, & Geier,2002). Consequently, strategies have been de-veloped that replace problem behavior thatserves a social function with an acceptablealternative (e.g., Carr & Durand; Hagopian,Fisher, Sullivan, Acquisto, & LeBlanc, 1998;

Wacker et al., 1990). In essence, both theproblem and the alternative behavior arecontrolled by the same establishing operationsand consequences, and both may be understoodas mands. Skinner (1957) used the term mandto describe a verbal operant that is evoked bydeprivation or aversive stimuli (e.g., establishingoperations) and is reinforced by specific con-sequences directly related to the response. Forexample, restricted access to a preferred toytruck is likely to function as an establishingoperation for saying ‘‘truck,’’ which would bereinforced with the specific consequence ofaccess to the truck.

Single words (e.g., ‘‘truck’’) are often sug-gested as target mands for children withlanguage deficits due to the ease of productionin comparison to framed responses (e.g., ‘‘Iwant the truck, please’’; Horner & Day, 1991;Musselwhite & St. Louis, 1988), and severalstudies have shown that prompting and differ-ential reinforcement of single-word mandsresult in a reliable increase in these responses(Gobbi, Cipani, Hudson, & Lapenta-Neudeck,1986; Winborn et al., 2002; Yoder et al., 1995).Targeting single-word responses may be effi-cient in the initial stages of mand teaching, and

This project was completed as partial fulfillment of therequirements for a Master of Arts degree by the firstauthor. We thank Rachel H. Thompson and James A.Sherman for their helpful comments on an earlier versionof this manuscript.

Reprints may be obtained from Gregory P. Hanley,Applied Behavioral Science Department, University ofKansas, 4023 Dole, Lawrence, Kansas 66045 (e-mail:[email protected]).

doi: 10.1901/jaba.2007.96-05

JOURNAL OF APPLIED BEHAVIOR ANALYSIS 2007, 40, 137–156 NUMBER 1 (SPRING 2007)

137

may be especially important if those mands arebeing taught as functionally equivalent replace-ments for problem behavior (Carr & Durand,1985; Fisher et al., 1993; Horner & Day;Wacker et al., 1990). However, the samestrategy may be inefficient in the long term,because it is likely that each new mand wouldrequire separate instruction prior to acquisition.Thus, it may be important that mand training,whether as an intervention for a preexistingpattern of socially mediated problem behavioror as a means to preempt the development ofthis sort of behavior, contain features that allowthe development of mands that are not directlytrained.

Strategies to promote generalization werefirst described by Stokes and Baer (1977), whosuggested that generalization should be directlyassessed and carefully programmed. Althougha variety of procedures have been found to beeffective for strengthening verbal repertoires (seeWarren & Reichle, 1992, for a review), rela-tively few studies have determined the teachingconditions that will result in generalization.One possible reason for this relative lack ofresearch is that similar responses may havedissimilar controlling variables. For instance,several researchers have shown that mands andother verbal operants (e.g., tacts) are function-ally independent (Hall & Sundberg, 1987;LaMarre & Holland, 1985; Sigafoos, Doss, &Reichle, 1989), and that teaching a child tolabel (i.e., tact) an item will not necessarilyresult in that child being able to request (i.e.,mand) that item when it may be important forthe child to do so. In contrast, more recentresearch (Petursdottir, Carr, & Michael, 2005)has shown that mands and tacts are notnecessarily independent. Petursdottir et al.showed that mand training tended to lead toemergent tacting, and tact training resulted insome emergent manding. Although this studysuggests that mand training leads to emergenttacting, variables that effect transfer betweenmands and tacts have not been identified. Thus,

an important research area involves understand-ing the conditions under which generalizationbetween verbal operants (e.g., tacts and mands)will occur or, from an applied perspective,identifying the procedures that can producegeneralization between verbal operants.

Wallace, Iwata, and Hanley (2006) recentlyshowed that transfer from tact to mandfunctions was dependent, at least in part, onthe value of the items to be tacted and manded.That is, if the items were shown to be highlypreferred, mands for these items occurred andwere maintained following tact training. Anadditional strategy for promoting transferamong verbal operant classes was offered bySkinner (1957), who suggested that the use ofa frame might facilitate generalization to un-trained responses (e.g., the mand frame, ‘‘I wantthe —,’’ or the tact frame, ‘‘That is a —’’). Amand frame may serve to bridge tacts andmands. That is, a mand frame may serve tomediate generalization (Stokes & Baer, 1977) inthat the response, ‘‘I want the —, please,’’would be taught in the presence of a strongestablishing operation. This frame may thus beevoked in the presence of other similar estab-lishing operations, thus resulting in generaliza-tion. For example, a child may be taught to say,‘‘I want juice, please’’ when thirsty and maysubsequently use a frame to mand for foodwhen hungry (e.g., ‘‘I want cookies, please’’).Such outcomes were suggested by Hart andRisley (1980), who showed that an experimen-tal group who were taught to use compoundsentences to access restricted toys used morecomplex vocabulary and sentence structure thathad not been directly taught than the compar-ison group did.

Simic and Bucher (1980) provided anexample of teaching mands within frames whenthey taught 5 children with mental retardationthe partial frame, ‘‘I want a —.’’ Their datashowed that mand frames were acquired bythe participants, but the benefit of gener-alized manding via framed mands was not

138 EMMA HERNANDEZ et al.

demonstrated. Therefore, further analysis of theconditions in which teaching framed mandsresults in generalization to untrained mandsseems warranted.

