JOURNAL OF APPLIED BEHAVIOR ANALYSIS 2014, 47, 314–324 NUMBER 2 (SUMMER) A LABORATORY COMPARISON OF TWO VARIATIONS OF DIFFERENTIAL-REINFORCEMENT-OF-LOW-RATE PROCEDURES JOSHUA JESSEL AND JOHN C. BORRERO UNIVERSITY OF MARYLAND, BALTIMORE COUNTY We compared 2 variations of differential-reinforcement-of-low-rate (DRL) procedures: spacedresponding DRL, in which a reinforcer was delivered contingent on each response if a specified interval had passed since the last response, and full-session DRL, in which a reinforcer was presented at the end of an interval if the response rate was below criterion within the specified interval. We used a human-operant procedure and analyzed within-session responding to assess any similarities or differences between procedures. Data revealed a positive contingency between responding and reinforcement under the spaced-responding DRL schedule and a negative contingency under the full-session DRL schedule. Furthermore, 60% of the participants discontinued responding by the last full-session DRL session. Implications for the appropriate procedural and taxonomical usage of both DRL schedules are discussed. Key words: differential reinforcement of low rates, differential reinforcement of other behavior, human operant, interresponse time, translational research Differential-reinforcement-of-low-rate (DRL) schedules are temporally based reinforcement schedules that arrange the delivery of reinforcers contingent on reduced rates of responding (Ferster & Skinner, 1957). Two commonly conducted iterations of DRL schedules differ based on the unit of analysis; one programs a contingent relation between each response, whereas the other programs a contingent relation between an overall count within a particular time frame that can be intervals, sessions, or days (Deitz & Repp, 1973). In the first DRL variation, a response produces a reinforcer only after a specified time of no This study was conducted in partial fulfillment of the requirements for the master’s degree of the first author at the University of Maryland, Baltimore County. We thank Iser G. DeLeon and SungWoo Kahng for their insightful contributions to earlier versions of this manuscript. Joshua Jessel is now affiliated with Western New England University. Preparation of this article was supported by Grant RO1HD049753 from the Eunice K. Shriver National Institute of Child Health and Human Development (NICHD). Its contents are solely the responsibility of the authors and do not represent the official views of NICHD. Address correspondence to J. C. Borrero, Department of Psychology, University of Maryland, Baltimore County, 1000 Hilltop Road, Baltimore, Maryland 21250 (e-mail: jborrero@umbc.edu). doi: 10.1002/jaba.114 responding has elapsed (Catania, 2013). The interval between each response is known as the interresponse time (IRT), and this schedule is sometimes called an IRT > t arrangement because the time between responses (IRT) must be greater than the programmed interval (t) to produce a reinforcer. These temporally sensitive schedules result in the subsequent reinforcement of both the relative IRT and response, respectively, characterizing patterns of behavior that are referred to as spaced responding. This schedule has been aptly named a spaced-responding DRL in the applied literature (Deitz, 1977). The second DRL variation defines a contingency between responding and a reinforcer following the elapse of a predetermined interval as long as the overall rate within that interval is below a predetermined criterion (Catania, 2013). In some cases, the absence of responding is considered an acceptable dimension, and the characteristic features of maintaining low rates during the DRL schedule are ignored (e.g., Bird, Hepburn, Rhodes, & Moniz, 1991; Hagopian, Kuhn, & Strother, 2009; Shaw & Simms, 2009; Turner, Green, & Braunling-McMorrow, 1990). For example, Deitz and Repp (1973) specifically termed this variation a full-session DRL and arranged criteria whereby reinforcers were presented, not 314 VARIATIONS OF DIFFERENTIAL REINFORCEMENT contingent on a response, but at the end of the interval if the target behavior (i.e., talking out during class without permission) occurred at a rate less than a specified criterion. This procedure inherently permitted reinforcer delivery given no responding. Because zero responding is sufficient to produce reinforcer delivery, Deitz and Repp’s example of a full-session DRL may have more in common with a differential-reinforcement-of-otherbehavior (DRO) schedule in that (a) reinforcers are presented on an interval basis, (b) there is only an indirect relation between reinforcer deliveries and IRTs, and (c) there is a possible negative contingency between reinforcer presentation and the target response. The combined schedule could instead be described as an alternative DRO DRL schedule (Ferster & Skinner, 1957). This description incorporates the two alternative contingencies available for contacting reinforcement, in that the organism can either not respond at all or respond x or fewer times. To draw attention to this detail may seem trivial, but the effects on behavior could be as substantial. Specifically, the schedule arrangement supports both low-rate and zero responding. Therefore, the spaced-responding DRL and full-session DRL might establish disparate patterns of responding and might be properly used in different contexts. Of these two methods of programming DRL schedules, the majority of basic research has been conducted using spaced-responding DRL schedules that maintain responding. However, in application, the spaced-responding DRL is used infrequently and is supplanted by the full-session DRL that might actually be more likely to eliminate responding. In other words, basic and applied research that involves DRL arrangements has focused on different contingencies that may promote very different response patterns. The explanation for this difference may be elucidated when considering why applied researchers would select a DRL arrangement as a means of clinical intervention. Spaced-responding DRL schedules have often been implemented to reduce response forms that 315 are acceptable or valued, but only when the responses occur at a low to moderate rate. These include responses such as hand raising in classroom settings (Austin & Bevan, 2011) and independent eating or drinking during mealtimes (Anglesea, Hoch, & Taylor, 2008; Lennox, Miltenberger, & Donnelly, 1987; Wright & Vollmer, 2002). Thus, the goal is to reduce the frequency of the target response but not to completely extinguish responding. The spacedresponding DRL schedule lends itself to cases for which