Preference for mixed versus constant delays of reinforcement: Effect of probability of the short, mixed delay

Preference for mixed versus constant delays of reinforcement was studied with a concurrent-chain procedure. Lever pressing by rats in concurrently available variable-interval 60-second initial links occasionally produced mutually exclusive terminal-link reinforcement delays. A constant delay of reinforcement (either 15 seconds or 30 seconds) composed one terminal link and mixed delays (.2 second and twice the value of the constant delay) were arranged in the other terminal link. The proportion of .2-second delays in the mixed-delay terminal link took on values of 0, .1, .25, .5, .75, .9, and 1.0 over experimental conditions. Based on relative rates of responding in the initial links, preference for the mixed delays was a negatively accelerated function of the proportion of short, mixed delays. Three of five rats preferred the mixed delays to the constant delays when the proportion of short, mixed delays was .1 or higher, and all five rats preferred the mixed delays when the proportion of short, mixed delays was .25 or higher. Neither Squires and Fantino's (1971) delay-reduction model of choice nor a model based on the harmonic mean reinforcement delay provided a close estimate of choice proportions over the range of short-delay proportions studied. The delay-reduction model underestimated choice for the mixed delays at low and intermediate proportions of short delays, and the harmonic-mean-delay model overestimated choice for the mixed delays at intermediate and high proportions of short delays.     

Hill-climbing by pigeons

Pigeons were exposed to two types of concurrent operant-reinforcement schedules in order to determine what choice rules determine behavior on these schedules. In the first set of experiments, concurrent variable-interval, variable-interval schedules, key-peck responses to either of two alternative schedules produced food reinforcement after a random time interval. The frequency of food-reinforcement availability for the two schedules was varied over different ranges for different birds. In the second series of experiments, concurrent variable-ratio, variable-interval schedules, key-peck responses to one schedule produced food reinforcement after a random time interval, whereas food reinforcement occurred for an alternative schedule only after a random number of responses. Results from both experiments showed that pigeons consistently follow a behavioral strategy in which the alternative schedule chosen at any time is the one which offers the highest momentary reinforcement probability (momentary maximizing). The quality of momentary maximizing was somewhat higher and more consistent when both alternative reinforcement schedules were time-based than when one schedule was time-based and the alternative response-count based. Previous attempts to provide evidence for the existence of momentary maximizing were shown to be based upon faulty assumptions about the behavior implied by momentary maximizing and resultant inappropriate measures of behavior.     

Duration-reduction of avoidance sessions as negative reinforcement

Five rats were exposed to a shock-postponement procedure in which responses on each of two levers initially had equivalent effects. After an initial training sequence that ensured at least some responding on each lever, an additional consequence was made conjointly operative on the previously less-preferred lever for each animal. Each response on this lever continued to postpone shock, but also reduced the session duration by one minute. The conjoint contingencies were operative until, through session-shortening responses and the passage of time, the session was scheduled to end in two minutes; during the final two minutes the session-shortening contingency was disabled while the shock-postponement contingency continued to be operative on both levers. When responding shifted to a predominance on the session-shortening lever, the conjoint contingency was shifted to the other lever; for four of the five rats this reversal was followed by two additional reversals. Two of the rats' responding showed clear, strong, and unambiguous sensitivity to the session-shortening contingency. The responding of two others was also systematically controlled by that contingency, but the effects were less clearcut. The fifth animal showed an initial shift when session-shortening was introduced, but its subsequent behavior proved insensitive to reversals of procedure. The results clearly indicate a sensitivity of behavior to events on a time scale quite distinct from that of immediate consequences. They also support an interpretation of avoidance sessions, considered in their entirety, as events whose contingent relationship to behavior can affect that behavior—even in the absence of stimuli that delineate those relationships. Finally, these results support an interpretation of aversively based conditioning within a broader context, analogous to the “open versus closed economy” interpretation of appetitively controlled behavior.     

