Effects Of Histories Of Differential Reinforcement Of Response Rate On Variable-interval Responding

Stimulus generalization of behavioral history: Interspecies generality and persistence of generalization gradients

Four pigeons were exposed to a tandem variable-interval (VI) fixed-ratio (FR) schedule in the presence of a 50-pixel (about 15 mm) square or an 80-pixel (about 24 mm) square and to a tandem VI differential-reinforcement-of-low-rate (DRL) schedule when a second 80-pixel or 50-pixel square was present. The values of the VI and FR schedules were adjusted to equate reinforcement rates in the two tandem schedules. Following this, a square-size continuum generalization test was administered under a fixed-interval (FI) schedule or extinction. In the first testing session, response frequency was a graded function of the similarity of the test stimuli to the training stimuli for all pigeons. These systematic generalization gradients persisted longer under the FI schedule than under extinction.

AN EVALUATION OF RESURGENCE DURING FUNCTIONAL COMMUNICATION TRAINING

Three children who displayed destructive behavior maintained by negative reinforcement received functional communication training (FCT). During FCT, the children were required to complete a demand and then to mand (touch a card attached to a microswitch, sign, or vocalize) to receive brief play breaks. Prior to and 1 to 3 times following the initiation of FCT, extinction probes were conducted to evaluate the resurgence of destructive behavior when the microswitch without the mand card was present or the microswitch and the mand card were absent to determine if different patterns of resurgence occurred when the microswitch was present or absent and, for 2 of the children, if changes in resurgence occurred at different points in treatment. Results showed that FCT led to relatively rapid reductions in destructive behavior. During all extinction sessions, resurgence of destructive behavior occurred with only minimal differences across the switch/no card and no-switch conditions.

Some determinants of remote behavioral history effects in humans

Undergraduates were exposed to a series of reinforcement schedules: first, to a fixed-ratio (FR) schedule in the presence of one stimulus and to a differential-reinforcement-of-low-rate (DRL) schedule in the presence of another (multiple FR DRL training), then to a fixed-interval (FI) schedule in the presence of a third stimulus (FI baseline), next to the FI schedule under the stimuli previously correlated with the FR and DRL schedules (multiple FI FI testing), and, finally, to a single session of the multiple FR DRL schedule again (multiple FR DRL testing). Response rates during the multiple FI FI schedule were higher under the former FR stimulus than under the former DRL stimulus. This effect of remote histories was prolonged when either the number of FI-baseline sessions was small or zero, or the time interval between the multiple FR DRL training and the multiple FI FI testing was short. Response rates under these two stimuli converged with continued exposure to the multiple FI FI schedule in most cases, but quickly differentiated when the schedule returned to the multiple FR DRL.

Efeitos do reforçador empregado em história de reforço recente e remota

Doze universitários, distribuídos em quatro grupos, clicaram com o mouse sobre um botão na tela de um computador. Os participantes dos Grupos 1 e 3 foram expostos à seqüência FR - DRL - FI e os dos Grupos 2 e 4 à seqüência DRL - FR - FI. Os reforçadores foram pontos trocados por dinheiro (Grupos 1 e 2) ou pontos apenas (Grupos 3 e 4). Efeitos de histórias recentes em FI foram preponderantes quando pontos foram trocados por dinheiro. História, recente ou remota, de DRL afetou o comportamento subseqüente principalmente quando o reforçador consistia de pontos apenas. Sugere-se que o reforçador empregado modula efeitos de história em FI e que sua manipulação pode esclarecer discrepâncias entre humanos e não-humanos sob programas de reforço.

Applied implications of reinforcement history effects

Although the influence of reinforcement history is a theoretical focus of behavior analysis, the specific behavioral effects of reinforcement history have received relatively little attention in applied research and practice. We examined the potential effects of reinforcement history by reviewing nonhuman, human operant, and applied research and interpreted the findings in relation to possible applied significance. The focus is on reinforcement history effects in the context of reinforcement schedules commonly used either to strengthen behavior (e.g., interval schedules) or commonly used to decrease behavior (e.g., extinction).

An analysis of reinforcement history effects

Four pigeons were exposed to two tandem variable-interval differential-reinforcement-of-low-rate schedules under different stimulus conditions. The values of the tandem schedules were adjusted so that reinforcement rates in one stimulus condition were higher than those in the other, even though response rates in the two conditions were nearly identical. Following this, a fixed-interval schedule of either shorter or longer values than, or equal to the baseline schedule, was introduced in the two stimulus conditions respectively. Response rates during those fixed-interval schedules typically were higher in the presence of the stimuli previously correlated with the lower reinforcement rates than were those in the presence of the stimuli previously correlated with the higher reinforcement rates. Such effects of the reinforcement history were most prominent when the value of the fixed-interval schedule was shorter. The results are consistent with both incentive contrast and response strength conceptualizations of related effects. They also suggest methods for disentangling the effects of reinforcement rate on subsequent responding, from the response rate with which it is confounded in many conventional schedules of reinforcement.