In the current study we first determined thepredominant mand forms for 3 preschool-agedchildren who appeared to be at risk for languagedelays. We then determined the direct andindirect effects of providing differential re-inforcement for relatively smaller or largertopographical mand classes. More specifically,once we identified a variety of preferred itemsand determined that tacting repertoires for theseitems were intact, we evaluated the extent towhich training both single-word mands (e.g.,‘‘truck’’) and framed mands (e.g., ‘‘I want thetruck, please’’) would result in the emergence ofnovel mands.

GENERAL METHOD

Assessment and Training Overview

A preference assessment (Fisher et al., 1992)was conducted with each participant to identifypreferred items that would maximize themotivating conditions of the mand analysis(Wallace et al., 2006). A tact assessment wasconducted to ensure that the participants wereable to tact each of the items that were to beincluded in the mand analysis, and tact trainingwas provided when the participant was not ableto tact a preferred item. Thus, items that thechildren preferred and could tact were includedin the mand analysis. The initial mand analysisidentified the particular response forms thatfunctioned as mands (referred to as the mandform analysis). These data were then used asbaselines to evaluate the direct and indirecteffects of teaching single-word and framedmands (referred to as the generalization analy-sis).

Participants and Setting

Two 4-year-old-boys (Tom and Jason) withnonspecific developmental delays and 1 1.7-year-old typically developing girl (Ana)

participated in this study. All 3 childrenattended a classroom in a full-day inclusivepreschool program. They were selected toparticipate in this study because they madefew vocal requests in the classroom, andteachers reported that their communicationconsisted primarily of gestures, crying, andtaking items from children and adults.

The preference assessments and mand formand generalization analyses were conducted ina room (2.3 m by 2.7 m) that contained a child-sized table, two child-sized chairs, five plasticopaque containers, and two bookshelves. Thetact assessment and training were conducted ina classroom (12 m by 7 m) that containeda variety of recreational activities.

Data Collection, Target Behaviors, andInterobserver Agreement

During the preference assessment and tactassessment, trial-by-trial data were collected onthe child’s approach toward an item or vocalapproximation of the name of the item,respectively. An approach was defined as reach-ing toward the item with one or both hands.During the tact assessment, a correct responsewas scored when the child’s vocal responseapproximated the agreed-upon name of theitem; an incorrect response was scored when thechild did not make a vocal response within 5 sor when the vocal response did not resemble thename of the item. The relevant tacts for eachchild are listed in Table 1.

During each preference and tact assessment,data were collected using paper and pencil andwere summarized as the percentage of trials onwhich an item was selected (preference assess-ment) or the number of correct responses overthe total number of trials conducted (tactassessment and training). Interobserver agree-ment was assessed by having two observerssimultaneously but independently record selec-tions (preference assessment) and correct orincorrect responses (tact assessment) on a trial-by-trial basis. Agreements were defined as bothobservers scoring the same response during each

NOVEL MAND FORMS 139

trial. Agreement for each session was calculatedby dividing the total number of agreements bythe total number of agreements and disagree-ments and multiplying by 100%. Agreementwas assessed during at least 50% of preferenceassessment sessions across all participants andaveraged 98% (range, 96% to 100%). Agree-ment was assessed during at least 75% of tactassessment and training sessions across allparticipants and averaged 94% (range, 73% to100%).

The frequency of each participant’s undesir-able, single-word, and framed responses wasrecorded during the mand form and general-ization analyses. Undesirable responses for Anawere crying, yelling, and two rudimentary signsdefined as placing an open palm on her chestand moving it from side to side (similar to theAmerican sign language sign for ‘‘please’’) orextending her arms toward the items whilemaking contact with the fingertips of bothhands (similar to the sign for ‘‘more’’). Theundesirable response form for Tom and Jasonwas pointing, which was defined as extendingthe index finger in the direction of the item.These responses were considered undesirablebecause all participants showed evidence ofsomewhat intact vocal verbal repertoires; thus,these responses may have competed with further

development of their vocal verbal repertoires.Because single-word mands, as opposed toundesirable behavior, were found to be thepredominant mand form for Jason, undesirableresponses are not reported in the generalizationanalysis. Single-word responses were defined asvocalizations that included an approximation ofthe name of the target item (e.g., ‘‘dinosaurs,’’‘‘dino,’’ or ‘‘want dino’’) and did not includea mand frame. Framed responses were definedas vocalizations taking the form of ‘‘I want[name of the object], please,’’ ‘‘May I have[name of the object], please?’’ or ‘‘Can I have[name of the object], please?’’ Single-wordresponses were not scored in the same instancea framed response occurred (i.e., single andframed responses were mutually exclusivecategories).

During the mand form and the generaliza-tion analyses, data on child behavior werecollected using handheld computers duringcontinuous 10-s intervals and were summarizedas the number of responses per minute.Interobserver agreement was assessed in at least49% of mand form analysis sessions across allparticipants and averaged 98% (range, 87% to100%). Agreement was assessed in at least 22%of the generalization analysis sessions across allparticipants and averaged 98% (range, 64% to

Table 1

Tacts and Item Descriptions

Child Tacts Items

Ana Frog, froggies Four beanbag frogs and a rubber frogBabies, girl, doll, bottle One 20-in. doll, one 8-in. crying and laughing doll with a bottle and blanket,

and one 5-in. musical dollPhone, telephone Six plastic phones with sounds and music buttonDinosaur, dino Plastic LegoH dinosaurs and a plastic dinosaur with sounds and a lightCars, train, bus Plastic cars with sounds and lights, a bus and a train

Tom Cars Five cars of various colorsDress-up Scarves, necktie, necklaces, a vest, dresses, bracelets, glasses, two hats, a ring, and shoesDisneyH Plastic AladdinH and Pooh BearH movie charactersBooks Paperback preschool books such as Tonka TrucksH and a bookDinosaurs Plastic LegoH dinosaurs and a plastic dinosaur with sounds and a light

Jason Music Drum, metal triangle, xylophone, clapper, cymbals, and rhythm sticksPuppet Animal hand puppetsBears Colorful plastic stackable bearsDinosaurs Plastic LegoH dinosaurs and a plastic dinosaur with sounds and a lightPuzzles Electronic inset puzzle with sounds


100%). Exact agreement scores were calculatedon an interval-by-interval basis by dividing thenumber of intervals with agreements by thenumber of intervals with agreements anddisagreements; these fractions were then aver-aged and multiplied by 100%. An agreementwas scored for each interval if both observersrecorded the same number of responses.