high rates of the target behavior could be hazardous (e.g., rapid eating could lead to an increased chance of choking) but complete elimination of the response would alternatively lead to dangerous complications (e.g., starvation). In contrast, full-session DRL schedules, or the alternative DRL DRO schedules, have been implemented in cases in which the target behavior is inappropriate and reduced rates are acceptable but complete elimination is ideal. Common examples of these behaviors include talking out during class without permission (Deitz & Repp, 1973) or engaging in stereotypy (Singh, Dawson, & Manning, 1981). The DRL component accounts for the permissible (tolerable) rate of inappropriate behavior to occur, whereas the alternative DRO component schedules reinforcement during intervals of no responding. Austin and Bevan (2011) used an amalgamation of procedures from both the spacedresponding and full-session DRL schedules to decrease requests for help by three typically developing elementary school students. The authors reported considerable decreases in requests during the treatment component. However, some features of the results warrant consideration. Although the ability to eliminate the target response completely has often been regarded as a strength of the DRO schedule, the target response (requests for help) selected for this study would likely not fall under that category. The full-session DRL schedule has often been preferred over the spaced-responding DRL schedule because of the relative simplicity of 316 JOSHUA JESSEL and JOHN C. BORRERO the nonresetting interval for teachers in classroom settings (Deitz, 1977; Deitz & Repp, 1973); however, this may not be clinically appropriate when considering the possibility of extinguishing an appropriate classroom response. The purpose of the current study was to compare the effects of the spaced-responding DRL schedule and the full-session DRL schedule in a preliminary human-operant investigation using college students as participants. A DRObased schedule was specifically targeted because of the frequency with which DRO procedures are represented in the research literature related to reducing problem behavior (Kahng, Iwata, & Lewin, 2002). The study was designed to provide laboratory (translational) evidence for possible similarities or differences between the underlying mechanisms of the procedures and whether or not the change in a procedural taxonomy is warranted. That is, if the full-session DRL schedule results in maintained responding similar to that of the spaced-responding DRL, then there would be little evidence to suggest change, because the implications for application will not differ for practitioners and applied researchers. METHOD Participants Sixteen university students (seven women, nine men), with an age range of 18 to 29 years old, were recruited for participation. All participants were sufficiently proficient in the manipulation of a computer mouse and had experience using computers. Three participants served as pilots during the initial stages of program development. Two of the remaining 13 participants engaged in similar response rates during the variable-ratio (VR) and extinction conditions, and one participant refused to wear the headphones and could not hear when points were being delivered. Therefore, 10 data sets from the original 16 participants were produced; one participant (P-8) completed two sessions. (The reinforcement schedules and parameters for each participant can be obtained from the Supporting Information on the Wiley Online Library.) Apparatus and Settings Participants were situated in a room (3 m by 3 m) with a desk (with laptop computer) and chair. The participant was asked to be seated while the instructions were read to him or her. The participant was asked to read along with the instructions on the computer screen, and to begin the session when he or she was ready. The instructions included the following statement: Thank you for your participation in this study. Your goal is to earn as many points as possible before time is up. There is a possibility of earning up to $50 (with other monetary rewards for second and third place). There are different ways to earn points. Clicking on the colored buttons in different patterns could add to your earnings, not affect your earnings, or subtract from your earnings. All of your earnings will be visible throughout the experiment at the top of the screen, and a tone will sound with each distribution. Your time here will approximate 1 hour with a minute break every 5 minutes. You are free to leave at any point during this study; however, you will only be eligible to win the monetary prizes on completion. Remember, you are trying to beat other participants so do your best! Click the START button when you are ready and good luck! The program was created using Microsoft Visual Basic and consisted of 24 colored squares (100 by 100 pixels) in the center of the screen with a text bar at the center top that displayed real-time point accumulation. The colors of the squares differed depending on the programmed reinforcement schedule. The squares were stationary, and each click on a square made the square disappear. All the squares that were clicked regenerated after 6 s. Therefore all 24 squares were visible every 6 s, and at no time was the participant left without any squares to click. VARIATIONS OF DIFFERENTIAL REINFORCEMENT Design and Response Measurement The computer program automatically recorded mouse clicks. Every 1 s, a preset automated timer recorded the current frequency of clicks and points to a notepad file. Clicks were recorded if they occurred on the squares. All other clicks on the gray background produced no differential consequences and were not recorded. The primary dependent variable was rate of mouse clicks expressed as responses per second. ABA(C þ D) reversal designs were conducted to assess possible effects between baseline and the variations of the differential-reinforcement conditions. The initial reinforcer assessment (ABA) consisted of three VR (A) blocks, followed by three blocks of extinction (B), and a return to the VR blocks. The imbedded multielement (C þ D) design was implemented within treatment conditions to assess possible differentiating results of the DRL IRT (C) and the DRO rate (D). The design was extended to an ABA(C þ D)ACAD for the one participant who opted to participate for two sessions. However, all were given the opportunity to participate for both sessions. Procedure Sessions lasted a minimum of 60 min and consisted of three or more sequential 5-min blocks, for a total of 12 to 15 blocks each session. An optional 1-min break followed each block, and a 5-min break followed every six blocks. Points were delivered for mouse clicks based on the relevant schedule of reinforcement in place. After completion of the study, monetary rewards of $50, $40, and $10 were awarded to the participants who earned the most, second-most, and third-most amount of points, respectively. The initial nine blocks of each session consisted of a reinforcer assessment. The reinforcer assessment was comprised of three blocks of alternating extinction and VR schedules in an ABA reversal design. The reinforcer assessment was conducted to ensure that point delivery increased responding. 