Some values guiding community research and action

The dual purposes of applied research-contributing to understanding and improvement-are only partially served by method systems that encourage studying (with increasing precision) a narrow range of questions of modest societal importance. To optimize contributions to challenging societal problems, a field's cherished standards should be adapted to support more adventuresome forms of community research and action. This paper outlines 10 values for community research and action, based on insights from the fields of behavioral and community psychology. These values-reflect the goals and challenges of establishing collaborative relationships with research participants, determining research goals and methods, designing and disseminating interventions, communicating research findings, and advocating for community change. Critical challenges are outlined, and implications for the field and its clients are discussed.     

FUNCTIONAL ASSESSMENT,CURRICULAR REVISION,AND SEVERE BEHAVIOR PROBLEMS

An adolescent female with multiple handicaps and a long history of severely disruptive behavior participated in a functional assessment linked directly to specific revisions in her school curriculum. During Phase 1, reversal designs were used to test hypotheses pertaining to antecedent and auricular influences on problem behavior. During Phase 2, a multiple baseline across afternoon and morning time periods demonstrated that the auricular revisions were effective in eliminating severely disruptive behavior and increasing on-task responding. Data also showed that inappropriate “psychotic” speech was reduced and appropriate social interactions were increased. Follow-up results showed that the changes were maintained throughout the school year. Questionnaire data provided social validation of the procedures and outcomes. The findings are discussed in relation to their implications for functional assessment, individualized curricula, and positive programming for students with disabilities and serious behavior problems.     

FUNCTIONAL COMMUNICATION TRAINING TO REDUCE CHALLENGING BEHAVIOR: MAINTENANCE AND APPLICATION IN NEW SETTINGS

We evaluated the initial effectiveness, maintenance, and transferability of the results of functional communication training as an intervention for the challenging behaviors exhibited by 3 students. Assessment indicated that escape from academic demands was involved in the maintenance of the challenging behaviors. Social attention was also implicated as controlling the behavior of 1 student. The intervention involved teaching alternative assistance-seeking and attention-getting phrases to the students in an effort to replace challenging behavior with these verbal equivalents. Multiple baseline data collected across the 3 students indicated that not only did the intervention substantially reduce challenging behavior but also that these results transferred across new tasks, environments, and teachers, and were generally maintained from 18 to 24 months following the introduction of functional communication training. These results are discussed in light of recent efforts to develop effective interventions for severe challenging behavior and to understand the processes underlying transfer and maintenance of intervention effects.     

COMMUNITY INTERVENTION TO DETER ILLEGAL PARKING IN SPACES RESERVED FOR THE PHYSICALLY DISABLED

Illegal use of reserved parking spaces represents a major obstacle to the independence and mobility of people with physical disabilities. Using an ABACACA reversal design, the daily rates of illegal parking in four reserved spaces were examined across three types of sign displays: (a) a vertical sign alone or in combination with (b) a message sign that announced the possibility of public surveillance or (c) a message dispenser device that announced community involvement and dispensed politely worded reminder notes. The average rate of illegal parking dropped from 51.3% during the initial vertical sign phase to 37.3% under the message sign condition, followed by an increase to 50.4% when the message was removed. Illegal parking decreased to 24.5% when the message dispensers were first used (followed by an increase to 57.0% when they were removed) and to 23.7% when the message dispenser condition was repeated. Illegal parking in the final vertical sign condition failed to return to previous levels (M = 37.3%).     

ENFORCEMENT OR INCENTIVES? PROMOTING SAFETY BELT USE AMONG MILITARY PERSONNEL IN THE NETHERLANDS

During a nationwide campaign to promote safety belt use among military personnel, a field study was conducted at 12 different military bases in the Netherlands. Amount of enforcement, type of publicity, and incentive strategies were varied among military bases. Observations of safety belt use among servicemen in their personal vehicles were conducted before the campaign, immediately following the campaign, and 3 months later. Safety belt use increased from 65% during baseline to 73% directly after the campaign and to 76% 3 months later. An overall 28.6% increase in safety belt use (from 63% to 81%) was observed at seven bases, whereas no changes were found at five bases (68% on all occasions). To a large degree the effects were due to a 37.7% increase among young drivers. These results confirmed that enforcement, as well as incentives, can be effective in promoting safety belt use. However, treatment effects were not systematic, thereby complicating the interpretation of the results. Implications of these varied outcomes are discussed.