further examination of factors that … · preference for positive versus negative reinforcement...

FURTHER EXAMINATION OF FACTORS THAT INFLUENCEPREFERENCE FOR POSITIVE VERSUS NEGATIVE REINFORCEMENT

TIFFANY KODAK

LOUISIANA STATE UNIVERSITY

DOROTHEA C. LERMAN

UNIVERSITY OF HOUSTON–CLEAR LAKE

AND

VALERIE M. VOLKERT AND NICOLE TROSCLAIR

LOUISIANA STATE UNIVERSITY

Factors that influence choice between qualitatively different reinforcers (e.g., a food item ora break from work) are important to consider when arranging treatments for problem behavior.Previous findings indicate that children who engage in problem behavior maintained by escapefrom demands may choose a food item over the functional reinforcer during treatment (DeLeon,Neidert, Anders, & Rodriguez-Catter, 2001; Lalli et al., 1999). However, a number of variablesmay influence choice between concurrently available forms of reinforcement. An analogue fortreatment situations in which positive reinforcement for compliance is in direct competition withnegative reinforcement for problem behavior was used in the current study to evaluate severalvariables that may influence choice. Participants were 5 children who had been diagnosed withdevelopmental disabilities and who engaged in problem behavior maintained by escape fromdemands. In the first phase, the effects of task preference and schedule of reinforcement onchoice between a 30-s break and a high-preference food item were evaluated. The food item waspreferred over the break, regardless of the preference level of the task or the reinforcementschedule, for all but 1 participant. In the second phase, the quality of the break was manipulatedby combining escape with toys, attention, or both. Only 1 participant showed preference for theenriched break. In the third phase, choice of a medium- or low-preference food item versus theenriched break was evaluated. Three of 4 participants showed preference for the break over theless preferred food item. Results extend previous research by identifying some of the conditionsunder which individuals who engage in escape-maintained behavior will prefer a food reinforcerover the functional one.

DESCRIPTORS: choice, differential reinforcement, behavioral economics, positive re-inforcement, negative reinforcement, escape-maintained behavior

_______________________________________________________________________________

Variables that influence choice betweenreinforcers, including the schedule, delay, andquality of the reinforcer and the effort requiredto gain access to reinforcement, have beenexamined in a number of studies (e.g., Koehler,Iwata, Roscoe, Rolider, & O’Steen, 2005; Neef,

Shade, & Miller, 1994; Tustin, 1994; Vollmer,Borrero, Lalli, & Daniel, 1999). Research onchoice is important to application becausemultiple reinforcers are often concurrentlyavailable in the natural environment.

Although choice between similar or identicalreinforcers (e.g., two food items) has beenarranged in most research in this area, anincreasing number of applied studies haveexamined choice between qualitatively differentreinforcers (e.g., a break from work or a fooditem; DeLeon et al., 2001; Lalli et al., 1999).Such an arrangement may arise when treatment

This research was based on a dissertation conducted bythe first author in partial fulfillment of the requirementsfor the PhD degree.

Address correspondence to Tiffany Kodak, who is nowat the Munroe-Meyer Institute, UNMC, 985450 Ne-braska Medical Center, Omaha, Nebraska 68198 (e-mail:[email protected]).

doi: 10.1901/jaba.2007.151-05

JOURNAL OF APPLIED BEHAVIOR ANALYSIS 2007, 40, 25–44 NUMBER 1 (SPRING 2007)

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is implemented with less than perfect integrity.For example, the teacher of a child withdevelopmental disabilities may deliver praiseand food reinforcers for completing tasks butpermit escape from the task for disruptivebehavior.

In Lalli et al. (1999), the effects of positiveand negative reinforcement on problem behav-ior and compliance were examined with 5children who engaged in problem behaviormaintained by escape from demands. Treat-ment consisted of providing either negativereinforcement (i.e., a break from the task) orfood for compliance while problem behaviorcontinued to produce escape. Treatment withthe food item was associated with greaterreductions in problem behavior and higherlevels of compliance than treatment with thefunctional reinforcer, even though escape wasavailable for problem behavior. Thus, theparticipants chose the food reinforcer over thefunctional reinforcer when both were concur-rently arranged.

The use of food reinforcers for appropriatebehavior with children who engage in escape-maintained behavior has some advantages overthe use of the functional reinforcer (escape) inclassroom settings. For example, food can bedelivered relatively quickly on rich schedules ofreinforcement while the child continues toengage in academic tasks. Frequent breaks froma task may be impractical to implement andlimit the child’s participation in ongoingclassroom activities. Nonetheless, food reinforc-ers must compete with escape for problembehavior when it is difficult for teachers toimplement escape extinction with integrity.Examining variables that influence preferencefor food reinforcers over escape is important tomaximize the likelihood of compliance withacademic tasks when problem behavior con-tinues to produce the functional reinforcer.

Although results of Lalli et al. (1999)suggested that some children prefer food overescape from demands, a number of variables

may influence choice between these reinforcersduring tasks. DeLeon et al. (2001), for example,examined choice between food and escapeunder increasing schedule requirements witha child who engaged in problem behaviormaintained by escape. The participant wasrequired to complete a number of tasks tochoose between a food item or a break, whileproblem behavior no longer produced escape.The participant chose the food item more oftenthan the break under low schedule require-ments. However, preference switched to thenegative reinforcer when the participant wasrequired to complete 10 tasks before receivingthe opportunity to choose a reinforcer. Theauthors hypothesized that the larger workrequirement functioned as an establishingoperation (EO) by momentarily altering thereinforcing value of the break. However, only 1individual participated in the study. Thus, moreresearch is warranted to evaluate choice betweena break and food under increasing schedulerequirements.

