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In Experiment 1, the choice responses of 8 pigeons were observed during 50 periods of transition. Each condition began with equal probabilities of reinforcement on 2 response keys and switched to unequal probabilities. With the ratio of the 2 probabilities held constant, preference for the higher probability developed more rapidly when the 2 probabilities were high than when they were low. In Experiment 2, each condition began with 2 equal variable-interval schedules, but later 1 key delivered 60%, 75%, or 90% of the reinforcers. The rate of approach to asymptotic performance was roughly the same with all 3 reinforcement percentages. These and previous results pose difficulties for some well-known models of acquisition, but the results are well described by a simple model that states that the strength of each response is independently increased by reinforcement and decreased by nonreinforcement.

Five types of depersonalization experiences based on scales developed by Jacobs and Bovasso (1992) were used to cluster subjects into six groups. Four relatively small groups which had regular depersonalization experiences were identified: the Derealized, the Self-negating, the Body-detached, and the Profoundly Depersonalized. The fifth group, the Fleetingly Depersonalized, and the sixth group, the Non-depersonalized, constituted 25% and 50% of the population, respectively. A profile analysis indicated qualitative differences between the six groups in their pathological traits, which fell along a continuum of pathological severity. The results support the validity of a multidimensional depersonalization construct which may clarify some of the contradictions and inconsistencies in the literature on depersonalization. Further, the results may facilitate clinicians' differentiation of their patients along a continuum of pathological severity based on the type and frequency of depersonalization experiences which they report.

Pigeons were presented with a concurrent-chains schedule in which terminal-link entries were assigned to two response keys on a percentage basis. The terminal links were fixed delays that sometimes ended with food and sometimes did not. In most conditions, 80% of the terminal links were assigned to one key, but a smaller percentage of the terminal links ended with food for this key, so the number of food reinforcers delivered by the two alternatives was equal. When the same terminal-link stimuli (orange houselights) were used for both alternatives, the pigeons showed a preference for whichever alternative delivered more frequent terminal links. When different terminal-link stimuli (green vs. red houselights) were used for the two alternatives, the pigeons showed a preference for whichever alternative delivered fewer terminal links when terminal-link durations were long, and no systematic preferences when terminal-link durations were short. This pattern of results was consistent with the predictions of Grace's (1994) contextual choice model. Preference for the alternative that delivered more frequent terminal links was usually stronger in the first few sessions of a condition than at the end of a condition, suggesting that the conditioned reinforcing effect of the additional terminal-link presentations was, in part, transitory.

The present study compared compliance, noncompliance strategies, and the correlates in 5-year old Japanese and American children were observed during three standardized laboratory procedures. Compliance, noncompliance strategies, and negative affect were coded during Toy Pick Up procedure. Maternal directiveness and mother-directed behaviors were coded during Mother-Child play and Free-play procedures, respectively. A baseline level of play was also obtained during the Free Play procedures to ensure that the children's willingness to engage in the Toy Pick Up procedure would not be confounded with their level of involvement with the toys. Consistent with predictions derived from a review of cross-cultural research on socialization practices, Japanese children showed longer latencies to begin picking up toys in response to maternal requests and were also more likely to engage in the `less skilled' noncompliance strategies of direct defiance and passive noncompliance than American children. The two groups of children did not, however, differ in their level of negative affect during the Toy Pick Up procedure. Contrary to expectations, maternal directiveness was not associated with compliance in either group of children. However, approach behavior to mother during Free Play was inversely correlated with compliance in Japanese, but not American children.

Direct behavioral observation and motility monitoring procedures provide reliable data, and both are appropriate for sleep/wake state measurements starting immediately after birth. Using these procedures, newborn rats, rabbits, and humans were found to have a greater amount of quiet sleep on the day of birth rather than 24 hr later. Changes in active sleep and wake were inconsistent across the 2 days. The quiet sleep findings are contrary to the developmental course which increases with age. The findings are interpreted as a temporary adaptive response to the stress of the birth process.

