Residence time and choice in concurrent foraging schedules

Five pigeons were trained on a concurrent-schedule analogue of the “some patches are empty” procedure. Two concurrently available alternatives were arranged on a single response key and were signaled by red and green keylights. A subject could travel between these alternatives by responding on a second yellow “switching” key. Following a changeover to a patch, there was a probability (p) that a single reinforcer would be available on that alternative for a response after a time determined by the value of λ, a probability of reinforcement per second. The overall scheduling of reinforcers on the two alternatives was arranged nonindependently, and the available alternative was switched after each reinforcer. In Part 1 of the experiment, the probabilities of reinforcement, ρ_red and ρ_green, were equal on the two alternatives, and the arranged arrival rates of reinforcers, λ_red and λ_green, were varied across conditions. In Part 2, the reinforcer arrival times were arranged to be equal, and the reinforcer probabilities were varied across conditions. In Part 3, both parameters were varied. The results replicated those seen in studies that have investigated time allocation in a single patch: Both response and time allocation to an alternative increased with decreasing values of λ and with increasing values of ρ, and residence times were consistently greater than those that would maximize obtained reinforcer rates. Furthermore, both response- and time-allocation ratios undermatched mean reinforcer-arrival time and reinforcer-frequency ratios.     

Features Resembling Tourette''s Syndrome in Developmental Stutterers

Developmental stuttering (DS) may be related to the extrapyramidal motor system and shares many clinical similarities with Tourette's syndrome (TS), which is widely believed to be associated with extrapyramidal dysfunction. Twenty-two stutterers were examined for neuropsychiatric features commonly seen in TS, including tics, obsessive-compulsive behaviors (OCB), and attention deficit disorders. Eleven stutterers displayed motor tics, and symptoms of OCB were observed at rates similar to those seen in persons with TS. Few stutterers demonstrated significant attentional deficits. Findings are consistent with models suggesting extrapyramidal involvement in DS and raise the possibility that DS and TS are pathogenetically related.     

A Playroom Observation Procedure to Assess Children with Mental Retardation and ADHD

Forty-two children (ages 6 to 12 years old) with moderate mental retardation to borderline intellectual functioning were studied in a laboratory playroom setting to determine whether children identified as ADHD (attention deficit hyperactivity disorder) or controls differed on activity and attentional measures. Children with ADHD were further divided into ADHD + conduct problems (ADHD + CD) and ADHD-only subgroups (with an ADHD-combined group comprising children of both subgroups). An interval recording system was used to code observations of independent play and a restricted academic task. Results indicated that the ADHD-combined group was significantly more vocal and engaged in a significantly greater number of toy changes than controls during independent play. Significant group differences were also noted during the restricted academic task, with the ADHD-combined and ADHD + CD groups more off-task and engaging in a greater number of toy touches than controls. Discriminant analyses found independent play measures to predict group membership in 70 percent of cases (ADHD-combined vs. controls), but in only 64 percent of cases using measures from the restricted academic task. No significant findings resulted when the ADHD subjects were further divided into two subgroups. Despite some inconsistent findings, such laboratory-based observations may be of value in the diagnosis of ADHD in children with moderate mental retardation to borderline intellectual functioning.     

The Hairlessness Norm: The Removal of Body Hair in Women

This study aimed to investigate the frequency andmeaning of the removal of body hair in women.Participants were 129 female university students (meanage = 22.3 years) and 137 female high school students (mean age = 14.3 years). Almost all (>95%)were Caucasian. It was found that, as predicted, the vastmajority (92%) of women remove their leg and/or underarmhair, most frequently by shaving. This was irrespective of their feminist beliefs, but wasnegatively related to self-esteem in university students.The reasons cited for hair removal were primarilyconcerned with a desire for femininity andattractiveness. However, the reasons provided for starting toremove body hair differed between the groups, in thatthey were relatively more normative for the universitystudents than for the high school students. It was concluded that women's stated reasons forstarting the practice of hair removal reflectprimarilytheir vantage point as an observer. In fact, removingbody hair is a practice so normative as to go mostly unremarked, but one which contributessubstantially to the notion that womens' bodies areunacceptable as they are.     

SOCIAL REACTIONS, COPING STRATEGIES, AND SELF-BLAME ATTRIBUTIONS IN ADJUSTMENT TO SEXUAL ASSAULT

The present study investigated the impact of social reactions of others to sexual-assault victims on disclosure of their victimization. A convenience sample of adult sexual-assault victims (N = 155) completed a mail survey in which they reported information about their sexual assaults and postassault experiences. As expected, all negative social reactions were strongly associated with increased psychological symptoms, whereas most positive social reactions were unrelated to adjustment. The only social reactions related to better adjustment were being believed and being listened to by others. Victims experiencing negative social reactions also reported poorer adjustment even when other variables known to affect psychological recovery were controlled. Avoidance coping mediated the association of negative social reactions with adjustment. Implications of these findings for research and treatment of sexual-assault survivors are discussed.     

Black-white personality differences: another look.

Investigated the meaning of Black-White differences typically discovered on personality instruments by administering a pool of items derived from both the MMPI and California Psychological Inventory, as well as a group form of the Embedded Figures Test, to a sample of 226 black and white junior college students. A cluster analysis of the unexpectedly large number of inventory items significantly differentiating the two races produced reliable and meaningful configurations. Interpretations of race differences on these clusters and the EFT provide a new perspective on the meaning of Black-White personality differences.     

Sequential precession and diminishing returns in the acquisition of a motor skill

As students progress to higher and higher levels in the acquisition of a skill their number gets smaller and smaller. This article concerns the average length of time it takes the members of these successively smaller groups to complete earlier stages of skill acquisition. In the data presented, which concern Red Cross swimming, the more advanced a group is the less time its members take on the average to complete a preceding stage (sequential precession). The discussion section brings out a second relation in the same data: Namely, the further the same students advance in skill acquisition the smaller the advantage they enjoy over other students at the same level (diminishing returns).     

Semantic differential studies of children's language development: Some methodological problems

A semantic differential study of development of antonym meanings revealed methodological problems (e.g., concept-scale interaction and developmental changes in scale-checking style) not fully considered in previous semantic differential investigations of child language development. Twenty adjectives were rated on 10 scales by subjects from grades K to 5 (approximately 6 through 11 years old) and adults. Analyses by means, polarity ratings, and average sums of squared differences failed to yield consistent developmental trends. Subjects' choices of scale ratings did show clear age-related differences: Grades K and 1 chose extreme ratings almost exclusively; grades 2 through 4 showed an increase in neutral choices and decreases in extreme ratings; grades 4 and 5 and adults chose extreme ratings least often, neutral choices most often, and more intermediate ratings than any younger subjects. Results show that scale choice is a crucial factor in designing semantic differential studies with children, there is a low correlation between mean scores and ratings given by individual children, and shifts in scale-checking style should be considered when interpreting apparent developmental changes in children's semantic differential ratings.