Interruptions improve choice performance in gray jays: prolonged information processing versus minimization of costly errors

Under the assumption that selection favors minimization of costly errors, erroneous choice may be common when its fitness cost is low. According to an adaptive-choice model, this cost depends on the rate at which an animal encounters the choice: the higher this rate, the smaller the cost of choosing a less valuable option. Errors should thus be more common when interruptions to foraging are shorter. A previous experiment supported this prediction: gray jays, Perisoreus canadensis, were more error prone when subjected to shorter delays to access to food rewards. This pattern, though, is also predicted by an attentional-constraints model. Because the subjects were able to inspect the rewards during delays, their improved performance when subjected to longer delays could have been a byproduct of the experimentally prolonged opportunity for information processing. To evaluate this possibility, a follow-up experiment manipulated both delay to access and whether rewards could be inspected during delays. Depriving jays of the opportunity to inspect rewards (using opaque lids) induced only a small, nonsignificant increase in error rate. This effect was independent of length of delay and so the jays' improved performance when subjected to longer delays was not simply a byproduct of prolonged information processing. More definitively, even when the jays were prevented from inspecting rewards during delays, their performance improved when subjected to longer delays. The findings are thus consistent with the adaptive-choice model. Electronic Publication     

Post-decision consolidation: group members in different social settings compared to individual decision makers

Two experiments were conducted to examine how making decisions in a 3-member group affects the degree of post-decision consolidation, defined as attractiveness changes in favor of the chosen alternative. Both experiments were conducted in two sessions one week apart. In the first session (decision phase), participants estimated the importance of each of four different attributes describing two decision alternatives. They were then shown predetermined attractiveness ratings on each of the attributes and were to decide on the two alternatives, either individually or as a group. In the second session (post-decision phase), the participants were to attempt to recall the attractiveness ratings for the attributes as presented to them in session one. In both experiments, significant post-decision consolidation was found for individual decision makers but not for group members. In experiment 2, this result was replicated, no difference in consolidation being found between group members with face-to-face interaction and without.     

Individual postdecision processes in group settings

In two experiments Differentiation and Consolidation Theory (Diff Con) (Svenson, 1992) was used to investigate individual postdecision making processes in three-member groups. It was predicted that in groups in which the subjects preferred different alternatives (conflict groups), subjects would consolidate their own preferred alternative, and not the group's final decision. A second hypothesis was that no consolidation would be indicated in groups in which all members preferred the same alternative (non-conflict groups). The results showed that in conflict groups, the members who gave up their preferred alternative (minority members) consolidated their own preference, thereby significantly regretting the group decision. In contrast, members who got their own will through in the majority decision (majority members) showed no consolidation of the group decision. The corresponding pattern of results was replicated in a second experiment, using a different decision situation. The results indicated that perceptions of social support, agreement in a group and decreasing responsibility for a group's decision, could all partly substitute consolidation by attractiveness restructuring.     

Postdecision consolidation in a trend prediction task

To be able to learn from experience it is necessary to correctly apprehend experienced feedback and the situation in which it is provided. The results indicate how post-decision consolidation in complex domains may affect learning. The problem may be particularly pertinent in recurrent decision making where considerable risk is involved. The study explores the changes in aspect (signal) importance from pre- to postdiction as a function of outcome information. By postdiction we mean the remembering of an earlier prediction (cf. Hawkins & Hastie, 1990). Subjects were asked to decide on which of four alternative future price developments would follow a historical price trajectory for different commodities, and to rate the importance of each of the chosen alternative's corresponding aspects. The subjects revealed a bias in their support ratings of aspects--seeing support in aspects that traditionally (by themselves and in many contexts) would be seen as neutral or even counter-indicative of the alternative chosen. After an intermission, the subjects were also given information about what was indicated to be the actual development of the market. One group was told that their decisions were correct (irrespective of what the decisions were), another group that they were incorrect but close, a third group that they were incorrect by far, while a fourth group served as a control. Following this information the subjects were again asked to judge the importance of the aspects for their own prior decision on the most likely future development. The results indicated that outcome feed-back had an effect on post decision restructuring of facts. Subjects in the correct condition showed an average consolidation that increased the support, while the wrong conditions lead to negative consolidation (in retrospect indicating that they never found as much support for their decision in the past as they actually did). Thus, in a choice between consolidating their own initial prediction and the price trajectory they would have to live with, the decision makers consolidated the outcome. Therefore, the results of the study were related to the hindsight bias phenomenon (Fischhoff, 1975) and to Kahneman and Miller's (1986) mutability concept.     

Treatment of covert food stealing in an individual with Prader-Willi syndrome

Covert food stealing is common among individuals with Prader-Willi syndrome. We found that verbal reprimands, delivered contingent upon eating prohibited foods, were sufficient to decrease the food stealing of a girl with Prader-Willi syndrome. Warning stimuli were then used to help her discriminate between permitted and prohibited foods during sessions in which food stealing was not directly observed. This procedure resulted in decreases in food stealing from containers labeled with the warning stimuli.     