317 Participants could not earn points during the extinction phase. This arrangement included blue squares that did not disappear when clicked (the squares disappeared contingent on each click during the reinforcement phases). We elected not to remove squares contingent on clicks during extinction, because three pilot participants continued to click on the squares during sessions in which points were never delivered. During the VR phase, points were presented on a VR 15 ( 5) schedule of reinforcement. The scheduled mean number of responses was selected based on pilot data that indicated that responding would persist under a VR 15 ( 5). The algorithm used to generate the VR schedule was based on that provided by Dixon and MacLin (2003). This schedule was correlated with green squares. The VR schedule constituted the reinforcement condition in the reinforcer assessment and the baseline condition in the comparative differential reinforcement assessment. During the spaced-responding DRL phase, points were presented contingent on the first instance of a mouse click that followed the completion of a preset interval in which no responding occurred. The initial IRT interval was calculated as twice the mean IRT interval during the last VR phase. If clicks occurred at any point before the interval elapsed, the automated timer reset to the original IRT and no points were delivered. Points were not presented following the interval if no response occurred and were withheld, without restarting the timer, until the target response was emitted. This schedule was correlated with yellow squares. Both the spaced-responding DRL IRT and the full-session DRL interval were calculated from responding during the VR phase. During the fullsession DRL phase, the interval duration was calculated as four times the average IRT during the VR phase. Tolerance for the full-session DRL was defined as the maximum frequency of responding that could occur without resetting the reinforcer-delivery interval. Tolerance was calculated as half the mean response rate of the 318 JOSHUA JESSEL and JOHN C. BORRERO target response during the VR condition. For example, if the mean IRT during the VR phase was 2 s, the spaced-responding DRL would be calculated as 4 s (i.e., IRT > 4 s), the full-session DRL interval would be set as 8 s, and tolerance would be set as one response. Therefore, the scheduled probability of reinforcer delivery during the full-session DRL sessions remained proportional to the spaced-responding DRL condition. Although this method resulted in an interval substantially longer than DRO intervals typically conducted in applied contexts (see Vollmer & Iwata, 1992), without this modification comparative results between the spacedresponding DRL and full-session DRL procedures would not be mutually interpretable. Decreased response rates during the spacedresponding DRL are a function of increased IRTs and longer intervals, relative to some baseline response rate. On the other hand, short intervals are preferred during DRO arrangements to reduce the negative side effects of extinction and increase contact with the scheduled reinforcement. Thus, we elected to increase the fullsession DRL interval rather than decrease the spaced-responding IRT because decreases in spaced-responding DRL durations relative to a full-session DRL interval would have contraindicative or no effects on responding that was already occurring slower than the imposed rate. For example, if a participant is already responding at a pace of one response every 10 s, a minimum IRT of 5 s would not likely affect behavior. In addition, in comparison to the full-session DRL intervals commonly conducted in applied settings, the currently calculated intervals were relatively small. The intervals from Dietz and Repp (1973) consisted of entire class periods of 50 min. The negative effects often associated with long intervals may be avoided by the addition of tolerance. During the full-session DRL condition, points were delivered following the elapse of the interval, whether or not any clicks occurred at any time during the session block. However, if the frequency of clicks exceeded that of the set tolerance within the interval, points were not delivered and the interval was restarted immediately after the violation of tolerance. This condition was correlated with red squares. Data Analysis Data from a cumulative record were analyzed across 300 1-s bins per session to determine comparative optimal and allowable response rates during the last sessions of the spaced-responding DRL and full-session DRL conditions, respectively. The optimal response rate refers to the rate of responding during the spaced-responding DRL condition in which the most reinforcers can be produced within the allotted session time. The allowable response rate refers to the rate of responding during the full-session DRL condition in which all reinforcers can be delivered within the allotted session time without penalty of point loss. The slope of the cumulative data during the last session of each condition (i.e., VR, spaced-responding DRL, full-session DRL) was calculated by taking the response frequency at 10 s (Y1), subtracting it from the response frequency at 290 s (Y2), and dividing the difference by 280 (X2–X1). A contingency strength analysis (Luczynski & Hanley, 2009, 2010) was conducted to provide a quantifiable value of the contingent relations during the spaced-responding DRL phase and the full-session DRL phase. The contingency value was defined as the difference of two disparate conditional probabilities: response conditional probability and point conditional probability. A positive contingency value from the contingency strength analysis supports a correlation between a response and a reinforcer; the higher the positive value the stronger the correlation. Therefore, responses with positive contingencies are more likely to be strengthened, whereas negative contingencies are more likely to be weakened. By