Further research also is needed on factors thatmay interact with the reinforcement schedule toalter choice between reinforcers. For example,in DeLeon et al. (2001), the relative value ofescape versus food under the thin reinforcementschedule may have depended on the preferencelevel of the task. Certain types of tasks may bemore aversive than others, even though multipletasks may be associated with problem behavior.Results of several studies indicate that individ-uals with developmental disabilities will engagein higher levels of problem behavior whenrequired to complete less preferred tasks(Foster-Johnson, Ferro, & Dunlap, 1994;Vaughn & Horner, 1997). For example,Vaughn and Horner compared rates of problembehavior when participants were required tocomplete high- and low-preference tasks. Al-though both tasks produced some problembehavior, the low-preference tasks were associ-ated with much higher rates of problembehavior. Thus, relative to food reinforcement,

26 TIFFANY KODAK et al.

a break from some tasks (more aversive, lesspreferred, or both) may be more valuable thana break from other tasks as the schedulerequirement increases.

The quality of the break and food item in theDeLeon et al. (2001) and Lalli et al. (1999)studies also may have influenced choice betweenreinforcers. In both studies, a highly preferredfood reinforcer was available concurrently witha break alone (i.e., no attention or toys wereavailable during the break). Previous researchhas shown that children with escape-maintainedbehavior may prefer escape to an enrichedenvironment (i.e., a break with toys) over escapealone (Golonka et al., 2000; Zarcone, Fisher, &Piazza, 1996). In Golonka et al., for example,treatment for negatively reinforced problembehavior was more effective when complianceproduced an enriched break rather than a breakalone. Both participants also chose the enrichedbreak more often when the breaks were avail-able concurrently for task compliance. Resultsof Pizza et al. (1997) showed that treatmentwith multiple functional reinforcers (i.e., a breakcombined with tangible items or attention) wasmore effective than treatment with a singlereinforcer (i.e., a break alone) for children whoengaged in multiply controlled problem behav-ior. In the natural environment, a break fromdemands may be combined with access to toysor attention from adults or peers (i.e., a higherquality break). Therefore, further researchshould evaluate whether a more natural, higherquality form of escape alters preference fora food reinforcer over a break.

Alternatively, the quality of the food re-

inforcer may influence choice between reinforc-

ers. In Lalli et al. (1999) and DeLeon et al.

(2001), highly preferred food items were

identified via systematic preference assessments.

These food reinforcers may have been of higher

quality than those typically used in the natural

environment because teachers and parents are

less likely to conduct systematic preference

assessments when selecting food reinforcers.

The extent to which choice between a food item

and a break depends on the preference level of

the food item should be evaluated in further

research.The purpose of this study was to extend

previous research on reinforcer choice (DeLeonet al., 2001; Lalli et al., 1999) by examininghow preference for either a food item or a breakwould be influenced by the schedule require-ments, preference level of the task, andvariations in the quality of the reinforcer. Themethodology was arranged as an analogue oftreatment situations in which both task com-pliance and problem behavior produce re-inforcement. The primary interest of this bridgestudy was on reinforcer choice rather than onthe treatment of problem behavior. In the firstphase, DeLeon et al. was replicated andextended by evaluating choice between foodand escape when reinforcement was deliveredcontingent on compliance to either high-preference or low-preference tasks. In thesecond and third phases, the quality of thebreak and food item was manipulated toexamine how this factor influences choice underrelatively thin schedules of reinforcement.

METHOD

Participants, Settings, and Materials

Five children, aged 4 to 8 years, participatedin the study. Participants had been diagnosedwith developmental disabilities, autism, or bothand had been referred for the treatment ofinappropriate behavior that interfered with taskcompletion. Table 1 displays each participant’sproblem behavior. All of the children werereported to have some visual discriminationskills. Larry, Sam, Mary, and Scott communi-cated vocally using complete sentences andfollowed three-step instructions. Casey hadbeen diagnosed with moderate mental retarda-tion, communicated through gestures or byguiding people towards objects, and followedsome one-step instructions (e.g., ‘‘sit down’’).None of the participants had any sensory or

REINFORCEMENT SCHEDULE AND QUALITY 27

physical deficits except Mary, who had beendiagnosed with visual impairments. Sam begantaking stimulant medication during the thirdphase (i.e., at Session 113). A functionalanalysis was conducted prior to the study toidentify the variables that maintained problembehavior. Only participants whose problembehavior was maintained by escape fromdemands were included in the study.

All assessment and treatment sessions wereconducted in an unused room at the participant’sschool or in therapy rooms at a university-basedearly intervention program for children withautism. The rooms contained a desk and chair,chairs for data collectors, and any relevant sessionmaterials. The therapist and data collectors werepresent during all sessions. Sessions were con-ducted the same time each day with eachparticipant. All sessions were conducted priorto lunch or at least 1 hr after lunch.

Response Measurement and Reliability

Frequency data on reinforcer choice, problembehavior, and compliance were collected vialaptop computers by trained observers duringall assessment and treatment sessions. Reinforc-er choice was defined as pointing to or touchingone of two coupons or items associated with thereinforcer after a verbal prompt. Inappropriatebehavior (see Table 1) included aggression (i.e.,

hitting, pushing, scratching, pinching, andpulling hair), disruption (i.e., throwing materi-als, flopping, crying, and spitting), self-injury(i.e., hand biting, arm biting, and head andbody hitting), and inappropriate vocalizations(i.e., whining, screaming, and saying ‘‘no’’).Compliance was defined as completing a de-mand within 5 s of a verbal or model prompt.