Testing the ability of children with attention deficit hyperactivity disorder to accurately report the effects of medication on their behavior

Children with attention deficit hyperactivity disorder (ADHD) are often treated with central nervous system stimulants, making the evaluation of medication effects an important topic for applied behavior analysts. Because assessment protocols emphasize informant reports and direct observations of child behavior, little is known about the extent to which children themselves can accurately report medication effects. Double-blind placebo-controlled procedures were used to examine whether 6 children with ADHD could recognize the effects of their medication. The children were given math worksheets to complete for 15 min during each of 14 sessions while on medication and placebo. Children completed a self-evaluation form at the end of each session, and ratings were compared to observed behavior and academic performance. Results indicated that 3 children were able to accurately report their medication status at levels greater than chance, whereas the accuracy of reports by all children was related to dosage level, differences in behavior, and the presence of adverse effects. The implications of these results for placebo-controlled research, self-monitoring of dosage levels, and accuracy training are discussed.     

Progressive-ratio schedules: effects of later schedule requirements on earlier performances

Four rats were studied with variants of a progressive-ratio schedule with a step size of 6 in which different terminal components followed completion of the 20th ratio: (a) a reversal of the progression, (b) a fixed-ratio 6 schedule, or (c) extinction. Responding in the progressive-ratio components of these schedules was compared to performances under conventional progressive-ratio baselines. Under baseline conditions, postreinforcement pauses increased exponentially as a function of increasing ratio size, whereas running rates showed modest declines. The procedure of linking the progressive-ratio schedule to the reversed progression or to the fixed-ratio component resulted in decreased pausing. Linking the progressive-ratio schedule to the extinction component had the opposite effect, that of producing weakened progressive-ratio performances as evidenced by increased pausing. Subjects whose responses were reinforced on half of the ratios also showed exponential increases; however, pauses were substantially shorter following ratios on which the reinforcer was omitted. The results suggested that progressive-ratio pausing reflects the influence of remote as well as local contingencies.     

Timeout postponement without increased reinforcement frequency

Three experiments were conducted to examine pigeons' postponement of signaled extinction periods (timeouts) from a schedule of food reinforcement when such responding neither decreased overall timeout frequency nor increased the overall frequency of food reinforcement. A discrete-trial procedure was used in which a response during the first 5 s of a trial postponed an otherwise immediate 60-s timeout to a later part of that same trial but had no effect on whether the timeout occurred. During time-in periods, responses on a second key produced food according to a random-interval 20-s schedule. In Experiment 1, the response-timeout interval was 45 s under postponement conditions and 0 s under extinction conditions (responses were ineffective in postponing timeouts). The percentage of trials with a response was consistently high when the timeout-postponement contingency was in effect and decreased to low levels when it was discontinued under extinction conditions. In Experiment 2, the response-timeout interval was also 45 s but postponement responses increased the duration of the timeout, which varied from 60 s to 105 s across conditions. Postponement responding was maintained, generally at high levels, at all timeout durations, despite sometimes large decreases in the overall frequency of food reinforcement. In Experiment 3, timeout duration was held constant at 60 s while the response-timeout interval was varied systematically across conditions from 0 s to 45 s. Postponement responding was maintained under all conditions in which the response-timeout interval exceeded 0 s (the timeout interval in the absence of a response). In some conditions of Experiment 3, which were designed to control for the immediacy of food reinforcement and food-correlated (time-in) stimuli, responding postponed timeout but the timeout was delayed whether a response occurred or not. Responding was maintained for 2 of 3 subjects, suggesting that behavior was negatively reinforced by timeout postponement rather than positively reinforced by the more immediate presentation of food or food-correlated (time-in) stimuli.     

Diagnosing agoraphobia in the context of panic disorder: examining the effect of DSM-IV criteria on diagnostic decision-making

A diagnostic and statistical manual (DSM)-IV diagnosis of agoraphobia in the context of panic disorder (PD) is based on three nosologically sufficient criteria: (1) avoidance, (2) use of companions, and (3) endurance of situations despite distress. Therefore, an agoraphobia diagnosis can be made across an extremely broad range of cases including when there are no avoidance behaviors (e.g., the patient endures the situation). It was hypothesized that clinicians do not weight these criteria equally and that the DSMs individual, sufficient criteria lead to poor inter-rater reliability. Clinicians (N=48) rated hypothetical patients with symptom profiles emphasizing each of these three criteria. Consistent with expectation, clinicians differentially weighted these criteria. Avoidance was relatively more apt to produce a diagnosis when only one criterion was emphasized in clinical vignettes. Inter-rater reliability was poor in instances when only one sufficient criterion was highlighted. Knowledge concerning DSM criteria resulted in a greater rate of agoraphobia endorsement, but knowledge did not account for the overall pattern of findings.     

An evaluation of a brief multiple-stimulus preference assessment with adolescents with emotional-behavioral disorders in an educational setting

Brief multiple-stimulus-without-replacement (MSWO) preference assessments were conducted with 3 adolescent boys with emotional-behavioral disorders in the context of their public school educational program. The reinforcing effects of stimuli identified as high, medium, and low preference were then evaluated using an alternating treatments design in which, following an initial baseline, stimuli were delivered contingent on on-task behavior. High-preference stimuli produced the highest percentages of on-task behavior for all 3 participants.