definition, for example, DRO arrangements promote a negative contingency between responding and reinforcer presentation VARIATIONS OF DIFFERENTIAL REINFORCEMENT (Vollmer, Borrero, Wright, Van Camp, & Lalli, 2001). The response conditional probability was the quotient of the number of responses followed by a point (1-s window) divided by the total number of responses. A 1-s window was selected for two reasons: (a) Previous research that has compared window sizes suggests that short window sizes (i.e., 2 s to 5 s) provide a more conservative measure (Luczynski & Hanley, 2009), and (b) little variance was observed between 1 s and 3 s for the current data. The point conditional probability was defined as the quotient of the number of points not preceded by a response (1-s window) divided by the total number of points delivered. Therefore, a continuous reinforcement schedule will result in a positive contingency value of 1 because the response will always precede reinforcer delivery. In contrast, a DRO schedule without tolerance will result in a contingency value of 1 because the numerator of the response conditional probability will always be 0 (i.e., zero responses will be followed by a point within 1 s). The contingency strength analysis was conducted to determine whether or not the full-session DRL schedule resulted in positive contingencies similar to most differential reinforcement schedules or in a negative contingency, as is the case with the DRO schedule. RESULTS Figures 1 through 3 depict the results of the reinforcer assessment and the comparison of response-reducing differential reinforcement techniques for all participants as responses per second. The solid horizontal line represents the optimal performance during the spacedresponding DRL condition, and the dashed horizontal line represents the allowable performance during the full-session DRL condition. Both differential reinforcement techniques reduced responding compared to baseline for all participants. Furthermore, all participants continued to respond during the spaced-responding 319 DRL condition, whereas 60% of participants ceased responding during the final blocks of the full-session DRL condition. Seven of the 10 participants produced response rates below optimal performance during the spaced-responding DRL conditions and did not maximize the total possible points that could have been earned (mean difference from optimal ¼ 36.7%; range, 13.3% to 85.6%). However, P-19 (Figure 2, bottom left) exhibited near optimal responding (0.74 responses per second) during the final spaced-responding DRL session (difference from optimal ¼ 2.8%). Three participants’ rate of responding was above optimal (mean difference from optimal ¼ 40.8%; range, 14.6% to 63.5%) with P-12 (Figure 1, bottom right) exhibiting near optimal responding (0.7 responses per second) during the final spacedresponding DRL session (difference from optimal ¼ 1.3%). The full-session DRL schedule resulted in all but P-4 (Figure 1, top left) producing mean response rates (M ¼ 0.11 responses per second; SD ¼ 0.13) below allowable performance (mean difference from allowable ¼ 62.7%; range, 100% to 86.5%). Furthermore, there was a 20.4% difference from the allowable performance for the only participant (P-4) who continued to respond near allowable (0.51 responses per second). Results of the contingency strength analyses for all 10 participants were positive (M ¼ 0.71; SD ¼ 0.26) during the spaced-responding DRL condition, and greater than that of the VR schedule value (0.07). The top panel of Figure 4 shows data for P-21, a representative example of the contingency strength analysis. That is, during the spacedresponding DRL condition, the response conditional probability exceeded the point conditional probability. In addition, negative contingency values (M ¼ 0.82; SD ¼ 0.28) were obtained for 9 of 10 participants during the full-session DRL condition. The bottom panel of Figure 4 shows data for P-4, who was the only participant to continue to respond at near allowable rates during JOSHUA JESSEL and JOHN C. BORRERO 320 CLICKS (RPS) 3 VR 15(±5) 3 VR 15( ±5) 2 2 1 1 0 P-4 0 5 3 CLICKS (RPS) EXT 10 15 2 1 1 P-7 0 5 10 BLOCKS 15 EXT VR 15( ±5) Optimal Allowable DRL-s DRL-f P-11 5 3 2 0 VR 15(±5) 10 15 10 15 P-12 5 BLOCKS Figure 1. Response rates during the variable ratio (VR), extinction (EXT), spaced-responding DRL (DRL-s), and fullsession DRL (DRL-f ) conditions across sessions for P-4, P-11, P-7, and P-12. The solid horizontal line depicts the optimal response rate for producing the most points during the spaced-responding DRL condition. The dashed horizontal line depicts the allowable response rate without resetting point delivery during the full-session DRL condition. RPS ¼ responses per second. the full-session DRL condition, and who showed the highest mean negative contingency (M ¼ 0.11; SD ¼ 0.16) with the last session a positive value (0.06) comparable to that of the positive VR value (0.07). We also evaluated responding during the VR, spaced-responding, and DRL conditions as a proportion of responding during each participant’s extinction condition. The greatest proportional increase in responding compared to extinction occurred in the VR for all participants. In addition, 90% of the participants displayed higher rates of proportional responding during the spaced-responding DRL condition (M ¼ 2.96; SD ¼ 1.72) compared to extinction. Notably, 30% of the participants displayed higher rates of proportional responding to extinction during the full-session DRL condition (M ¼ 0.54; SD ¼ 0.51). DISCUSSION These findings replicate previous research on DRL and DRO in that low-rate spaced-response patterns and the elimination of responding were obtained in the spaced-responding DRL and fullsession DRL conditions, respectively (Deitz & Repp, 1973). Although the full-session DRL schedule permitted a predetermined response rate derived from the participants’ baseline performances, many participants stopped responding. We also observed an overall negative contingency value consistent with a DRO-based schedule during the full-session DRL. Thus, the two schedules reduced responding compared to the VR schedule of reinforcement, with the full-session DRL arrangement resulting in the larger reduction. Although previous research has supported the use of full-session DRL schedules over spaced- VARIATIONS OF DIFFERENTIAL REINFORCEMENT CLICKS (RPS) 3 VR 15(±5) 3 VR 15( ±5) 2 2 1 1 0 P-15 0 5 3 CLICKS (RPS) EXT 10 15 2 1 1 P-19 0 5 10 BLOCKS 15 EXT VR 15( ±5) Optimal Allowable DRL-s DRL-f P-17 5 3 2 0 VR 15(±5) 321 10 15 10 15 P-21 5 BLOCKS Figure 2. Response rates