A second independent observer collected dataduring 36% to 54% of sessions for eachparticipant. Interobserver agreement was calcu-lated for reinforcer choice, problem behavior,and compliance by dividing the total number ofoccurrence agreements across consecutive 10-sintervals by the total number of occurrenceagreements plus disagreements and multiplyingby 100%. Mean interobserver agreement forreinforcer choice, problem behavior, and com-pliance across participants was 98% (range,60% to 100%), 94% (range, 50% to 100%),and 99% (range, 90% to 100%), respectively.

General Procedure

Preference assessments. Assessments were con-ducted to identify preference rankings of tangibleitems, food items, and tasks based on proceduresdescribed by Fisher et al. (1992) and Lattimore,Parsons, and Reid (2002). Tangible items, fooditems, and tasks were assessed separately. Highlypreferred tangible items were included in specific

Table 1

Problem Behavior for Each Participant and Preference Assessment Results

Participant Problem behaviorHigh- and

low-preference foods High-preference toysHigh- and

low-preference tasks

Casey Aggression, SIB Ginger cookie and Rice ChexH Bumble ballH anddisco ball

Putting pieces in a puzzle andmatching letters

Larry Aggression, disruption,inappropriatevocalizations

Carob chip and raisin Children’s bookand a video

Receptive identification ofcolored bears andstringing beads

Sam Aggression, disruption Sour cream and onion PringlesHand Gummy BearsH andregular PringlesH and driedapples

Mardi Gras beadsand BumbleBallH

Receptive identification ofanimals and letter puzzle

Mary SIB, inappropriatevocalizations

Fruit snack, apricot (medium-preference food item), andstrawberry juice

Mardi Gras beadsand squishy ball

Stringing beads and shapepuzzle

Scott Aggression, disruption,inappropriatevocalizations

M&MsH and dried apple Light-up snake andplay tools

Peg board and receptiveidentification of opposites


conditions of the functional analysis and inPhases 2 and 3. The highest ranked food itemswere used in certain conditions of the functionalanalysis and during all phases of the study. Thelowest ranked food items were used in Phase 3 (amedium-preference food item also was evaluatedfor Mary in Phase 3). The task preferenceassessment included tasks that were deliveredduring the demand condition of the functionalanalysis. During each trial of the task preferenceassessment, two tasks were placed in front of theparticipant, and the participant was instructed to‘‘pick one.’’ When the participant pointed to ortouched one task, the nonchosen task wasremoved, and the participant was prompted tocomplete three responses from the task that waschosen. For example, if stringing beads wasselected, the participant was required to stringthree beads. Problem behavior was exposed toextinction during preference assessment trials.The task that the participant chose most oftenwas designated the high-preference task; the taskthat was chosen least often was designated thelow-preference task. High- and low-preferencetasks were used in Phase 1. Table 1 displays theresults of the preference assessments conductedwith each participant. Additional preferenceassessments (i.e., multiple stimulus withoutreplacement) were conducted throughout thestudy with various participants (i.e., Sam, Larry,and Scott; see further discussion below) based onprocedures described by DeLeon and Iwata(1996).

Functional analysis. A functional analysis ofproblem behavior was conducted based onprocedures described by Iwata et al. (1994).Functional analysis conditions included attention,demand, toy play, tangible, and no interaction(Casey and Mary only). Sessions (10 min each)were randomly alternated in a multielement de-sign. Additional assessments (i.e., pairwise com-parisons) were conducted with Sam and Scott toclarify functional analysis results. A pairwisecomparison of food and toy play conditions wasconducted with all participants to determine if

access to food was a functional reinforcer forproblem behavior. During the food condition,participants were given presession access toa highly preferred food. Food was removed atthe beginning of the session and returned for 20 scontingent on the target behavior.

Discrimination training. Prior to baseline, theparticipant was taught to discriminate betweentwo coupons (Sam, Scott, and Larry) or twothree-dimensional items (Mary and Casey) andto touch the coupons or items to obtain thedesignated reinforcer. Coupons were used forparticipants whose teachers reported that theycould discriminate among different pictures.Items were used for participants who did notreportedly possess such discrimination skills. Ifthree-dimensional items were used, one itemrepresented the break (e.g., a timer) and theother item represented the food (e.g., a bag offood). During discrimination training, thetherapist physically guided the participant tochoose one coupon or item and delivered theconsequence associated with the coupon or item(i.e., either a 30-s break from discriminationtraining or a small piece of food). Afterphysically guiding the participant to pick eachcoupon or item a minimum of five times, thetherapist required the participant to complywith one instruction (e.g., string one bead) andthen permitted the participant to choosebetween the two coupons or items. Thisprocedure was conducted a minimum of threetimes. The therapist then asked the child topoint to or say the coupon or item associatedwith either a break or food item. If the childcould accurately perform this activity twice foreach coupon or item, discrimination trainingwas completed. If the participant did notaccurately discriminate between the coupons,discrimination training was conducted withitems in place of the coupons, and trainingcontinued until the criteria above were met.Following discrimination training, probes wereconducted daily prior to sessions to ensure thatthe participant’s choice remained under dis-


criminative control of the two coupons oritems. During daily probes, the therapist forceda choice for each coupon or item once andrepeated the last step of discrimination training.