PREFERENCE ASSESSMENT AND TACT ASSESSMENT

AND TRAINING

The purpose of the preference assessment andthe tact assessment and training was to identifyfive items to be included in the mand analysis.Items to be included met three criteria: (a)When provided with the item following anapproach response during the preference assess-ment, the child engaged with the items for theentire 30-s period in a developmentally appro-priate manner (showing the absolute value of anitem). (b) The child could tact the items inthree consecutive opportunities during the tactassessment or following tact training (showinga minimal tact repertoire with respect to theitems). (c) The items were selected over otheritems on at least some of opportunities(showing the relative value of the item).

Procedure

Preference assessment. Interviews of parentsand teachers yielded a list of 10 preferred itemsfor each child. A paired-choice preferenceassessment (Fisher et al., 1992) was conductedwith each participant to identify five items foruse during the mand analysis. Each item waspaired with every other item once during theassessment. This occurred by placing two bins,each containing different sets of items, on thetable simultaneously. The child’s approachtoward one of the two bins (e.g., a bincontaining cars and a bin containing dinosaurs)resulted in 30-s access to that bin. When a childapproached two bins simultaneously, the ther-apist blocked access to the bins, and the binswere presented again. The percentage of trials inwhich items were selected was calculated by

dividing the number of times the child selectedan item by the total number of trials in whichthe item was presented and then multiplying by100%.

Tact assessment and training. Each child’sability to tact each of the 10 items was assessedby asking the child, ‘‘What is this?’’ in thepresence of each item. Following a correctresponse, the therapist provided social praise(e.g., ‘‘That’s right!’’). Incorrect responsesresulted in a brief 2-s time-out from interactionfollowed by the presentation of the next item.The therapist presented each of the 10 items ina random order, and each item was presentedthree times (for a total of 30 tact trials perchild). If the child did not accurately tact thetarget items in all three of the opportunities,tact training was conducted.

Tact training was conducted in a mannersimilar to the tact assessment except that if thechild did not respond within 5 s or respondedincorrectly, the therapist repeated the questionand simultaneously provided a model prompt.For example, the therapist asked, ‘‘What isthis?’’ and then immediately stated, ‘‘This isa car, say car.’’ If the child imitated thevocalization within 5 s of the model, socialpraise was provided. On the next trial, theprompt was delayed by 2 s. For example, thetherapist said, ‘‘What is this?’’ and waited 2 s,before stating, ‘‘This is a car, say car.’’ Themodel prompt was delayed by increments of 2 sfollowing each correct response (Ault, Gast, &Wolery, 1988). Tact training was terminatedwhen the child independently (i.e., in theabsence of a model prompt) responded correctlyfor three consecutive trials.

MAND FORM ANALYSIS

The purpose of the mand form analysis wasto identify the response forms that functionedas mands for each child. Five 3-min sessionswere conducted daily, 4 to 5 days per week.Each of the 3-min sessions involved one of thefive sets of items that the child was able to tact


and had been selected on over 20% ofopportunities. The presentation of the itemswas conducted in random order for Tom.However, to determine if a temporal general-ization gradient of novel mand forms woulddevelop (i.e., if untrained mands that wereassessed closer in time to directly trained mandswould emerge sooner than mands that wereassessed later), the order in which the itemswere presented was held constant for Ana andJason. Brief breaks were provided between eachsession such that the total amount of time spentin sessions each day was approximately 20 minfor all participants.

Procedure

Noncontingent reinforcement (NCR). DuringNCR, one of the five sets of items was freelyaccessible for 3 consecutive minutes. At the endof the 3-min session, the items were returned tothe bin and placed out of view. A total of fivesessions (i.e., one session per toy set) wereconducted consecutively, and only one set ofitems was presented at a time. The therapist didnot respond in any way to the target responsesor other behaviors during these sessions.Because Ana rarely experienced periods inwhich an adult who was in close proximitydid not interact with her for minutes at a time,she was also provided with 10 s of attentionevery 30 s, independent of her behavior.During this condition, the establishing opera-tion for manding for the toy sets was eliminatedor at least minimized by providing continuousaccess to the preferred items. Therefore, thiscondition served as a control for the effects ofdifferential reinforcement.

Differential reinforcement of undesirable, sin-gle-word, or framed mands (DRA). The DRAcondition was similar to the NCR conditionexcept that the items were placed on the tablebut out of the child’s reach, and access to theitems was provided for 30 s following anytarget response. That is, to increase the rate ofthe target response that functioned as theparticipant’s predominant mand, undesirable,

single-word, or framed responses resulted inbrief (e.g., 30-s) access to the bin of items.

Experimental Design

A reversal design was used to identify theresponse forms maintained by access to thetarget items (i.e., mands). For Ana, this analysisbegan with the DRA condition due to signif-icant changes in the definition of her undesir-able responses that occurred in previous (un-reported) observations during NCR and DRAsessions.