during the variable ratio (VR), extinction (EXT), spaced-responding DRL (DRL-s), and fullsession DRL (DRL-f ) conditions across sessions for P-15, P-17, P-19, and P-21. The solid horizontal line depicts the optimal response rate for producing the most points during the spaced-responding DRL condition. The dashed horizontal line depicts the allowable response rate without resetting point delivery during the full-session DRL condition. RPS ¼ responses per second. responding DRL schedules due to the ease of implementation (Deitz, 1977; Deitz & Repp, 1973), results of the present study suggest that functional differences in these procedures are not simply a matter of structural semantics. Evaluation and implementation of spaced-responding DRL and full-session DRL should be considered in the context of clinical or research goals. The more effortful approach (spacedresponding DRL) may be required when the goal is to sustain responding, albeit at rates lower than those produced under baseline conditions (e.g., applications to rapid eating, excessive hand raising, or tattling). In addition, the limitations of using spaced-responding DRL schedules (e.g., requires individual timers for each student to be reset following responding below the pro- grammed IRT) may be assuaged when considering the possibility of the use of widespread technology such as tablets in classroom settings. Applications could be created on tablets with which teachers could select the IRT for each student immediately before the start of classroom activities. The teacher would only have to click on the child’s name after each response to determine whether or not he or she met the criteria for reinforcer presentation. Future research could assess the use of programmatic schedules of reinforcement on handheld devices to reduce work-related effort needed to create individualized interventions for classwide implementation. The results of the contingency strength analysis also provide insight into the possible quantitative differences between the reductions JOSHUA JESSEL and JOHN C. BORRERO 322 VR 15(±5) CLICKS (RPS) 3 VR 15(±5) EXT 3 VR 15( ±5) Optimal Allowable 2 0 2 DRL-s 1 1 DRL-f P-18 0 5 10 BLOCKS EXT 15 P-8 5 15 25 BLOCKS Figure 3. Response rates during the variable ratio (VR), extinction (EXT), spaced-responding DRL (DRL-s), and fullsession DRL (DRL-f ) conditions across sessions for P-18 and P-8. The solid horizontal line depicts the optimal response rate for producing the most points during the spaced-responding DRL condition. The dashed horizontal line depicts the allowable response rate without resetting point delivery during the full-session DRL condition. RPS ¼ responses per second. in responding under the spaced-responding and full-session DRL schedules. The VR and spacedresponding DRL schedules both maintained higher rates than those observed during extinction. This should not be surprising, considering that a positive contingency between responding and point delivery existed for both VR and spaced-responding DRL schedules. Reductions were observed during the spaced-responding DRL sessions when mean rates were analyzed; however, the contingency value was actually greater than the comparative VR reinforcement schedule from a within-session perspective. An artificial reduction in response rates was created in spaced-responding DRL schedules by reinforcing larger IRTs relative to baseline response rates. In contrast, the full-session DRL schedule produced a negative contingency between responding and point delivery. A change in procedural taxonomy may be warranted. Currently, little distinction is made between the two variations of DRL schedules (e.g., Cooper, Heron, & Heward, 2007) although it is evident that they differ in process and application. Assuming the two DRL schedules to be equivalent could result in misapplication (i.e., inadvertently maintaining inappropriate behavior with the spaced-responding DRL or inadvertently eliminating appropriate behavior with the fullsession DRL). We suggest that the full-session DRL could be expressed as a variation of a DRO schedule and that the term DRO-with-tolerance schedules could be considered when reducing inappropriate behavior. In a very literal sense, a predetermined tolerated level of inappropriate behavior is overlaid on top of a DRO schedule. Not only does the definition of DRO with tolerance incorporate both components in the basic arrangement (alternative DRO DRL), but it also implicitly suggests targeting undesirable behaviors. This simplifies the categorical usage for practitioners as DRL schedules for appropriate behavior and DRO schedules for inappropriate behavior. Furthermore, modifying its classification to a DRO schedule (rather than the previously reported DRL schedule) may improve the selection of interventions by clarifying its effects, by highlighting the units of analysis, and by underscoring the behavioral mechanisms that are responsible for effects obtained therein. VARIATIONS OF DIFFERENTIAL REINFORCEMENT CONTINGENCY VALUE 1.0 P-21 DRL-s 0.5 0.0 -0.5 DRL-f -1.0 CONTINGENCY VALUE 1.0 P-4 0.5 0.0 -0.5 -1.0 2 BLOCKSKS 4 6 Figure 4. Data in the top panel illustrate a strong positive contingency between responding and point delivery (DRL-s) and a strong negative contingency between responding and point delivery (DRL-f ). These are representative data for 9 of 10 participants. Data in the bottom panel are those from P-4, the only participant who continued to respond at near allowable rates during the fullsession DRL condition. Our brief experimental arrangement also could be used to examine two previously reported explanations for the suppressant effects of DRO and whether similar outcomes would be observed with DRO schedules implemented with tolerance. One explanation is that “other behavior” that occurs contiguously with the presentation of the reinforcer displaces target responding (Ecott & Crtichfield, 2004; Poling & Ryan, 1982). The second explanation conceptualizes the DRO schedule as a form of negative punishment because responding delays reinforcer onset (Lattal, 2013). 