Experimental Design

High-preference and low-preference taskswere alternated in a multielement design duringPhase 1. The effects of the schedule onreinforcer choice also were evaluated in a reversaldesign in Phase 1. During Phase 2, theparameters of the break were manipulated usinga reversal design. In Phase 3, the effects ofreinforcer quality on choice were evaluatedusing a reversal design.

PHASE 1

Procedure

The purpose of Phase 1 was to evaluatepreference for reinforcers under increasingschedule requirements with high- versus low-preference tasks. High- and low-preference taskswere alternated in a multielement design.During all sessions, the experimenter presentedinstructional trials using a graduated three-stepprompting procedure (verbal, model, physicalprompts). No programmed consequences wereprovided for problem behavior (i.e., problembehavior was exposed to extinction).

Baseline (no reinforcement). Sessions with themost and least preferred tasks were conducteda minimum of five times each. No programmedconsequences were provided for compliance.Five trials were conducted during each session.The purpose of baseline was to evaluate levels ofcompliance and problem behavior in the absenceof reinforcement for appropriate behavior.

Reinforcer choice. All procedures were thesame as in baseline, but reinforcement wasprovided for task compliance. The participanthad the opportunity to choose between tworeinforcers contingent on compliance followinga verbal or model prompt. The number of timesthe participant was required to complete thetask to gain access to reinforcement wasgradually increased on a fixed-ratio (FR)

schedule beginning with FR 1. Each sessionended when the participant had received fiveopportunities to choose between reinforcers.

When the participant had complied with therequired number of demands (depending on theschedule), the therapist placed both coupons oritems on the table at equal distances from theparticipant. The therapist said, ‘‘pick one.’’ Ifthe participant chose the snack coupon or item,the participant was given a small piece ofa highly preferred food. The next demandbegan immediately after delivery of the fooditem so that the positive reinforcer was notconfounded with a break from the task. If theparticipant chose the break coupon or item, thetherapist turned away from the participant andprovided a 30-s break from task demands. Allparticipants chose a coupon or item within 5 sof the initial verbal prompt to pick one.

When reinforcer choice remained stable forat least three sessions under FR 1, the schedulewas increased to FR 2. Reinforcer choice wasconsidered stable if it varied by 20% or lessfrom one session to the next. The schedulecontinued to be increased (FR 2, FR 5, FR 10,FR 20, FR 40) if choice remained stable for atleast three consecutive sessions under eachschedule value until preference appeared tochange (e.g., switched from the food item to thebreak) or until the schedule reached FR 40. Ifpreference changed at or before the schedulereached FR 40, FR 2 and the highest schedulerequirement for that participant was replicated.

PHASE 2

Procedure

All of the children participated in Phase 2because results of Phase 1 indicated a preferencefor the food item under relatively thin re-inforcement schedules (e.g., FR 20 or FR 40).The purpose of Phase 2 was to examine howpreference would change if the break containedaccess to other positive reinforcers. Because theparameters of the break were manipulated, theconditions most likely to increase the value of the


break were in effect during this phase. Thus, thelow-preference task and the thinnest scheduleunder which the food reinforcer was consistentlypreferred over the break were used. All otherprocedures were identical to those in Phase 1.

Baseline. Data from the last phase in Phase 1(i.e., when the highest schedule requirementreached by the participant was replicated) servedas the baseline data for Phase 2, with twoexceptions. First, an additional baseline wasconducted with Sam when a change in settingoccurred following Phase 1. The baseline forPhase 2 was conducted in the new setting.Second, a relatively rich schedule (FR 5) waschosen as the baseline schedule for Scottbecause reinforcer choice in Phase 1 wassomewhat variable even under rich schedulesof reinforcement (e.g., the replication of FR 2).Thus, a baseline phase with this schedule wasimplemented during Phase 2.

Reinforcer choice. Highly preferred tangibleitems (i.e., toys), therapist attention, or bothwere systematically combined with the break.When the break was selected, the therapistremoved the task materials, provided the twomost highly preferred toys, or delivered atten-tion (i.e., conversation) for 30 s. The separateeffects of attention and tangible items duringthe break were evaluated for 1 participant toidentify the particular variables (attention,tangible items, or both) that were responsiblefor the change in preference. This evaluationwas followed by a reversal to the break only(i.e., baseline) and replication of the break plusthe relevant variable (attention).

PHASE 3

ProcedureFour of the 5 children (Sam, Scott, Casey,

and Mary) participated in Phase 3 because theycontinued to show preference for the food itemover the enriched break in Phase 2. The purposewas to examine how preference would change ifthe quality of the food item was manipulated.

Baseline. Data from the last phase in Phase 2(when the participant could choose between the

high-preference food item and the enrichedbreak) served as the baseline data for Phase 3,with the exception of Mary, who was the first toparticipate in Phase 3. We hypothesized thata lower preference food item would lead toa complete switch in preference to the enrichedbreak even when a denser schedule of re-inforcement was in place (e.g., FR 10).Therefore, we began Phase 3 under the FR 10schedule with Mary only. When her preferencedid not change, the same reinforcementschedules that had been implemented in Phase2 were used for the remaining participants.

Reinforcer choice. Participants could choosebetween a low-preference food item or anenriched break (i.e., a break with access to twohighly preferred toys and adult attention). Amedium-preference food item (i.e., food itemranked in the middle of the items in the foodpreference assessment) also was evaluated withMary only. If participants chose the enrichedbreak more often than in baseline, a reversal tothe high-preference food item was implemen-ted. Following the reversal, the low-preferencefood item was reinstated to replicate the changein preference.