The role of terminal-link stimuli in concurrent-chain schedules: revisited using a behavioral-history procedure

A behavioral-history procedure was used to study the function of terminal-link stimuli as conditioned reinforcers in multiple concurrent-chain schedules of reinforcement. First, three pigeons were exposed to multiple concurrent-chain schedules in which the two multiple-schedule components were correlated with a blue and a white stimulus, respectively. In each component the initial links were equal independent variable-interval (VI) 15 s schedules. A fixed-interval (FI) 10 s schedule operated on the red key in one terminal link while extinction operated on the green key in the alternative terminal link. When large preferences for the red stimulus had been established, two tests were conducted. In the terminal-link test, under new initial-link stimuli--purple and brown--an FI 10 s schedule operated for both the red and green terminal-link stimuli. In the subsequent initial-link test, the blue and white initial-link stimuli were reintroduced, and, as in the terminal-link test, FI 10s operated for both the red and the green terminal-link stimuli. In the terminal-link test, the three pigeons showed no preference for the terminal links with the red stimulus, but showed clear and consistent preferences for the red stimulus when blue and white stimuli were reintroduced as initial-link stimuli in the initial-link test. This suggests that there are multiple sources of control over initial-link response allocation in concurrent-chains, including control by both terminal- and initial-link stimuli.

Effects of experience on preference between forced and free choice

Preference between forced choice and free choice in concurrent-chain schedules of reinforcement was investigated in pigeons after exposure to particular combinations of terminal links. In Experiment 1, in which terminal links always ended with reinforcers, one of three pairs of terminal links was arranged as preexposure: (a) both terminal links had only one key (forced choice), (b) both terminal links had two keys (free choice), or (c) a combination of forced and free choice was arranged across sessions. In test sessions following the preexposure, pigeons' preferences rapidly shifted to the terminal links with which they had no recent experience. In Experiment 2, the same procedure was repeated except that each terminal link ended intermittently with reinforcers with a probability of .5 and there was no terminal-link arrangement with a combination of free and forced choice. Pigeons showed the same preference changes as in Experiment 1, but the preference changes did not appear immediately at the beginning of test sessions. These data suggest that recent previous experience was a more important determinant of preference than the difference between forced-choice and free-choice terminal links.

Stimulus generalization of behavioral history

Undergraduates responded under a variable-ratio 30 schedule in the presence of a 25-mm long line and on a differential-reinforcement-of-low-rate 6-s schedule when a 13-mm long line was present. Following this, a line-length continuum generalization test was administered under a fixed-interval 6-s schedule (Experiment 1) or extinction (Experiment 2). In both experiments, obtained generalization gradients conformed to typical postdiscrimination gradients. Responses were frequent under stimuli physically similar to the 25-mm line and infrequent under stimuli physically similar to the 13-mm line. The generalization gradients were generally asymmetric with peak response rates occurring at line lengths greater than 25 mm.

Carryover effects of free reinforcement on children's work completion

Patterns of behavior that persist during transition to a new set of contingencies are referred to as reinforcement history or carryover effects. The authors examined the carryover effects of a fixed-time (FT) schedule of free reinforcement on children's work completion and accuracy. Two female students with learning disabilities participated. During an initial concurrent-choice condition, both children completed more difficult problems reinforced on a richer schedule than easy problems reinforced on a leaner schedule. Exposure to an FT schedule was alternated with subsequent choice conditions in an ABABA design to examine potential carryover effects. During FT conditions, the children completed both types of problems with more errors. During subsequent choice conditions, errors were high initially but decreased, and both children completed easy problems for the first few sessions despite their leaner reinforcement schedule. The potential for detrimental effects of free reinforcement on children's work completion is discussed.

Effects of differences in interreinforcer intervals between past and current schedules on fixed-interval responding

Undergraduates were exposed to a mixed fixed-ratio differential-reinforcement-of-low-rate schedule. Values of the schedule components were adjusted so that interreinforcer intervals in one component were longer than those in another component. Following this, a mixed fixed-interval 5-s fixed-interval 20-s schedule (Experiment 1) or six fixed-interval schedules in which the values ranged from 5 to 40 s (Experiment 2) were in effect. In both experiments, response rates under the fixed-interval schedules were higher when the interreinforcer intervals approximated those produced under the fixed-ratio schedule, whereas the rates were lower when the interreinforcer intervals approximated those produced under the different-reinforcement-of-low-rate schedule. The present results demonstrate that the effects of behavioral history were under control of the interreinforcer intervals as discriminative stimuli.