Color alternation learning in the pigeon under fixed-ratio schedules of reinforcement

Pigeons were trained on a non-spatial delayed alternation task in which the correct stimulus was that color not responded to on the preceding trial. Subjects required to emit either 15 or 30 pecks to the correct stimulus within a trial learned the task, those required to emit only one or five pecks did not. Also, alternation was learned more easily after an incorrect than after a correct trial. Later experiments showed that a minimum fixed-ratio value was required for successful color alternation to occur, even though no fixed-ratio requirement was necessary when a position cue was available. The mechanism of the fixed-ratio effects derived from the pigeons' tendency to repeat their response in the presence of the color reinforced on the last trial. Whereas subjects trained on larger fixed-ratios corrected this error tendency within a trial, subjects trained on smaller fixed ratios did not.     

Assessing child-rearing style in ecological settings: its relation to culture, social class, early age intervention and scholastic achievement

Middle- and lower-class black and white adolescents were observed interacting with their mothers during a discussion of seven child-rearing problems. Maternal references to a range of disciplinary measures were identified, analyzed, and related to the subjects' scholastic performances concurrently. A factor analysis of process measures confirmed earlier findings based on self-report data concerning parental disciplinary style. Low SES mothers who participated in an early-age intervention and upper middle-class mothers tended to be less punitive than those in the low SES untreated group. Black mothers were less permissive than those in the white group. Parental disciplinary style was found to be significantly related to school performance. The results are discussed in terms of the development of methodological procedures for interaction analysis in semi-structured, ecological research, for the evaluation of process variables in early-age intervention follow-ups and theory relating disciplinary style to intellectual development.     

Perception of a throwing action from point-light demonstrations

80 adults (40 men and 40 women) aged 18 to 25 yr. and 80 boys aged 14 to 15 yr. observed a throwing action presented in point-light form at a frontoparallel viewpoint either as a video film or computer simulation of the actor. The display consisted of the relative motion of the wrist, elbow, and shoulder joints of the throwing arm. Subjects were asked to report what they observed. The action was recognised immediately by 68% of all subjects, and this value increased to 90% with one more viewing of the demonstration. Response was virtually the same for both types of display, and there were no differences between adults and children. The results were similar to those from other studies from which researchers have concluded that kinematic information alone is sufficient to permit perception of fundamental patterns of movement.     

Effect of mouth opening on bite-force discrimination

The purpose of this study was to determine whether different extents of mouth opening affect normal subjects' (N = 24; 12 women, 12 men) ability to discriminate differences in their interincisor bite force. Three mouth openings were selected including 50, 70, and 90 percent of maximum opening for each subject. Bite force was measured using a specially designed strain gauge scale which permitted subjects to monitor visually when their biting force equalled a preset resistance. Resistance forces of 500 and 1000 gm. were selected as standards. The procedure involved the use of a modified method of constant stimuli in which each subject was presented with a series of paired resistance settings, one at a time--the first resistance setting being the standard and the second resistance was the comparator. This paired-comparisons procedure was continued until the subjects' difference limen (DL) value (the threshold of discrimination between two forces) could be established. An analysis of variance yielded no significant differences in subjects' ability to discriminate bite force as a function of mouth opening.     

Some types of conditioned inhibitors carry collateral excitatory associations

Two experiments using summation tests in conditioned suppression with rats examined whether conditioned inhibitors generated by five different conditioning procedures have an associative structure which includes collateral excitatory associations. The existence of collateral conditioned excitation was inferred from an increase in the amount of manifest conditioned inhibition after a conditioned inhibitory stimulus (CS-) extinction treatment. The five CS-s evaluated were differential, explicitly unpaired, conditional, backward, and trace. With abbreviated conditioning (Experiment 1), the differential and explicitly unpaired CS-s exhibited conditioned inhibitory properties; the conditional, backward, and trace CS-s did not. Repeated extinction presentations of the CS- in the absence of the unconditioned stimulus unmasked conditioned inhibition to the conditional, backward, and trace CS-s revealing moderate degrees of conditioned inhibition for all five CS-s. After more extensive conditioning (Experiment 2), the explicitly unpaired and conditional CS-s were strongly inhibitory and the differential and trace CS-s were moderately inhibitory. The backward CS- was not inhibitory. Repeated presentations of the CS- in extinction unmasked conditioned inhibition to trace and backward CS-s. All five CS-s were now nearly equally inhibitory. That the measured inhibitory power of backward, trace, and conditional (after few trials) CS-s can be modulated by a CS- extinction treatment suggests that they have similar associative structures and carry, in addition to inhibitory associations, collateral excitatory associations that mask the expression of conditioned inhibition.     

Tendency to display spontaneous incubation does not affect maternal responsiveness in the domestic hen

Induction of maternal behavior was performed in 63-week-old hens of the JV15 (or "Vedette") strain which had previously exhibited brief incubating phases during the preceding egg-laying period to discover if their maternal behavior differed from that induced in hens who had no previous record of incubating. The degree of maternal behavior exhibited showed large variation among individuals. However, hens with a history of one or more spontaneous, brief incubation bouts and hens without such histories showed similar responsiveness toward chicks and similar levels of general activity. In most of the subjects, the establishment of maternal behavior was accompanied by a significant long-term fall in the plasma levels of luteinizing hormone whereas the plasma levels of prolactin appeared to be unaffected.     

The Hopelessness Scale for Children: Psychometric properties with normal and emotionally disturbed adolescents

The psychometric properties of the Hopelessness Scale for Children (HSC) were evaluated with a sample of 834 normal adolescents and 93 adolescent suicide attempters. Factor analyses studies revealed two factors with both groups. Internal consistency with item-total score correlations were acceptable, while moderate test-retest reliability was found over a 10-week period with the normal sample. Support for the validity of the HSC was provided via studies with the suicide attempter group in which positive correlations with depression and depressive attributional style were found. Predicted differences between the suicide attempters, an outpatient psychiatric sample, and normal controls were also found. However, some items did not appear to discriminate suicide attempters from controls. Results are discussed in terms of the utility of the HSC with adolescents and adolescent suicide attempters and with regard to differences between child and adult samples in hopelessness.