323 The brevity of our procedures and emphasis on temporal properties of responding also lend themselves to evaluations for which mechanisms of timing are thought to be operative or important. Dube and McIlvane (2002) used this type of assessment approach to evaluate sensitivity to concurrent reinforcement schedules by individuals with intellectual disabilities. Interestingly, most of the participants’ responding in the current assessment was above optimal performance, resulting in mean pauses that were longer than the set IRT. This is directly juxtaposed with previous basic research with rats, in which subjects were more likely to engage in below optimal performances, resulting in mean pauses that were shorter than the set IRT (Mazur, 1994). Although little can be responsibly deduced from these differences due to the procedural variance between the present human operant arrangement and basic research with nonhumans, it may still be important to note for those interested in studying temporal dimensions of behavior. One limitation of the present study was the lack of multiple tolerance settings. It is therefore unknown if an increased ratio of allowable responses to the same interval duration would result in responding more similar to that under the spaced-responding DRL. The tolerance may have been too stringent and resulted in increased contact with the DRO-related contingency of the fullsession DRL schedule. However, many participants who discontinued responding reported the ability to continue without resetting the timer and in some cases reported the approximate full-session DRL interval and tolerance setting. 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Examining the generality of children’s preference for contingent reinforcement via extension to different responses, reinforcers, and schedules. Journal of Applied Behavior Analysis, 43, 397–409. doi: 10.1901/jaba.2010.43-397 Mazur, J. E. (1994). Learning and behavior. Englewood Cliffs, NJ: Prentice Hall. Poling, A., & Ryan, C. (1982). Differential-reinforcementof-other-behavior schedules. Behavior Modification, 6, 3–21. doi: 10.1177/01454455820061001 Shaw, R., & Simms, T. (2009). Reducing attentionmaintained behavior through the use of positive punishment, differential reinforcement of low rates, and response marking. Behavioral Interventions, 24, 249–263. doi: 10.1002/bin.287 Singh, N. N., Dawson, M. J., & Manning, P. (1981). Effects of spaced responding DRL on the stereotyped behavior of profoundly retarded persons. Journal of Applied Behavior Analysis, 14, 521–526. doi: 10.1901/jaba.1981.14-521 Turner, J. M., Green, G., & Braunling-McMorrow, D. (1990). 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Journal of Applied Behavior Analysis, 35, 89–93. doi: 10.1901/ jaba.2002.35-89 Received June 15, 2012 Final acceptance December 12, 2013 Action Editor, Michael Kelley Copyright of Journal of Applied Behavior Analysis is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. to do so," to keep students from prematurely reading the next page. The second page gives one of three sets of the instructions: "You will be shown a series of cards. Try to remember the (words on) (numbers on). (colors of) the cards . in the order they are shdwn." Each sheet can be !4 of a regular sized sheet of paper. The three data collection pages and the cover page can all by typed on one 8% X 11 in. sheet of paper. The three different sets of instructions can be printed on another page. Each data collection sheet contains six lines, numbered 1 to 6, and instructions to remember the (words on) (numbers on) (colors of) the cards in the order they were presented. For those instructed to "remember the word," data collection sheets should be arranged as follows: (a) recall words, (b) recall numbers, and (c) recall colors. For the "remember the number" group, the order is: (a) recall numbers, (b) recall words, and (c) recall colors. Finally, for those told to "remember the colors" the order is: (a) recall colors, (b) recall words, and (c) recall numbers. Take one of each type of booklet, randomly arrange them in a stack; take another three (one of each type), randomly arrange them and add them to the stack; and so on. This random ordering of the booklets and students' selection of where thev will sit determine their assignment to the three conditions. You assure identical treatment of the groups because you show them the cards in the same way and at the same time. u Conducting the Demonstration When all students have their booklets, ask t h e ~ nto open the booklet and read only the first page. Next, show the six cards for about 5 s each. Be sure to show each card for the same length of time by counting silently to the same number at a regular rate. After showing the cards, tell students to turn to the next page, follow the instructions, and continue through the booklet until they are finished. After the students have written as many items as they can recall, show them the cards again and have them score their own responses. Ask them to write on the cover page the number of words, numbers, and colors they got correct. Then ask them to assemble in groups according to what they were instructed to remember and to find the group mean for each of the three kinds of information. The main point of the activity is to demonstrate that, on the average, each group will have remembered more items in the category they were asked to remember. Only those asked to remember the colors of the cards get many of the colors correct. The same basic effect occurs in the other two groups, but to a lesser degree. Those with the "number" instructions usuallv remember more numbers than the other groups, and those with the "word" instructions tend to remember more words than the other groups. I conducted a 3 x 3 (Instructions x Recall Category) analysis of variance on the data from 30 students who participated in this demonstration. There was no main effect for instructions, F(2, 27) < 1, and no main effect for recall category, F(2, 54) = 2.08, ns, but there was a significant interaction, F(2, 54) = 17.70, p .< .01. The means and standard deviations for this sample are shown in Table 1. Table 1. Means and Standard Deviations of ltems Recalled Out of Six ltems in Each Category by Groups With Different lnstructionsa Items Recalled Color Word Number Instructions M SD M SD M SD Remember color Remember word Remember number 5.1 1.7 0.7 1.9 1.3 1.3 2.3 4.1 3.4 1.8 1.9 1.5 1.6 3.2 4.4 2.0 2.0 1.6 an = 10 per condition. What Does it Show? Some important elements of conducting an experiment are illustrated by the procedure. Subjects were randomly assigned to conditions, and all other variables were kept constant. A discussion of what the students were expecting can yield interesting information. Usually a couple of people figure out the experiment and remember the colors even though they were not instructed to do so. This fact can be used to illustrate that subjects in experiments often act as problem solvers. As the statistical analysis shows, students usually recall about the same number of items regardless of the instructions, and no one category is more memorable than any other. However, each group remembers best the category