GENERALIZATION ANALYSIS

Procedure

The purpose of the generalization analysiswas to determine if differential reinforcement ofsingle-word and framed mands would result ingeneralization to single-word or framed mandswith no explicit training. The NCR and DRAconditions from the mand form analysis servedas baselines for all 3 children for the general-ization analysis.

Differential reinforcement of single-word andframed responses (DRSF). This condition wasimplemented with Ana and Tom only becausetheir mand form analysis showed that undesir-able mands were their predominant mandforms. Thus, the DRSF condition restrictedthe contingency class that received reinforce-ment to single-word and framed responses. Inother words, this condition was similar to theoriginal DRA condition described above, exceptthat access to the visible item was not providedif the child engaged in an undesirable response.A model of the single-word mand was providedafter the initial 30 s had expired following thepresentation of the item or when the child hadnot emitted a single-word or framed responsefor 5 s following removal of the items. Promptdelays were then used to eliminate thevocal model prompts. One second was addedto the 5-s delay following a correct responseand 1 s was subtracted from the delayfollowing an undesirable response. When vocalmodel prompts had been eliminated for three


consecutive sessions (i.e., independent respond-ing occurred), vocal mand models were notprovided in subsequent sessions.

Differential reinforcement of framed responses(DRF). Differential reinforcement of framedresponses was implemented when Ana and Tomreliably engaged in single-word mands on oneof the baselines that had previously beenexposed to the DRA or DRSF conditions, andthe indirect effects of that behavior change wereincomplete (e.g., undesirable behavior persistedon the remaining baselines). DRF was imple-mented with Jason to increase the developmen-tal appropriateness of his manding repertoire.This condition was similar to the DRSFcondition, except that a framed mand modelwas provided after the initial 30 s had expired,and access to the preferred item was providedonly following framed responses (i.e., undesir-able responses and single-word mands wereplaced on extinction). Prompting, promptdelays, and mand models were arranged asdescribed above.

Experimental Design

The direct effects of the restricted differentialreinforcement contingencies were demonstratedin multiple baseline designs across behaviors forAna and Tom and in a reversal design withJason. Although multiple baselines were used toobserve the indirect effects of the restricteddifferential reinforcement procedures for allparticipants, experimental control over theindirect effects of the differential reinforcementcontingencies was shown only with Jason ina reversal design.

RESULTS AND DISCUSSION

Preference Assessment and Tact Assessmentand Training

Items included in the mand analysis metthree criteria described above. Results obtainedfrom the preference assessment are shown inFigure 1 as the percentage of trials in whicheach item was selected. In general, preferenceassessment data show a descending slope, thus

indicating that some items were more preferredthan the other items included in the assessment.

Results obtained from the tact assessmentand training are shown above the bars onFigure 1. Ana tacted four of the items (tele-phones, dinosaurs, frogs, and babies) on allthree trials and appropriately interacted withthese materials during the preference assessment(data available from the second author);therefore, these items were included in hermand analysis. Ana did not engage with thepens appropriately, so they were not included inthe mand analysis. She tacted cars in at least oneof three trials; therefore, cars were selected forinclusion as her fifth toy set. Thirteen trials wererequired to teach Ana to tact cars on threeconsecutive opportunities (data not shown).Tom tacted cars, dinosaurs, and books in atleast one of the three trials and appropriatelyengaged with these materials during the prefer-ence assessment; therefore, these items wereincluded in his mand analysis. Three, 11, and15 trials were required to teach Tom to tactcars, dinosaurs, and books, respectively, onthree consecutive opportunities (data notshown). Tom appropriately engaged with theDisneyH and dress-up toys; therefore theseitems were also included as the fourth and fifthtoy sets. Fifteen and 18 trials were required toteach Tom to tact DisneyH and dress-up,respectively, on three consecutive opportunities(data not shown). Jason tacted puppets, bears,puzzles, and dinosaurs on all three trials andappropriately engaged with these materialsduring the preference assessment; therefore,these items were included in his mand analysis.Jason did not engage with the necklaces orbooks appropriately; therefore, music wasselected for inclusion as his fifth toy set. Sixtrials were required to teach him to tact thisitem on three consecutive opportunities (datanot shown).

Mand Form Analysis

The results of the mand form analysis forAna are shown in Figure 2. The mean rate of


undesirable responses was highest during thefirst DRA condition (M 5 0.9) across all items(i.e., cars, dinosaurs, frogs, babies, and phones).Single-word responses were also observedduring DRA (M 5 0.4 across all items), butto a much lesser extent than undesirableresponses. During the NCR condition, noundesirable responses occurred, but single-wordresponses occurred intermittently across all five

items (M 5 0.3). The rate of undesirableresponses increased during the return to DRA(M 5 0.8 across all items), and single-wordresponses persisted at similar, albeit highlyvariable, rates (M 5 0.7 across all items).Framed responses were not observed in anycondition with Ana.

Low and inconsistent rates of undesirable(M 5 0.3) and single-word (M 5 0.1)

Figure 1. Percentage of trials in which items were selected during the stimulus preference assessment for Ana (top),

Tom (middle), and Jason (bottom).


responses occurred during the initial NCRcondition for Tom across each of the fivebaselines (i.e., cars, dress-up, DisneyH, dino-saurs, and books) (Figure 3). DuringDRA, high and persistent levels of undesirableresponses occurred (M 5 1.4), whereas single-word responses occurred during only oneof the 20 sessions. During the return to

NCR, undesirable responses were zero in 14of the 15 sessions across the five baselines,and single-word responses occurred at lowand intermittent rates (M 5 0.1). Upon thereturn to the DRA condition, undesirableresponses increased (M 5 1) and single-word(M 5 0.1) and framed (M 5 0) responsesdid not.

