Choice between reliable and unreliable outcomes: mixed percentage-reinforcement in concurrent chains.

Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent-chains procedure. In Experiment 1, the alternatives were terminal-link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing, reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay-reduction hypothesis to choice procedures involving mixed schedules of percentage reinforcement.     

Postnatal development of respiratory and vocal responses during aversive classical conditioning in cats

Respiratory rate, respiration amplitude, and vocal responses were recorded in cats of different ages during classic conditioning. Vocal responses to the conditional stimulus (CS) appeared first in 8-week-old kittens, and became prominent at older ages. An increase in respiration rate occurred after the onset of the CS in cats of all ages. Similarly, the decrease of respiration amplitude was observed at all ages, but only in 8-week-old and older subjects did this response resemble an adult pattern. In 4-week-old kittens the response was characterized by an early and brief peak, suggesting an alpha conditional response (CR). Clear and significant discrimination between a warning and a safety signal was present in both respiratory and vocal responses after the age of 8 weeks.     

Reading-disabled hyperactive children: A distinct subgroup of Attention Deficit Disorder with Hyperactivity?

Mixed hyperactive/reading-disabled children, selected from a large sample of hyperactive children, were compared to pure hyperactive children on demographic, behavioral, and neuropsychological measures. Children in the Mixed group were reading-disabled relative to age and IQ; those in the Pure group had achievement scores that were average relative to age and IQ. The Mixed group was significantly older than the Pure group; there were no differences in gender, race, or socioeconomic status. Behaviorally, the groups did not differ significantly on teacher ratings or on psychiatric ratings of aggression. The Mixed group had a significantly higher Performance IQ, whereas the Pure group had a significantly higher Verbal IQ and performed better on measures of cognitive impulsivity. Several other measures failed to distinguish the groups. The data give minimal support to the notion that pure hyperactive and mixed hyperative/reading-disabled children constitute distinct subgroups of Attention Deficit Disorder with Hyperactivity.This research was supported in part by Mental Health Clinical Research Grant MH-30906 and by U. S. Public Health Service Grant MH-18579.     

Discriminating between alcoholic and nonalcoholic blacks and whites on the MMPI

The purpose of the present study was to investigate the influence of race (black, white) on the MMPI performance of alcoholic and nonalcoholic inpatients. Subjects were 73 (27 black, 46 white) male alcoholic inpatients and 73 (27 black, 46 white) male nonalcoholic psychiatric inpatients. While black and white alcoholics failed to differ on the MMPI, white alcoholics presented as less disturbed and black alcoholics as less defensive and distressed, compared to their respective nonalcoholic counterparts. Furthermore, only white alcoholics were accurately identified by the MMPI 2-4/4-2 high-point pair combination and only white alcoholics achieved more high-point pairs containing Scale 4 relative to nonalcoholic controls.     

Children's expectations of sex differences in parents' responses to sons and daughters encountering interpersonal problems

The present study examined 8-12-year-old children's perceptions of parents' responses to sons and daughters experiencing interpersonal conflicts. In general, the children expected parents to respond in a manner consistent with traditional instrumental-expressive sex-role stereotypes. The implication of these findings for inadequacies in the socialization of interpersonal problem-solving styles in boys and girls is discussed.     

Process and content in an outpatient schizophrenic group

Process and content issues were evaluated during the first six months of an outpatient schizophrenic group. Compared with groups composed of neurotic and characterological patients, the schizophrenic group scored higher in the Avoiding dimension of the Group Climate Questionnaire (GCQ-S). There was more cohesion and less interpersonal conflict as time went on. Although topics related to engagement and differentiation were discussed, there was no obvious GCQ-S evidence of these first two stages of group development. However, the data supported the presence of stage 3 (individuation) during sessions 20–26. Interpersonal topics dominated the group discussions, followed by issues involving reality-testing, expression of emotions, and advice-giving.The authors wish to thank Dr. K. Roy MacKenzie for his helpful comments on a draft of this paper.     

Social science involvement in voir dire: Preliminary data on the effectiveness of “scientific jury selection”

The validity of what has been termed “scientific” or “systematic” jury selection (SJS) techniques is addressed using data from two actual cases; one criminal and one civil. Data from the highly publicized Joan Little trial indicated that where validity data were available for the survey approach and in-court rating of authoritarianism, these techniques measured what they purported to measure. Validation data were not available for a third technique—in-court rating of nonverbal communication. Data from the civil case indicated that the survey approach could successfully predict verdicts of mock jurors. It is concluded that while these data are suggestive of the validity of two of the techniques used in SJS, more rigorous tests are essential before conclusions can be drawn.