they were told to remember. I use the fact that attention increases memory to emphasize the importance of looking at chapter outlines or lists of learning objectives in the textbook before studying. Pay attention! Note Requests for reprints should be sent to Janet D. Larsen, Department of Psychology, John Carroll University, University Heights, OH 441 18. Demonstrating Differential Reinforcement by Shaping Classroom Participation Gordon K. Hodge Nancy H. Nelson University of New Mexico A classroom demonstration using differential reinforcement was devised to shape classroom participation of 14 students in an introductory psychology lab. Based on our observations and student comments, the technque was useful for illustrating how reinforcers shape behavior. The demonstration facilitated students' understanding of operant conditioning procedures and seemed to encourage a more equitable distribution of classroom participation for all students. Principles of operant conditioning are easily presented in Vol. 18, No. 4, December 1991 Downloaded from top.sagepub.com at Apollo Group - UOP on September 12, 2015 classroom demonstrations. For example, descriptions of students operantly shaping their instructors' behaviors have been reported (Chrisler, 1988; Melvin, 1988). As a variation on this theme, we devised a demonstration in which the instructor shapes the students' level of class participation using a differential reinforcement procedure. In our experience, uneven distribution of student participation in the classroom is common. In large lecture sections of 400 to 600 students, opportunities for participation are sometimes limited by time constraints and the intimidating atmosphere. But in small classes, such as seminars, labs, or discussion sections, the ideal scenario is one in which all students contribute, and discussions dominated by the assertive few are minimized. We strive to foster creative exchange and discussion of ideas in the introductory psychology labs. As stated in the syllabus, students receive a grade for class participation. They are encouraged and, presumably, motivated to take part in discussions; still, many students do not participate. In one lab section, we noted that three students overly participated in discussions at the expense of other students who rarely spoke. We believed it would be advantageous to foster more equitable interactions. We also saw an opportunity to implement an educationally valuable demonstration that would enhance previously learned class material. Method Subjects Subjects were 8 women and 6 men enrolled in an introductory psychology lab at the University of New Mexico. Materials Two weeks before the actual demonstration, students circled the value on a 7-point scale that best indicated their own level of class participation. The scale ranged from I never participate ( 1 ) to 1 always participate ( 7 ) . These ratings provided a baseline level of self-perceived participation for each student. After the demonstration and before debriefing, each student completed an anonymous questionnaire consisting of the following three items: 1. In your own words, describe the demonstration implemented during today's class. Include whether or not you believe the demonstration influenced your level of class participation. 2. Was the demonstration useful in illustrating how reinforcers may be used in an operant conditioning procedure? Explain how the demonstration was useful and possible ways it may be changed andlor improved. 3. Any additional thoughts concerning this demonstration. Design and Procedure One week after the lecture on learning, the lab instructor distributed the scale assessing each student's perceived level of class participation. T o avoid biasing the demonstration, students were not told the reason for filling out the questionnaire. The scale was used to assist the instructor in determining the appropriate differential reinforcement schedule to be implemented during the demonstration. The demonstration using differential reinforcement to shape classroom participation was implemented 2 weeks after the rating scales were distributed. Each student's initials were placed on the top of the chalkboard at the front of the class. The reinforcer consisted of a plus mark placed underneath a student's name whenever the desired behavior (increased or decreased participation) was emitted. The instructor determined before the demonstration which students would receive a reinforcer for either participating or not participating, based on the rating scales and familiarity with class dynamics. Among the 14 students, 3 were judged as overparticipators; they were reinforced only when they did not participate or interrupt or when specifically called on by the instructor after raising their hands. The 5 students who rarely participated were reinforced for making even the slightest effort to participate; for example, hand raising, saying anything (correct or not) when called on, and, in one instance, making eye contact with the instructor. These students were then reinforced less frequently as they began to emit more responses according to general shaping procedures (Gordon, 1989). The remaining 6 students normally participated in a moderate fash~onand were reinforced on a variable ratio schedule t~ maintain their active participation. Following the demonstration and before debriefing, a short questionnaire was given to assess whether the students caught on to the demonstration and to get their feedback and suggestions. Debriefing consisted of discussing the items on the questionnaire in a classroom forum and reemphasizing the principles of operant conditioning, shaping, and differential reinforcement. Results Student responses on the rating scale reflected the instructor's perceptions of participation levels. Only one student, rated by the instructor as a 1 (I never participate), placed a rating of 2 on his scale. The scales, therefore, appeared to complement the ratings made independently hv the instructor, providing a reasonably reliable tool for devising a differential reinforcement schedule for each student. Based on the instructor's subjective observation, class participation seemed noticeably more balanced after the technique was implemented. Overparticipators contributed much less; underparticipators contributed more often and enthusiastically. Only one of the identified underparticipators remained reticent. This balance in participation was noticed by 5 of the students on their questionnaires. One wrote that "people like an upbeat situation and are encouraged to join in," and another student noted that "btudents that [sic] don't normally