Figure 2. Independent target responses per minute forAna during the mand form analysis.

Figure 3. Independent target responses per minute for

Tom during the mand form analysis.


NCR resulted in either low or zero rates ofall target responses across each of the fivebaselines (i.e., music, puppets, bears, dinosaurs,and puzzles) for Jason (Figure 4). That is,the mean rate of responding for undesirable,single-word, and framed responses was 0, 0.3,and 0 responses per minute, respectively.During the DRA condition, single-wordresponses occurred consistently in all sessions(M 5 1.7), undesirable responses occurred atvariable rates in just over half of the sessions(M 5 0.8), and framed responses were notobserved. When NCR was reinstated, the rateof undesirable responses continued to be vari-able (M 5 1.8), whereas the consistent rate ofsingle-word responses observed during DRAwas disrupted (M 5 0.6). The return to DRAresulted in stable rates of single-word responsesacross all baselines (M 5 1.9) and inconsistent,and at times high, rates of undesirable behavior(M 5 1.7).

The results of the mand form analysisshowed that Ana’s and Tom’s preexistingand predominant mand forms were undesirableresponses, given that they appeared to bemost sensitive to the changes in the relevantcontingencies. By contrast, single-word re-sponses appeared to be most sensitive to thecondition changes for Jason and appeared tobe his predominant mand form. Althoughall target responses would have resulted inaccess to the toy bins during the DRAcondition, less desirable mand topographiesemerged for each child: rudimentary signsfor Ana, pointing for Tom, and uttering singlewords for Jason. That is, by programminga broad differential reinforcement contingency(i.e., one that provided reinforcement forseveral categories of responding sequenced on adevelopmental continuum), the predominantmand form was identified for each child acrossall item sets. For all participants, the respectivemand forms possessed strong generality assimilar topographies of manding were observedin the DRA condition across all baselines.

Although reliable patterns of one of thetopographical classes were evident from themand form analysis for each child, there wassome variability in the data that deservescomment. The establishing operation for

Figure 4. Independent target responses per minute forJason during the mand form analysis.


manding as well as the relevant differentialreinforcement were absent from the NCRcondition. Therefore, target responses thatoccurred in the NCR condition likely did notfunction as mands. In addition, when access tothe bin was provided for 30 s during the DRAcondition following a target response, therelevant mand contingency was temporarilyabsent from this condition as well. Therefore,a change in the rate of topographical classes ofbehavior across conditions was the criticalindicator of the predominant mand form; themere occurrence of behavior in either conditiondid not necessarily support or negate thepossibility of that particular topography func-tioning as a mand. Due to the free-operant (asopposed to trial-based) nature of this assess-ment, there were many opportunities for thetarget responses to be emitted under conditionsin which tact-like controlling variables werepresent. For instance, when Ana was playingwith the babies she often looked towards theexperimenter and said ‘‘babies’’ while extendingthe baby towards the experimenter. Althoughresponses like this did not result in anygeneralized reinforcer, their occurrence seemedto be controlled by the presence of the objectand perhaps a history of social reinforcementunder similar conditions.

The persistence of Ana’s and Tom’s undesir-able mand forms suggests that the ability to tactitems may not have been sufficient to occasionsingle-word mands for the same items in thepresence of specific establishing operations. Theresults for Ana and Tom are consistent withthose of Hall and Sundberg (1987), who foundthat generalization from tact to mand contin-gencies failed to occur following the manipula-tion of establishing operations for already-learned tacts. The opposite was true with Jason,for whom a tact repertoire, taught immediatelyprior to the mand form analysis, was sufficientfor occasioning single-word mands. Wallace etal. (2006) suggested that transfer from tact tomand repertories may be facilitated by the

inclusion of highly preferred items during tacttraining. Several of the items included for Tomand Jason were highly preferred, yet transferfrom tact to mands occurred only for Jason.

There were, however, differences in thecontingencies between this and the Wallace etal. (2006) study. Specifically, the contingency inthe Wallace et al. investigation was restricted toone target class. It is possible that the broaddifferential reinforcement contingency arrangedin the current study, which provided reinforce-ment for undesirable behavior as well as vocalmands, prohibited the emission of single-wordresponses for Tom and Ana. In addition toassessing or teaching mands under properlymotivating conditions, the data from our mandform analysis suggest that restricting the class oftopographies that receive reinforcement (i.e.,programming extinction for less desirabletopographical classes) may be necessary totransfer control from tacts to mands.

Therefore, the contingency classes were sys-tematically narrowed in the mand generalizationanalysis. That is, fewer topographies of behaviorresulted in access to the toy bins. For example,initially Ana was provided with access to the carswhen she engaged in an undesirable, single-word,or framed mand. These three responses were partof the same contingency class in that theyfunctioned as mands to access the cars. In themand generalization analysis, this contingencyclass was narrowed and included only single-wordand framed responses (e.g., DRSF). The contin-gency class was narrowed further in the DRFcondition in that only framed mands resulted inaccess to the cars. These changes were imple-mented to increase the complexity and socialdesirability of the mands and to determine theextent to which the development of the morecomplex forms of manding would result intransfer to untrained stimuli.

Generalization Analysis

Figure 5 shows Ana’s rates of undesirable,single-word, and framed mands across sessions


for the five baselines of different sets of toys(e.g., cars, dinosaurs, frogs, baby, and phones).It should be noted that the initial NCR andDRA data presented in Figure 5 are also shownin Figure 2 and are presented here as a baseline

for the generalization analysis. Differentialreinforcement was provided for single-wordand framed mands only (DRSF) on the carsbaseline. During DRSF, the mean rate of single-word mand models provided per session was

Figure 5. Independent target responses per minute for Ana during the generalization analysis.