The procedures conducted in Phase 3 weremodified for Sam after a change in preferencefrom the low-preference food to the break wasnot replicated (i.e., Sam chose the low-preference food over the break). An additionalpreference assessment was conducted to iden-tify a food item that was less preferred thanthe current food item. The least preferred fooditem that Sam would consume was evaluatedas the second low-preference food item. Wealso hypothesized that the enriched break mayhave acquired some aversive properties duringthe course of the study (e.g., Sam began topush the toys away and wouldn’t talk with thetherapist during the break). Therefore, choicebetween the food items and a nonenrichedbreak (i.e., a 30-s break with no toys andattention) was evaluated at the end of thephase.


RESULTS

Functional Analysis

Results of the functional analysis and pair-wise comparisons are presented in Figure 1.Casey’s functional analysis suggested that prob-lem behavior was maintained by negativereinforcement in the form of escape fromdemands. Initially, rates of problem behaviorwere highest in the play and demand condi-tions. However, results were more clearlydifferentiated during the last 14 sessions of theassessment, with the highest rates of problembehavior occurring during the demand condi-tion. During the pairwise comparison of foodand toy play conditions, higher rates of problembehavior occurred in the toy play conditionthan in the food condition, suggesting that thebehavior was not maintained by access to food.Nonetheless, food cannot be excluded asa possible maintaining reinforcer because prob-lem behavior was observed in the foodcondition and no food was provided in thetoy play condition. Larry exhibited the highestrates of problem behavior during the tangibleand demand conditions of the functionalanalysis, suggesting that his problem behaviorwas maintained by access to tangible items andescape from demands. Results of the pairwisecomparison of food and toy play conditionsindicated that problem behavior was notmaintained by access to food items. Sam’sresults suggested that his problem behavior wasmaintained by adult attention and escape fromdemands. However, the rate of problembehavior began to increase during the last twosessions of the tangible condition, so a pairwisecomparison of the tangible and toy playconditions then was conducted. Results in-dicated that problem behavior was also main-tained by access to toys. The pairwise compar-ison of toy play and food conditions suggestedthat problem behavior was not maintained byaccess to food items. Results of Mary’smultielement functional analysis and the pair-wise comparison of food and toy play condi-

tions indicated that problem behavior wasmaintained by escape from demands and notby access to food items. In the first phase ofScott’s functional analysis, the highest rates ofproblem behavior occurred in the tangiblecondition, suggesting that problem behaviorwas maintained by access to toys. Problembehavior was also somewhat elevated during theattention condition, increasing to high levelsduring the final attention session. Due to thenature of the problem behavior during thissession (i.e., severe aggression), additionalattention sessions were not conducted. Becauseparent reports and previous observations in theclassroom suggested that problem behavior mayhave been maintained by escape from demands,additional sessions with demand and toy playconditions were conducted to further evaluatethis potential function. Results of the pairwisecomparisons suggested that problem behaviorwas sensitive to negative reinforcement andaccess to food items.

Phases 1, 2, and 3

The primary dependent variable was re-inforcer choice, which is depicted in Figures 2through 6. Due to the lengthy nature of theevaluation, data from Phase 1 are graphedseparately from the data collected during Phases2 and 3 for each participant. However, datafrom Phase 1 that served as the initial baselinecondition for Phase 2 are reproduced in thesecond graph for some participants. Results forthe two secondary dependent variables (i.e.,problem behavior and compliance) are brieflysummarized below (session data are available bycontacting the first author).

Choice. Overall, Casey showed a strongpreference for the food over the break duringPhase 1, even under the highest schedulerequirement (Figure 2). Although respondingwas variable under his first exposure to FR 40,Casey showed a clear preference for the fooditem when FR 40 was replicated. Choicebetween reinforcers was similar across the high-and low-preference tasks. When attention and


Figure 1. Responses per minute of problem behavior across conditions of the multielement functional analyses and

pairwise comparisons for Casey, Larry, Sam, Mary, and Scott.


Figure 2. Percentage of trials in which Casey chose the food versus the break across increasing schedule requirementsin Phase 1 (top); low 5 low-preference task; high 5 high-preference task. Percentage of trials in which Casey chose either

the high-preference food or the low-preference food versus the break during Phases 2 and 3 (bottom). EB 5 enrichedbreak (break with tangible items and attention).


Figure 3. Percentage of trials in which Larry chose the food versus the break across increasing schedule requirementsin Phase 1 (top); low 5 low-preference task; high 5 high-preference task. Percentage of trials in which Larry chose either

the high-preference food or the enriched break (EB) during Phase 2 (bottom).


Figure 4. Percentage of trials in which Sam chose the food versus the break across increasing schedule requirementsin Phase 1 (top); low 5 low-preference task; high 5 high-preference task. Percentage of trials in which Sam chose eitherthe high-preference food or the low-preference food versus the break during Phases 2 and 3 (bottom). EB 5 enriched

break (break with tangible items and attention); Lo P F 2 5 second low-preference food item.


Figure 5. Percentage of trials in which Mary chose the food versus the break across increasing schedule requirements

in Phase 1 (top); low 5 low-preference task; high 5 high-preference task. Percentage of trials in which Mary chose eitherthe high-preference food, medium-preference food, or the low-preference food versus the break during Phases 2 and 3(bottom). EB 5 enriched break (break with tangible items and attention); med 5 medium-preference food item; low 5

low-preference food item.