In Experiment 1, pigeons' pecks on a green key led to a 5-s delay with green houselights, and then food was delivered on 20% (or, in other conditions, 50%) of the trials. Pecks on a red key led to an adjusting delay with red houselights, and then food was delivered on every trial. The adjusting delay was used to estimate indifference points: delays at which the two alternatives were chosen about equally often. Varying the presence or absence of green houselights during the delays that preceded possible food deliveries had large effects on choice. In contrast, varying the presence of the gr een or red houselights in the intertrial intervals had no effects on choice. In Experiment 2, pecks on the green key led to delays of either 5 s or 30 s with green houselights, and then food was delivered on 20% of the trials. Varying the duration of the green houselights on nonreinforced trials had no effect on choice. The results suggest that the green houselights served as a conditioned reinforcer at some rimes but not at others, depending on whether or nor there was a possibility that a primary reinforcer might be delivered. Given this interpretation of what constitutes a conditioned reinforcer, most of the results were consistent with the view that the strength of a conditioned reinforcer is inversely related to its duration.

The current study examined the stability of mother-adolescent AIDS conversations. Twenty-four mother-adolescent dyads (9 boys, 15 girls) participated at Time 1 (adolescents aged 10-14 years), and again 2 years later. Mothers and adolescents engaged in a videotaped conversation about AIDS and completed AIDS questionnaires. Conversations were coded for content and the extent to which mothers dominated conversations. Conversational dominance remained stable over time. AIDS knowledge was greater for mothers than adolescents, but it improved over time for adolescents while remaining stable for mothers. Mothers who reported discussing AIDS-related topics with their adolescents had less discrepancy between their own and their children's AIDS knowledge. Conversational dominance at Time 1 predicted discrepancy in AIDS knowledge 2 years later, whereas discrepancy in AIDS knowledge at Time 1 did not predict conversational dominance two years later. These results suggest the importance of interactive conversations as a more effective way of teaching than didactic conversations.

Two experiments studied the phenomenon of procrastination, in which pigeons chose a larger, more delayed response requirement over a smaller, more immediate response requirement. The response requirements were fixed-interval schedules that did not lead to an immediate food reinforcer, but that interrupted a 55-s period in which food was delivered at random times. The experiments used an adjusting-delay procedure in which the delay to the start of one fixed-interval requirement was varied over trials to estimate an indifference point-a delay at which the two alternatives were chosen about equally often. Experiment 1 found that as the delay to a shorter fixed-interval requirement was increased, the adjusting delay to a longer fixed-interval requirement also increased, and the rate of increase depended on the duration of the longer fixed-interval requirement. Experiment 2 found a strong preference for a fixed delay of 10 s to the start of a fixed-interval requirement compared to a mixed delay of either 0 or 20 s. The results help to distinguish among different equations that might describe the decreasing effectiveness of a response requirement with increasing delay, and they suggest that delayed reinforcers and delayed response requirements have symmetrical but opposite effects on choice.

For several decades, choice has been the focus of considerable research by those who study operant behavior. This is not surprising, because the topics of choice and operant behavior are intimately intertwined. In everyday life, people can choose among a large, almost infinite set of operant behaviors, and they can choose not only which behaviors to perform, but under what conditions, at what rate, and for how long. Because choice is an essential part of human (and animal) life, it has been studied with great interest not only by behavioral psychologists, but also by decision theorists, economists, political scientists, biologists, and others. The research methods used in these different disciplines vary widely, and a review of all of the different methods for studying choice is well beyond the scope and purpose of this chapter. Instead, the chapter will focus on the techniques most frequently used in operant research—techniques that involve single-subject designs, that allow precise control of the reinforcement contingencies, and that produce (in most cases) large and clear effects on each subject’s behavior.

In two experiments with pigeons, a single variable-interval schedule assigned reinforcers to two response keys on a percentage basis. The percentage of reinforcers assigned to each key was changed every few sessions, and subjects' choice responses were recorded before and after each change. In Experiment 1, the overall rate of reinforcement was varied across conditions The pigeons' choice responses adapted more quickly to a change in the reinforcement percentages when the overall reinforcement rates were higher, but acquisition rates varied by only about a factor of 3, whereas reinforcement rates were varied by about a factor of 9. In Experiment 2, the reinforcement percentages changed about every 8 sessions in Phases 1 and 3, but every 1 or 2 sessions in Phase 2. Pigeons' choice responses adapted to a change in reinforcement percentages more quickly in Phase 2 than in Phases 1 and 3. The results from both experiments pose difficulties for several prominent models of transitional choice behaviour. The results suggest that each successive reinforcer has more impact on a subject's subsequent choice behaviour when the overall rate of reinforcement is lower and when the reinforcement contingencies have changed frequently in the recent past.