0.1. The mean rate of single-word mandsincreased slightly to 2.4 compared to the meanrate of 1.6 during DRA. In addition, thereappeared to be an indirect effect of the DRSFcontingency on the other four baselines. Thatis, during DRA (Sessions 6 to 14), the meanrates of single-word manding for dinosaurs,frogs, babies, and phones were 0.5, 0.3, 0.6,and 0.3, respectively. However, followingimplementation of the DRSF contingency forcars, single-word manding increased fordinosaurs, frogs, babies, and phones to 1.6,1.0, 1.7, and 1.5, respectively. In addition,undesirable responses increased from a meanrate of 0.8 in the DRA condition to 1.3throughout all four baselines even when thesebehaviors were placed on extinction in the carsbaseline. Single-word mand models were pro-vided throughout this phase on the cars baselinebecause vocal models had not been eliminatedfor three consecutive sessions; thus, indepen-dent responding throughout the session had notoccurred.

Because the indirect effects of the DRSFcontingency were observed across all fourbaselines, DRSF was introduced simultaneouslyacross the remaining four baselines to strength-en the single-word mands and eliminate un-desirable mands via extinction. The mean rateof single-word mand models provided persession was 0.6, 0.8, 0.4, 0.6 for dinosaurs,frogs, babies, and phones, respectively. WhenDRSF was implemented across all baselines(Sessions 35 to 43), undesirable mandingdecreased to near zero (M 5 0.6). Next, thedifferential reinforcement contingency was nar-rowed to include only framed responses on thecars baseline. During this phase, framed mandmodels were provided at a rate of 0.5 persession. In addition, on the other four baselines(e.g., dinosaurs, frogs, babies, and phones),independent single-word manding occurred forthree consecutive sessions; thus, single-wordmand models were eliminated (asterisks inFigure 5). The DRF contingency resulted in

a gradual increase in framed mands (M 5 1.3),yet single-word mands (mands outside frames)persisted at a mean rate of 3.4. The asteriskbelow Session 67 denotes that framed mandmodels were eliminated at this point. Instancesof framed mands were also observed on thefrogs, babies, and phones baselines. Because thegeneralization of framed mands was incomplete,DRF was then implemented on the nextbaseline (dinosaurs). Framed mand modelswere provided at a rate of 0.5 per session.Following the implementation of the DRFcontingency, an immediate increase in framedmands (M 5 1.4) occurred on this baseline.The asterisk above Session 100 denotes thepoint at which mand models were eliminated.Two other important changes in respondingoccurred when the DRF contingency wasimplemented on the second baseline: (a) Therate of single-word mands decreased on allfive baselines (M 5 1.1), and (b) there wasan increase in the rate of framed mandsthat occurred on the three baselines inwhich the contingency had not been narrowed(M 5 0.7).

In summary, Ana’s data show both direct andindirect effects of narrowing the contingencyclass on mand forms. The direct effects of theDRSF condition were subtle (a slight rateincrease in single-word mands was observed),and the direct effects of the DRF contingencieswere delayed (seven sessions occurred beforeconsistent rates of framed mands were ob-served). However, the indirect effects ofrestricting the contingency to single-word andframed mands were robust in that single-wordmands also occurred at high levels across thefour baselines in which the contingency re-mained unchanged. The indirect effects of theDRF contingency were subtle until it wasimplemented on the second baseline. In otherwords, once two of the five baselines involveda contingency in which reinforcement wasprovided only for framed mands, framed mandswere observed on all baselines and single-word


mands decreased to near zero, even though theycontinued to be reinforced in the majority ofthe baselines.

A limitation of Ana’s data is that functionalcontrol over most of the direct and indirecteffects was not demonstrated. The direct effectsof the DRF contingency were replicated ina multiple baseline design, but the direct effectsof the DRSF contingency were not replicatedbecause of the apparent indirect effects of thiscontingency. Nevertheless, Ana’s data providesome evidence that a more socially desirable andcomplex mand repertoire may result fromrestricting contingency classes in a limitednumber of situations.

Figure 6 shows Tom’s rates of undesirable,single-word, and framed mands across sessionsfor the five baselines (e.g., cars, dress-up,DisneyH, books, and dinosaurs) that includeddifferent sets of toys. As with Ana, the NCRand DRA data were obtained from the initialmand analysis. When the DRSF contingencywas implemented on the cars baseline, undesir-able manding initially increased but thendecreased to baseline levels (M 5 1.8), andsingle-word manding increased slightly (M 5

0.8). Single-word mand models were providedat a rate of 0.4 per session. The asterisk aboveSession 20 denotes that mand models wereeliminated for the cars baseline. Unlike theeffect observed with Ana, the indirect effects ofthe DRSF contingency were minimal. Somesingle-word manding occurred on the booksbaseline (M 5 0.5; Sessions 13 to 22), butotherwise, undesirable manding persisted fordress-up, DisneyH, and dinosaurs (M 5 1.2).The DRF condition was then implemented onthe first baseline (cars), and a gradual increase inframed manding was observed on the carsbaseline (M 5 1.6) along with a slight decreasein undesirable responses (M 5 1.2) and single-word mands (M 5 0.5). Framed mand modelswere provided at a rate of 0.7 per session andwere eliminated beginning with Session 31.Although undesirable manding (M 5 1.1)

persisted on the other four baselines (i.e.,dress-up, DisneyH, books, and dinosaurs),instances of framed mands also were observedon all four baselines. DRSF was then imple-mented on the second baseline (dress-up).Single-word mand prompts were provided ata rate of 0.7 per session and were eliminatedbeginning with Session 41. Although single-word mands increased on the second baseline(M 5 0.5; Sessions 36 to 43), single words werenot observed in those baselines in which theoriginal DRA contingency was operating (M 5

0.2). Therefore, DRF was implemented on thesecond (dress-up) baseline (Sessions 44 to 52).Framed mand models were provided at a rate of0.3 per session and were eliminated beginningwith Session 49. Direct effects were observed inthat framed mands (M 5 1.3) for dress-upbegan to occur consistently. We also observedindirect effects in that framed mands occurredon the books (M 5 1.0) and dinosaurs (M 5

0.5) baselines in which the original contingencyremained unchanged. DRF was implementedon this third baseline (DisneyH), and framedmands (M 5 1.6) were acquired for these toys.Framed mand models were provided at a rate of0.1 per session and were eliminated beginningwith Session 59.