Figure 6. Percentage of trials in which Scott chose the food versus the break across increasing schedule requirementsin Phase 1 (top); low 5 low-preference task; high 5 high-preference task. Percentage of trials in which Scott chose eitherthe high-preference food or the low-preference food versus the break during Phases 2 and 3 (bottom). EB 5 enriched

break (break with tangible items and attention).


highly preferred toys were added to the breakduring Phase 2 (i.e., the enriched break), hecontinued to show preference for the food item(Figure 2). Therefore, it was unnecessary toevaluate the individual components of theenriched break. In Phase 3, Casey showeda preference for the break when the lowerpreference food and either an enriched break ora nonenriched break (last condition) wereavailable concurrently.

Results for Larry also indicated a clearpreference for the food item over the breakunder all schedules of reinforcement in Phase 1(Figure 3). The break was chosen more oftenduring the low-preference task under the FR 20schedule. However, choice responding wassimilar for both tasks under the FR 40 schedule.During Phase 2, Larry preferred the food itemto the break unless attention was deliveredduring the break (Figure 3).

Sam showed a preference for the food itemover the break, regardless of the preference levelof the task, until the schedule reached FR 20 inPhase 1 (Figure 4). Under the initial FR 20schedule, preference was variable and unstable;however, he showed a clear preference for thefood item to the break when the FR 20 schedulewas reintroduced. In fact, preference for thefood item was maintained even when theschedule was increased to FR 40. Althoughchoice was fairly similar across both tasks, Samwas more likely to choose the break over thefood when working on the low-preference taskunder FR 20 and FR 40. Sam’s choices for thefood versus the break under FR 40 weresomewhat more variable when this conditionwas conducted in a new setting as the baselinefor Phase 2 (Figure 4). However, he showeda consistent preference for the food item whenhe could choose between the food and anenriched break. When the first low-preferencefood item was introduced (i.e., ranch-flavoredPringlesH) during Phase 3, preference was morevariable than it had been during baseline,although he continued to show preference for

the food item. When the second low-preferencefood item (i.e., dried apple) was introduced,preference became more variable. Sam chose theenriched break more than the food item duringsome of the sessions. However, he chose thefood over the enriched break when the secondlow-preference food was reintroduced.

Anecdotal observations suggested that theenriched break may have acquired some aversiveproperties for Sam. He began to push the toysaway and would not talk with the therapistduring the break. Choice between the low-preference food item and a nonenriched breakwas conducted to evaluate this hypothesis. Samimmediately showed a change in preferencefrom the food to the nonenriched break, andthese results were replicated. In the last panel ofPhase 3, Sam did not show a consistentpreference for either the high-preference foodor the nonenriched break until the last fewsessions, during which he chose the foodsomewhat more than the break.

Mary consistently showed a clear preferencefor the food item over the break, regardless ofthe reinforcement schedule or preference levelof the task in Phase 1 (Figure 5). Preference forthe food persisted even when the enriched breakwas introduced and the schedule was increasedfrom FR 20 to FR 40 in Phase 2 (Figure 5).When she could choose between a low- ormedium-preference food and the enrichedbreak under FR 10 in Phase 3, she initiallybegan to choose the break over the food onsome trials. However, exclusive preference forthe food returned after the fifth session and wasmaintained throughout the rest of the phase,despite an increase in the schedule to FR 40.

During Phase 1, Scott’s preference for thefood over the break was initially somewhatvariable, but he consistently chose the foodmore often than the break as the schedule wasincreased to FR 20 (Figure 6). Preferencebecame highly variable when the schedule wasincreased to FR 40. Although Scott chose thefood item more than the break in the majority


of sessions, he showed exclusive preference forthe break during some of the sessions, and theseresults were replicated. Results were similaracross low- and high-preference tasks. Arelatively rich schedule (FR 5) was chosen asthe baseline schedule for Phase 2 becausepreference was somewhat variable even underrich schedules of reinforcement (e.g., thereplication of FR 2). Scott showed a preferencefor the food over the nonenriched break duringbaseline. When the enriched break was in-troduced, he continued to show preference forthe food even when the schedule was increasedto FR 10 and FR 20. When the low-preferencefood item was first introduced during Phase 3,preference switched from the food to theenriched break. However, Scott’s choices werehighly variable during the replication phase. Heshowed exclusive preference for the break insome sessions, although he chose the food itemmore than the break in the majority of sessions.This variability was not observed when thehigh-preference food was reintroduced in thefinal phase, during which he showed exclusivepreference for the food.

Problem behavior and compliance. For allparticipants, compliance remained relativelyhigh throughout all phases of the study. Fourparticipants engaged in very little problembehavior after an initial decrease in respondingduring Phase 1. Casey exhibited higher rates ofproblem behavior under thinner schedules ofreinforcement during all phases even thoughbehavior was on extinction. Rates of problembehavior were near zero under the richschedules of reinforcement but increased underthe FR 40 schedule in each phase. Rates ofproblem behavior were slightly higher duringlow-preference tasks for Larry, Sam, and Scott.