contribute hegan to participate. " Based on the responses to the first item on the questionnaire, 12 of 14 students identified the demonstration as an example of operant conditioning or the use of ,I shaping Teaching of Psychology Downloaded from top.sagepub.com at Apollo Group - UOP on September 12, 2015 procedure or both. One student identified it as a motivational study (the demonstration was implemented during a lecture on motivation), and one student did not answer the question. In response to the second part of Item 1 (whether or not the demonstration influenced their level of class participation-either increasing or decreasing it), 10 of 14 students believed that the demonstration affected their class participation. One student stated "I think some people talked a lot more than usual," and another stated "many students gave input that usually do not." The other 4 students did not believe the demonstration affected their participation. In response to Item 2, 12 of the 14 students found the demonstration useful in illustrating the role of reinforcers in an operant conditioning procedure, noting that the demonstration was "closely related to our computer assignment" (which dealt with shaping) and better "integrated our lecture notes." Four students mentioned that they would prefer a more potent reinforcer, such as extra credit, rather than "just a plus mark." Discussion The demonstration was a valuable and worthwhile way to illustrate differential reinforcement in shaping classroom participation. The usefulness of the demonstration, based on responses to the questionnaire, is evident, although there are obvious limitations. The demonstration is limited to a small class size (approximately 20 students) in order for the instructor to implement an effective differential reinforcement procedure tailored for each student. With larger groups, it would be difficult to keep track of the target responses and dispense reinforcers in a timely fashion. Of some concern was how students, particularly overparticipators, perceived the fairness of the procedure. For example, overparticipators might have wondered why others received plus marks and they did not. On the questionnaires, two students expressed frustration for not receiving reinforcement of their active participation. One student wrote that the activity was "quite frustrating, considering that I didn't get a plus until the latter portion of the demonstration after participating considerably." That overparticipators experienced frustration when their normally high participation levels went unrewarded was not surprising. In general, overparticipators seem frustrated whenever the instructor fails to call on them or limits their comments. The concern is whether frustration elicited by the demonstration was notably different from feelings ordinarily elicited during routine classroom management. l ~ to initial mispercepSome frustration was ~ r o b a b due tions that the goal was to increase everyone's participation equally, rather than differentially. As the demonstration progressed, however, overparticipators responded by curtailing their behavior in order to earn plus marks. One student's strategy provided insight into the process: "I initially increased participation to ascertain whether I would receive points. This attempt was to no avail so I proceeded to lessen my degree or amount of participation" (for which the student was then reinforced). Although frustration occurred, there were no indications from questionnaire responses or discussions during debriefing that overparticipators thought the experience was unfair. Both students who expressed ini- tial frustration reported that the demonstration was interesting and useful. Nevertheless, instructors should be alert for signs of unusual discomfort or frustration and be ready to end the demonstration and initiate debriefing as necessary. In discussing the demonstration with students, it is worthwhile to point out that the changes in participation frequencies probably reflected a real-life application of an operant conditioning procedure. Moreover, even though students became aware of the purpose of the demonstration while it was ongoing, their behavior nevertheless changed in response to the procedures (cf. Blanchard & Johnson, 1982). Discussion could then focus on students' ideas of how similar procedures could be applied in other situations (e.g., encouraging more balanced communication in a personal relationship). Althoughnot quantified, some positive effectson class participation appeared to remain throughout the semester. This pleasant residual effect may have occurred because students and instructor were now more aware of their class behavior. Students who normally did not participate may have felt more comfortable about contributing after their first experience in speaking, or, possibly, the class dynamics became less threatening and more comfortable to these students. Ways to improve this demonstration include developing a more objective, less intrusive assessment of class participation in addition to the questionnaire. One possibility would be to use a hidden tape recorder or video camera to record a baseline session before the demonstration, record the demonstration, and then have an objective third party score the tape(s). The demonstration is a useful technique for illustrating differential reinforcement and for encouraging more equitable participation in small classes. References Blanchard, K., & Johnson, S. (1982). The one minute manager. New York: Berkley. Chrisler, J. C. (1988). Conditioning the instructor's behavior: A class project in psychology of learning. Teaching of Psychology, 15, 135-137. Gordon, W. C. (1989). Learning and memory. Pacific Grove, CA: BrooksICole. Melvin, K. B. (1988). Rating class participation: The proflpeer method. Teaching of Psychology, 15, 137-139. Notes 1. We thank Frank A. Logan, Charles L. Brewer, and the anonymous reviewers for their helpful comments. 2. Requests for reprints should be sent to Gordon K. Hodge, Department of Psychology, University of New Mexico, Albuquerque, NM 87131. Demonstrating Personality Scale Validation Procedures Robert C. Reinehr Southwestern University A technique is described for demonstrating personality scale walidation techniques to students in introductory psychology classes. Vol. 18, No. 4, December 1991 Downloaded from top.sagepub.com at Apollo Group - UOP on September 12, 2015 Copyright of American Journal of Psychotherapy is the property of Association for the Advancement of Psychotherapy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
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