Consensus effects in categorization decisions

A previous study (Gilat et al., J. Exp. Psychol. Appl. 3 (1997) 83) has shown that the incentive to reach consensus can raise the tendency to rely on base rates in signal detection decisions and can reduce the probability that less likely events will be accurately classified. This phenomenon was named the “consensus effect”. The current study assesses the conditions under which this effect develops and in particular the effects of information about the game and of the incentive structure on the learning process. The results of three experiments show that the learning process slows when participants have information about the actual state of nature. This finding is captured by a reinforcement learning model with the assumption that information narrows the distribution of the initial propensities for choosing among cutoffs. The results are further evidence for the utility of the combination of learning models and analyses of cognitive processes for the prediction of decision making in situations involving multiple players.     

A quantitative interresponse-time analysis of DRL performance differentiates similar effects of the antidepressant desipramine and the novel anxiolytic gepirone.

We describe an interresponse-time analysis of performance on a differential-reinforcement-of-low-rate 72-s schedule. This analysis compares the obtained interresponse-time distribution of individual rats to a corresponding random interresponse-time distribution. The random interresponse-time distribution is a negative exponential probability function; it predicts the relative distribution of interresponse times if the rat emitted the same number of responses randomly (i.e., with a constant probability) with respect to time. The analysis provides quantitative measures of peak location and dispersion of the interresponse times toward random performance. In Experiment 1, an unexpected outcome of this analysis was that the rats would have obtained more reinforcers had they responded at the same rate but randomly. Based on the interresponse-time analysis in Experiment 1, it was shown that rats trained on the differential-reinforcement-of-low-rate 72-s schedule could increase the number of reinforcers obtained in two ways: first, by a coherent shift of the interresponse-time distribution toward longer durations and, second, by dispersal of the interresponse times toward a random interresponse-time distribution. Experiment 2 applied the analysis described in Experiment 1 to the effects of desipramine and gepirone. Both drugs decreased response rate and increased reinforcement rate, but their effects on the distribution of interresponse times were different. The increase in reinforcement rate observed with desipramine was accompanied by a coherent shift of the reinforcement rate observed with gepirone was accompanied by dispersal of the interresponse-time distribution toward the random negative exponential prediction.     

SOCIAL VALIDATION: THE EVOLUTION OF STANDARDS OF COMPETENCY FOR TARGET BEHAVIORS

The use of social validation procedures has become widespread in recent years. Although most researchers have used social validation procedures to select target behaviors and to evaluate whether the changes produced by a treatment program should be considered socially useful, little attention has been focused upon using the social validation process to determine the optimal levels for target behaviors. This paper suggests several ways in which social validation procedures can be employed in order to select when and how much to change target behaviors.     

Percentage reinforcement and choice

Pigeons responded on identical concurrent variable-interval schedules (choice phase), producing outcomes of either periodic reinforcement schedules always terminating in reinforcement (reliable schedule) or otherwise identical schedules providing reinforcement on only a percentage of instances (percentage reinforcement schedule). Comparisons of this type constituted two assessments of the generality of preference for percentage reinforcement reported by Kendall (1974). In a third set of conditions, a reliable schedule was pitted against a percentage reinforcement schedule in which the more negative outcome was a leaner schedule of reinforcement (rather than nonreinforcement, as in the other two conditions). In all three types of conditions, the schedule providing the higher rate of reinforcement was preferred. Results from a subsequent manipulation suggest that Kendall's contrasting results may have depended on the fact that the stimuli in his choice phase (unlit keys) were physically identical to the stimulus correlated with the nonchosen outcome in his outcome phase.     

Constituents of response rates

Response rate and the proportion of time pigeons allocated to a key-pecking activity were measured on several basic types of reinforcement schedules. Reinforcement frequency was varied within each type of basic schedule, and the effects on two constituents of response rate were noted. Propensity, the proportion of time the birds spent on a platform in front of the key, showed very consistent effects as reinforcement frequency varied: in general, it decreased when reinforcement frequency markedly decreased and it increased when reinforcement frequency increased. Speed, key pecks per unit of time spent on the platform, showed inconsistent effects when reinforcement frequency varied. Consequently, response rate showed less consistent effects than did propensity. Cumulative response records demonstrated the existence of several different types of transitions or boundary states between the key-pecking activity and other activities. The types of transitions that occurred between activities depended on both the type of reinforcement schedule and the frequency of reinforcement. The propensity data support the position that general laws of behavior can be based on temporal measures of behavior. The speed data suggest that, if a complete assessment of the dynamic properties of behavior is to be achieved, measures of behavior must incorporate the structural variations in the operant unit.     