DISCUSSION

Of 5 children with autism who displayedproblem behavior that was maintained byescape from demands, all but 1 (Scott) showeda clear preference for food over a brief break

from tasks, regardless of the reinforcementschedule. Scott, Mary, Casey, and Sam showedpreference for the food item even whenattention and tangible items were availableduring the break. Larry displayed a change inpreference when attention was available duringthe break. Of the 4 children who participated inPhase 3, 3 (Sam, Casey, and Scott) showeda change in preference when the quality of thefood item was manipulated. However, Marycontinued to choose the medium- and low-preference food over the break, despite increasesin the schedule to FR 20 and FR 40. Together,these results extend previous research by furtherevaluating the conditions under which individ-uals who engage in escape-maintained behaviorprefer a food reinforcer over a functional one.

The present investigation was arranged as ananalogue of treatment situations in whichpositive reinforcement for appropriate behavioris in direct competition with negative reinforce-ment for problem behavior. Nonetheless, therelative potency of food as a reinforcer in thisstudy and in previous research (DeLeon et al.,2001; Lalli et al., 1999) has a number ofimplications for the use of reinforcement as partof treatment for escape-maintained behavior.Results suggest that teachers and parents shouldconsider using highly preferred positive re-inforcers when it is difficult or inconvenientto deliver the functional reinforcer (escape) forappropriate behavior or to withhold escapecontingent on problem behavior (e.g., theperson is too large to guide physically). Pro-viding preferred food reinforcers contingent oncompliance may effectively increase compliance,even if problem behavior continues to produceaccess to a break. However, food items chosenrandomly rather than via systematic preferenceassessments may not effectively compete withescape-maintained behavior. Results also sug-gest the importance of assessing preference forpositive versus negative reinforcement underdifferent conditions. Preference for highly pre-ferred food reinforcers may be influenced by


additional variables such as the effort requiredto gain access to the food item or delays toreinforcement. Future research should evaluatehow additional parameters of reinforcementinfluence the effectiveness of food reinforcersduring treatment of escape-maintained behav-ior.

These findings add to the literature onreinforcer choice and preference in several ways.First, previous studies comparing choice be-tween positive and negative reinforcement didnot specifically assess or manipulate the prefer-ence level of the task, an important EO fornegative reinforcement (DeLeon et al., 2001).Results from the current investigation suggestthat the preference level of the task may notnecessarily affect preference for food overa break. It should be noted that all tasksincluded in the assessment were those that hadoccasioned problem behavior during the func-tional analysis. Thus, the relevant EO shouldhave been in effect. However, extinction forproblem behavior may have masked differencesin choice during high- and low-preference tasks.Alternatively, food may have been such a potentreinforcer that the participants preferred thefood reinforcer over the functional reinforcer,regardless of the EO for the break. Anotherpossible explanation is that the EOs associatedwith the two tasks were fairly similar. High- andlow-preference tasks were identified via a taskchoice assessment. A better method for identi-fying variations in task preference would havebeen to evaluate the amount of problembehavior and compliance associated with eachtask. In a relevant study, Vaughn and Horner(1997) evaluated rates of problem behaviorduring high- and low-preference tasks withindividuals with severe disabilities. Higher ratesof problem behavior were observed whenstudents were required to complete less pre-ferred tasks. In addition, the high-preferencetasks were consistently chosen over the low-preference tasks when students were permittedto choose between tasks.

Second, the present investigation evaluatedchoice between a food reinforcer and multiplefunctional reinforcers. In previous investigations(DeLeon et al., 2001; Lalli et al., 1999),participants could choose between a food itemand a break alone, although some children mayprefer escape to an enriched environment overescape alone (Golonka et al., 2000; Piazza et al.,1997). Furthermore, it is unlikely that attentionor toys would be unavailable during workbreaks in the natural environment. (Theparticipants in the present investigation wereallowed to play with toys during breaks in theirclassroom setting.) Therefore, evaluating pref-erence for food versus a break alone may havelimited the generality of previous researchfindings. Although the problem behavior of 3children (Sam, Scott, and Larry) was main-tained by attention or tangible items in additionto escape from demands, only Larry shiftedpreference from the food reinforcer to the breakwhen attention and tangible items were addedto the break during Phase 2. Interestingly, Larrypreferred the break when attention was de-livered during the break, even though results ofhis functional analysis indicated that problembehavior was maintained by tangible items butnot by attention. One possible explanation forthis finding is that the type of attentionmanipulated in the functional analysis (repri-mands) did not function as a reinforcer, unlikeother forms of attention (e.g., physical atten-tion, praise).

Results of Phase 3 for Sam indicated thatattention may have become aversive because hechose the low-preference food item over thebreak only when the break was enriched withtoys and attention. Adult attention may havebecome aversive over the course of the studybecause it was repeatedly paired with demands.It is also possible that Sam became satiated byattention, because attention was deliveredcontinuously in the form of demands prior tothe break, with praise and conversation de-livered during the break. Results for 1 partic-


ipant in a study by Vollmer and Iwata (1991)suggested that attention switched from a reinfor-cing stimulus to an aversive stimulus after theindividual was repeatedly exposed to 15 min ofpresession attention. The participant beganrunning away from the therapist and threw itemsat the therapist who was attempting to deliverattention. However, another possible explanationis that Sam began receiving stimulant medicationduring this phase. Previous research suggests thatstimulant medication may function as an abolish-ing operation for attention-maintained problembehavior (Northup et al., 1999). Thus, theprovision of stimulant medication during Phase3 may have decreased the value of attention ortangible items, resulting in Sam’s preference forthe food over the enriched break.

