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.     

Repression-sensitization and emotion control

The internal structure of the Repression-Sensitization (R-S) Scale was examined by means of factor analysis. Following a scree test, four factors were extracted: lassitude/depression, extraversion/confidence, guilelessness/trust, and emotional lability. Concurrent validation using the Emotion Control Questionnaire and the Eysenck Personality Inventory showed that the factors extracted from the R-S Scale were related in predictable ways to existing personality constructs, but the results argue against the use of the overall R-S score as an index of emotional response style.     

The role of action-initiation in young children's causal explanations of action

Four studies examined preschoolers' use of the cue of action initiation to infer another's desired goal. In two studies, children watched as one protagonist self-initiated movement to a target while a second person was propelled there by an external force. Older 3-year-olds (M = 3;10) and 5-year-olds consistently judged only the self-initiated actor's movement as desire based. In the second study, however, younger 3-year-olds (M = 3;3 also participated, and they were equally likely to say that either movement was goal directed, even when the passive mover appeared to resist movement toward the goal. A third study, featuring only one protagonist, yielded no improvement among younger 3-year-olds. A fourth study emphasizing the single protagonist's persistence in approaching a target via repeated self-initiated movements revealed some improvement among younger 3-year-olds; older 3-year-olds were near ceiling performance. Altogether, these results suggest that differences in action initiation play an increasingly important role in 3-year-olds' mentalistic explanations of action. This development may be related to other critical changes occurring in 3-year-olds' developing theory of mind.     

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).     

Augmentation of in vivo exposure treatment for agoraphobia by the formation of neighbourhood self-help groups

The advantages of selecting agoraphobic patients for treatment by group exposure according to their residential geographic neighbourhood were evaluated in terms of facilitation of ‘homework’ practice and increased social contact. Both ‘zoned’ and ‘unzoned’ groups showed gains in ability to perform hierarchy items after 11 sessions of exposure, relative to a no-treatment control group. However only zoned subjects showed significant reductions in experienced anxiety when executing such items. Self-ratings of overall phobic severity also suggested a zoned group was superior to unzoned while assessors' ratings indicated both groups as equally improved. Only zoned subjects showed a significant increase in social range. Improvements were maintained at 3-months follow-up. No effect of treatment was found on either the Zung measure of anxious mood or on social integration.These results suggest that, where practical, zoning might offer the means for desirable continuation of intensive clinic-based group treatment as well as the benefit of extending treatment into the patients' environment as in home-based treatments. Crucial levels of group cohesion might also be increased although therapists should be prepared to negotiate resistance to a socially demanding programme from patients with significant additional social phobias.