Local response-rate constancy on concurrent variable-interval schedules of reinforcement

Concurrent variable-interval schedules were arranged with a main key that alternated in color and schedule assignment, along with a changeover key on which a small fixed ratio was required to changeover. Acceptable matching was observed with pigeons in two replications, but there was a tendency toward overmatching. Local response rates were found to differ for unequal schedules of a concurrent pair: local response rate was greater for the variable-interval schedule with the smaller average interreinforcement interval, but qualifications based on an interresponse-time analysis were discussed. In a second experiment, two 3-minute variable-interval schedules were arranged concurrently, and the experimental variable was the changeover procedure: either a changeover delay was incurred by each changeover or a small fixed ratio on a changeover key was required to complete a changeover. Changeover delays of 2 and 5 seconds were compared with a fixed-ratio changeover of five responses. The response output on the main key (associated with the variable-interval schedules) was greater when a changeover delay was arranged than when a fixed ratio was required to changeover. A detailed analysis of stripchart records showed that a 2-second delay generated an increased response rate for 3 seconds after a changeover, while the fixed-ratio requirement generated an increased rate during the first second only, followed by a depressed response rate for 2 seconds.     

Rarely Occurring Headaches and Rarely Occurring Blindness: Is Rarely=Rarely? The Meaning of Verbal Frequentistic Labels in Specific Medical Contexts

In three experimental studies, factors were examined which might influence the interpretation of verbal frequentistic labels in a specific context (i.e. side effects of medical drugs). In Study 1, we directly assessed subjects' numerical equivalents of three verbal labels (recommended for use by the German Federal Health Agency), which were embedded in stylized leaflets for medical drugs; we compared the estimates with those obtained in a context-free situation. The major findings were that (1) subjects' numerical equivalents for the verbal labels were clearly lower in the context condition than in the context-free situation, (2) subjects'; interpretations appeared to depend on the seriousness of the side effects, but (3) this dependency disappeared when explicit base rates were provided. In Studies 2 and 3, we indirectly examined the influence of the seriousness of the side effects, their frequency, and of the mode of expression (verbally versus numerically) by asking for risk judgments for and choices between drugs. Results of particular importance were that (1) seriousness and frequency of side effects had the same influence on judgments and choices but the mode of expression had no significant effect on either judgments or choices; (2) when subjects’ individual numerical equivalents of verbal labels were used in the leaflets, numerically described drugs were judged equally risky as verbally described drugs but were significantly preferred for consumption. These findings have theoretical relevance for research on the processing of verbal and numerical frequentistic expressions as well as a number of practical implications for the communication of medical information.     

降压治疗的决策思考

尽管降压药物有了很大发展,高血压的控制率仍很低下。降压治疗中还存在包括医生和患者两方面的许多误区。目前已取得的共识是:降压治疗的益处主要来自血压控制。因此,非常重要的是要达到血压的有效和长期稳定的降低。根据患者的年龄、基线血压、伴随的临床状况等,因人而异地选择副作用小、降压效果好的药物,提高顺应性是改善高血压控制率的关键。     

After-School Supervision, Psychosocial Impact, and Adolescent Smoking and Alcohol Use in China

We examined effects of self-care after school hours and psychosocial factors on cigarette smoking and alcohol use among adolescents in China. Survey data were obtained from 4734 7th and 11th grade students from seven cities across China. Students were queried about the frequency and quantity of unsupervised self-care after school in an average week. Tobacco and alcohol usage were also obtained. Odds ratios were calculated to determine the strength of association between unsupervised self-care after school and substance use. Results indicated that the amount of self-care after-school (how many days and how many hours per week) was significantly associated with increased risk for smoking and alcohol use among Chinese adolescents. These associations remained significant even after controlling for anxiety, depressive symptoms, and peer influence. The interaction between unsupervised self-care after school and peer influence indicated that unsupervised self-care after school is a stronger risk factor for smoking among adolescents with pro-smoking friends. The findings suggest that substance use prevention programs for youth in China should try to enhance parental monitoring. As it may not be feasible for families to revert to a lifestyle that includes supervision by relatives, other approaches such as organized after-school care are worthy of consideration.     

Heart Rate Variability and Sustained Attention in ADHD Children

The major goal of the current study was to investigate the association between continuous performance tests (CPTs) and the heart rate variability (HRV) of attention deficit hyperactivity disorder (ADHD) children. The HRV, specifically the 0.10-Hz component, may be considered to be a psychophysiological index of effort allocation (motivation): The less effort the subject allocates, the greater the 0.10-Hz component. Results indicated that, compared to controls, ADHD subjects had a greater 0.10-Hz component, which was associated with poor test performance over time. Thus, using a psychophysiological measure, we were able to confirm the clinical concept of ADHD from a motivational perspective.