Third, the present investigation adds to theliterature by replicating DeLeon et al. (2001)with multiple participants. For the 1 participantin the DeLeon et al. study, preference for foodswitched to the break under thin schedules ofreinforcement (i.e., FR 10), although this resultwas not replicated within subject. In the presentinvestigation, choice was somewhat more vari-able under the thinner reinforcement schedulesfor 3 participants in Phase 1 (Sam, Casey, andScott); however, all participants usually pre-ferred the food to the break when a potent fooditem was identified via a systematic preferenceassessment and the break was not combinedwith other positive reinforcers. In addition, theincreased variability in choice under the thinnerschedules was not replicated within subject forCasey and Sam, a finding reported by DeLeonet al. It is possible that the EO for the breakdecreased as a result of repeated exposure to thetask under thin reinforcement schedules. Thatis, the task may have become less aversive afterthe participant had been exposed to numerousinstructional trials (e.g., Smith, Iwata, Goh, &Shore, 1995). If so, a break from the task mayhave become less valuable, decreasing thelikelihood that the participant would choosethe break over the food.

Results of the study also can be understoodby considering some concepts drawn frombehavioral economics, specifically the degreeof demand elasticity for the reinforcers and thetype of economy. Demand elasticity is de-termined by changes in consumption of a re-inforcer as the price of the reinforcer ismanipulated. Demand is considered relativelyelastic if consumption of the reinforcer is readilyinfluenced by changes in the price of thereinforcer (e.g., increases or decreases in theschedule). The nature of the commodity(essential or nonessential) is one variable thatcan influence demand elasticity (Hursh, 1984).Essential commodities, such as food, usuallyhave few substitutes. Toys and breaks fromwork are probably nonessential commodities. Inthe present study, participants may havecontinued to prefer the food item under thinschedules of reinforcement, even when otherreinforcers were added to the break, because thefood item was an essential commodity. Thetype of economy (open or closed) also mayinfluence responding during choice situations.Individuals may not engage in a response at thesame rate in experimental sessions if thecommodity is available independent of respond-ing outside the session (an open economy)rather than if the commodity is available onlyfor responding during the session (a closedeconomy; Hursh, 1978). The participants in thepresent study typically had access to numerousbreaks outside the experimental sessions, in-cluding a break immediately prior to andimmediately following the sessions. This ap-proximation of an open economy may accountfor the relative elasticity of escape. Althoughfood also was available outside the sessions,participants may not have had access to thespecific food items that were used as reinforcers.

One limitation of the study was the failure todemonstrate experimental control over choiceresponding with most of the participants inPhase 1, with all but 1 participant in Phase 2,and with Mary in Phase 3. For these partici-


pants, choice was not highly or consistentlysensitive to the variables that were manipulatedin these phases, an outcome that was notanticipated due to previous research on thesefactors. A multiple baseline across participantsdesign could be implemented in future studiesto demonstrate experimental control duringmanipulations of the schedule value. In theevent that choice responding is not sensitive tomanipulations of the independent variable,choice between the currently preferred reinforc-er and no reinforcement could be implementedto demonstrate experimental control.

Several of the findings were not replicatedwithin subject in Phase 1, as noted previously.In addition, an apparent change in preferencefrom the food to the break was not replicatedfor Scott in Phase 3. These failures to replicatemay indicate that uncontrolled variables influ-enced the results. In fact, these results and thoseof DeLeon et al. (2001) suggest that choicebetween food and breaks may be influenced byadditional variables that were beyond the scopeof the present study (e.g., recent history withcertain schedules, decreased aversiveness of thetask). Future research should investigate whypreference for reinforcers under increasingschedule requirements may fluctuate over time.

An additional limitation was that partici-pants were able to escape the analogueinstructional context earlier by choosing thefood item over the break because sessionduration was trial based. Thus, the partici-pants’ choice behavior may have reflecteda greater sensitivity to molar escape contin-gencies (the total session duration) than to theimmediate (molecular) contingencies. In addi-tion, the schedule of reinforcement was notthinned past FR 40. Due to the participants’schedules, daily sessions were limited to 1-hrtime blocks. One session under the FR 40schedule required approximately 45 min tocomplete for most participants. Thus, thinnerschedules likely would have required pro-hibitive session lengths. A final limitation was

that food appeared to be a functional re-inforcer for Scott’s problem behavior andcould not be excluded as a maintaining re-inforcer for Casey’s behavior. Nevertheless, theresults for Casey and Scott were similar tothose for the other participants.

Results of the present investigation haveseveral implications for future research. Moreresearch is needed to identify factors that mayinfluence preference for competing reinforcers.One possible area of future research involvesevaluating other aspects of escape from de-mands. For example, lengthier breaks may bemore likely to compete with food reinforcers asthe work requirements increase. Additionalresearch on economic variables (i.e., open andclosed economies, increasing unit price) couldbe conducted to evaluate the factors thatinfluence choice. For example, food reinforcersevaluated within session could be availablefollowing experimental sessions to determinewhether choice between a food item and a breakwould be influenced by postsession reinforce-ment. Comparing choices when reinforcers areimmediate versus delayed would be anotherimportant area of research. For example,children who show a preference for immediatefood over an immediate break could be givena choice of two different tokens while complet-ing the schedule requirements of a task. Onetoken would be exchangeable for food and theother would be exchangeable for a breakfollowing the completion of the task. Wouldpreference change when reinforcers are delayedunder the token economy? Variables that maybe responsible for fluctuations in preferenceover time (e.g., repeated exposure to increasingschedule requirements; gradual increases in theschedule) also should be evaluated.

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Received October 17, 2005Final acceptance September 18, 2006Action Editor, Iser DeLeon


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