In summary, single-word mands were con-sistently observed with Tom only whenprompting and differential reinforcement werearranged. Thus, in contrast to the resultsobserved with Ana, there did not appear to bea consistent indirect effect of the single-wordmand training. Differential reinforcement offramed mands resulted in an increase in thetarget mand and first-time instances of framedmands for dress-up, DisneyH, and dinosaurs,suggesting that direct training of a mand framemay result in the emergence of framed mandsfor other items. However, consistent rates ofuntrained framed mands were observed onlywhen the DRF contingency was implementedon the second baseline. Although functionalcontrol over the indirect effects was not


demonstrated with Tom, his data are consistentwith those observed in Ana’s analysis in thatindirect effects of the DRF contingency wereobserved only when two exemplars wereexposed to this condition.

Figure 7 shows rates of single-word andframed mands across the five baselines (music,dinosaurs, bears, puppets, and puzzles) forJason. Although undesirable responses wererecorded for Jason, they are not reported

Figure 6. Independent target responses per minute for Tom during the generalization analysis.


because single-word responses were his pre-dominant mand form (i.e., undesirable re-sponses were not sensitive to the programmedcontingencies). Because the previous analysisindicated that Jason’s predominant mand formwas single words, a DRF contingency was

initially introduced on the music baseline. Aswith Tom, the NCR and DRA data wereobtained from the initial mand analysis. Framedmand models were provided at a rate of 0.3 persession and were eliminated beginning withSession 11. Framed manding immediately

Figure 7. Independent target responses per minute for Jason during the generalization analysis.


increased (M 5 1.7), and single-word mandingdecreased to near zero (M 5 0.6). An importantoutcome was that framed mands occurred in allof the other baselines in which no changes weremade to the contingencies (M 5 1.6 across allbaselines). To determine if the generalizedchange in the complexity of the mand formswas a function of the direct and indirect effectsof the DRF contingency, we returned to theNCR condition and reimplemented the samesequence of conditions. Both single-word andframed manding were reduced to zero or near-zero rates across all five baselines during NCR.The return to DRA resulted once again in animmediate increase in single-word mands for allitems (M 5 1.7). Finally, the DRF conditionwas implemented exclusively on the musicbaseline (0.2 mand model per session), andonce again, framed mands immediately in-creased (M 5 1.8) and single-word mandsdecreased (M 5 0.9). Framed mand modelswere eliminated beginning with Session 26.Although smaller in magnitude relative to theinitial behavior change, the indirect effects ofthe DRF contingency were observed as framedmanding emerged at higher rates in all fourbaselines relative to the previous DRA condi-tion (M 5 0.5). The DRF contingency wasthen arranged on the second baseline (dino-saurs). Framed mand models were provided ata rate of 0.3 per session. Similar indirect effectsof the contingency were observed across theremaining baselines in that framed mandingoccurred at a mean rate of 1.4.

Jason’s results were similar to those observedwith Ana and Tom in that indirect effects of theDRF contingency were observed. However,Jason’s results were also distinct from Ana’sand Tom’s because functional control over thedirect and indirect effects of restricting thecontingency class was demonstrated withina reversal design. Taken together, the resultsof the generalization analysis show that trainingone or two framed mands produced anemergence of untrained framed mands even

when contingencies supported undesirablemand forms. In addition, these results areconsistent with those of Hall and Sundberg(1987) and Sigafoos, Reichle, and Doss (1990),whose data suggested that generalization be-tween tact and mand response classes occurredonly after the development of a minimal tactand mand repertoire.

GENERAL DISCUSSION

Initial analyses were successful in identifyingthe specific response topographies that func-tioned as mands for 3 children. Undesirableresponses were the predominant mand formsfor 2 children, and single-word mands were thepredominant mand form for a 3rd child.Narrowing the contingency class for the 2participants whose predominant mand formwas undesirable resulted in different outcomes.For Ana, the strengthening of one single-wordmand resulted in the strengthening of single-word mands for all toy sets in which no changeswere made to the prevailing contingencies. ForTom, indirect effects of strengthening one ortwo single-word mands were not observed.When the contingency class was narrowed onone or two baselines to framed mands, indirecteffects were seen with all 3 children in thatframed mands emerged on the remainingbaselines in the absence of changes to theprevailing contingencies (i.e., any of the targetmand forms would have resulted in reinforce-ment). Although this phenomenon was ob-served with all 3 children, only Tom’s datasupport the conclusion that generalization ismore likely to occur following the acquisition offramed mands than single-word mands.

These data contribute to the literature onvocal language acquisition in two ways. First,although teaching simpler mands (e.g., singlewords) is common (Gobbi et al., 1986; Win-born et al., 2002; Yoder et al., 1995) and isconsidered to be best practice by some (Horner& Day, 1991; Musselwhite & St. Louis, 1988),


the current data suggest that training one ora few framed mands after single-word mandshave been acquired is likely to result in theemergence of untrained mands (e. g., general-ization). These results are somewhat similar tothose of Stevens-Long (1974), who evaluatedthe influence of differential reinforcement onsimple and compound sentences and found thattraining simple sentences resulted in an increasein simple sentences with no effects on com-pound sentences. Training of compound sen-tences resulted in an increase of compoundsentences and a decrease of simple sentencesand, more important, in the production ofcompound sentences not previously taught.Compound sentences were comprised of twosimple sentences combined with the use of thecarrier word ‘‘and,’’ which possibly serveda similar function as the frame ‘‘I want —,please’’ in the present study.

The results of the current study, althoughpreliminary, suggest that frames should betargeted during mand training following theinitial acquisition of one or two single-wordmands. In addition to replicating and extendingthis relation between single-word and framedmand training, future research may be directedtowards understanding if training frames forother verbal operants (e.g., tacts) results in moregenerative responding.

The second contribution to the literature isthat the current results suggest that the de-velopment of more complex and socially desir-able mand forms may be dependent onextinguishing less complex and less acceptablemand forms. Although single-word mandswould have resulted in reinforcement in theDRA condition, their emergence was dependenton extinguishing undesirable mand forms forAna and Tom. A similar result was obtained forthe relation between single-word and framedmands for all participants. Specifically, theinitial emergence of framed mands was de-pendent on extinguishing single-word mands.Perhaps, more interesting is the fact that

extinction did not need to be comprehensive.The current data suggest that providing extinc-tion on one or a few baselines for less desirablemand forms might result in the emergence ofmore complex mand forms across other non-targeted baselines.

The current results also contribute to theliterature on generalization between the twomost frequently taught functional classes ofverbal behavior, tacts and mands. In previousstudies, which showed that mands and tactswere functionally independent (Hall & Sund-berg, 1987; LaMarre & Holland, 1985;Sigafoos et al., 1989, 1990), the reinforcingvalue of the consequences for mands wasunknown. Similar to Wallace et al. (2006),the data from the present study show that thisindependence may be context specific. The datafrom the present study also suggest thatfunctional independence between mands andtacts is dependent on the contingencies forother functionally equivalent responses and onthe presence or absence of minimal mandrepertoires. That is, although the children wereable to tact the items, more complex mandsemerged only after prompting and differentialreinforcement of a more complex mand and theextinction of less complex mands were pro-grammed. These results also may have differedfrom previous research because the mandeditems in the current study were often highlypreferred items (Wallace et al.). The reinforcingefficacy of the items was suggested by the resultsof the preference assessments but was empiri-cally demonstrated by the control exerted by theitems in the differential reinforcement condi-tion of the mand form analysis.

Teaching one or two mands in the currentstudy resulted in improvement in multiplemand forms, and the conditions in which thispractical outcome occurred were isolated. Inaddition, the results of Jason’s analysis areinteresting on a methodological basis in thatfunctional control over generalization wasachieved. Although generalization is often a goal


or at least an appreciated side effect of mostteaching programs, it is also often the antithesisof functional control and therefore an undesir-able outcome from an experimental perspective.The results of Jason’s analysis show thatgeneralization and functional control can co-exist and suggest an experimental preparation inwhich both can be demonstrated (see Brigham& Sherman, 1968, or Schumaker & Sherman,1970, for alternative preparations for showingfunctional control over generalized perfor-mances).

There are three limitations of the currentstudy that deserve consideration. First, it isquite possible that quicker or more thoroughtransfer would have occurred had we requireda more stringent criterion for the tact repertoiresof our children. All of the children required tacttraining for some of the toy sets, and thecriterion of three consecutive trials of indepen-dent tacting may simply have been too lenient.However, the continued emission of thetopographies of responding (Table 1) whilethe children were engaged with the materials,which occurred throughout both mand analy-ses, suggests that vocal tact repertoires werestrong for these children.

The second limitation pertains to thecontinued availability of reinforcement for thethree mand types across all baselines, whichaffects our ability to comment on the process ofgeneralization. There is evidence of stimulusgeneralization in the current data in that mandframes occurred for the first time underdifferent stimulus conditions that did notinvolve a change in the prevailing context orcontingencies. Response generalization (or in-duction) was apparent in that first instances ofdifferent responses occurred on baselines thatdid not involve a change in the prevailingcontext or contingencies. Clearly, the firstinstances of each response should be consideredinstances of generalization. However, becauseall first instances of each mand type resulted inreinforcement, the continued emission of these

responses was simply a function of reinforce-ment, and therefore should no longer beconsidered evidence for generalization. Futurestudies that evaluate the process of generalizedverbal behavior should consider arrangingextinction or intermittent reinforcement in thebaselines in which the indirect effects of anintervention will be evaluated.

The third limitation is that the use of a free-operant preparation increased the likelihoodthat nonmand responses, which shared similartopographies with our target mands, obscuredour data. An alternative trial-based analysis, inwhich establishing operations and consequencesfor each instance of a response can be bettercontrolled, might lead to more easily interpret-able data regarding functional classes of verbalbehavior. Isolating the conditions under whichother verbal operants, such as echoics, tacts, andintraverbals, emerge and transfer function iswarranted to increase the efficiency of languageprograms based on functional verbal classes.Therefore, the implications of arranging free-operant instead of trial-based conditions shouldbe considered in future research on verbalbehavior.

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Received July 20, 2005Final acceptance September 20, 2006Action Editor, Henry Roane


a preliminary evaluation of the emergence of novel mand forms

Documents

framed mands

preschool children

target mands

understoodas mands

singleword responses

verbal behavior

ential reinforcement

word mandsresult