Integrating velocity,time, and distance information: A developmental study

The development of understanding the relationships between velocity, time, and distance was investigated in three tasks. In each task, values of two dimensions were given, and 5-year-olds, 10-year-olds, and adults had to infer values of the third dimension. These inferences were made in all age groups. The integration rules were found to depend upon age and task. In the distance = time × velocity task, all age groups obeyed the normative multiplication rule. In the time = distance ÷ velocity task, the two older age groups obeyed the normative division rule, but the 5-year-olds shifted to a simpler subtraction rule. In the velocity = distance ÷ time task, which was the most difficult, the two older age groups simplified to use of a subtraction rule, and the 5-year-olds simplified even further to use of a distance-only rule. The knowledge level revealed for young children contrasts sharply with results from previous studies using Piagetian choice tasks, which apparently investigate selective attention to one dimension rather than conceptual understanding of relations.     

A characterization of stochastic independence by association,with an application to random utility theory

A characterization of stochastic independence in terms of association of random variables is given. The result is applied to yield a simple proof of the Sattath-Tversky inequality without continuity assumptions.     

Component processes of an overt rehearsal strategy in young children

The locus of facilitation due to rehearsal was investigated in three experiments with first-grade children. Several different overt acquisition strategies in a four-item sequential memory task were compared, including ordered repetition, item repetition, item labeling, and free strategy conditions. Experiment 1 showed that ordered repetition yields most of the facilitation due to rehearsal, and Experiment 2 demonstrated that the facilitation cannot be attributed to spaced practice. Experiment 3 showed that retrieval practice during study may improve memory performance but that the facilitation due to ordered repetition and retrieval practice is relatively short term. Mere repetition and labeling were not found to be significant component processes of rehearsal in any of the experiments. These results were discussed in terms of their relevance to rehearsal training studies and a differentiation between maintenance and elaborative rehearsal.     

Massed vs. spaced exposure sessions in the treatment of agoraphobia

The differential effects of massed and spaced sessions of exposure in vivo were investigated with 11 agoraphobics in a crossover design. Clients were randomly assigned to one of the following two groups: (a) 10 daily sessions followed by 10 weekly sessions, or (b) 10 once-weekly sessions followed by 10 daily sessions. The results indicated that both massed and spaced sessions of exposure in vivo effected changes in avoidance behavior and subjective anxiety of agoraphobics, massed practice being superior especially with respect to avoidance. It was suggested that the superiority of massed practice is due to the lack of opportunity to engage in avoidance or escape during short inter-session intervals. The relationship between subjective anxiety and avoidance were considered and the differences between clinical and statistical significance were discussed.     

Memory strategies used by young normal and retarded children in a directed forgetting paradigm

Two experiments were reported investigating the possibility that normal children (6- to 7-years old) and retarded children (9- to 10-years old) equated for immediate memory performance may not use effective strategies to eliminate interference from irrelevant information in memory. In both experiments a directed forgetting paradigm was used in which the children were presented with two sets of four pictures, and recalled only one set on each trial. On some trials, there was a cue to forget the first four and to remember only the last four pictures. In the first experiment both groups adopted a passive-active strategy in which the to-be-remembered items were processed actively only after a forget cue. Experiment 2 replicated this pattern of results. The use of sophisticated directed forgetting strategies seemed to be beyond the immediate abilities of these children. Two possible interpretations of the passive-active strategy were offered: (a) The strategy was an attempt to cope with the presence of occasionally irrelevant information and (b) The strategy was an attempt to cope with memory overload.     

Habituation during exposure treatment: Distraction vs attention-focusing

To investigate the effects of distraction and attention-focusing during in-vivo exposure to feared stimuli, the responses of 16 obsessive-compulsives with washing rituals were studied. A cross-over design was employed in which 6 of the subjects underwent exposure with attention focusing on the first day followed by exposure with distraction on the second day. The remaining subjects received the reverse order. Habituation of both heart rate and subjective anxiety was observed under both conditions, the rate of habituation tending to remain constant throughout the 90-min exposure. Greater between-session habituation and greater synchrony between the psychophysiological and the subjective measures of anxiety was observed when attention-focusing preceded distraction. Since habituation and synchrony have previously been found to be positively related to treatment outcome, the present results suggest that treatment by exposure to feared stimuli may be more effective if attention-focusing is promoted.     

Effects of imaginal exposure to feared disasters in obsessive-compulsive checkers

The combined effects of imaginal exposure to feared catastrophes and in vivo exposure to external stimuli were compared with the effects of in vivo exposure alone in 15 obsessive-compulsives with checking rituals. The first group received 90 min of uninterrupted exposure in imagination, which concentrated mainly on disastrous consequences, followed by 30 min of exposure in vivo to stimuli-situations which triggered rituals. The second group was given 2 hr of exposure in vivo only. Both groups were prevented from performing rituals. Treatment consisted of 10 daily sessions within a 2 week period.Assessments were conducted before and after treatment and at follow-up ranging from 3 months to 2.5 yr with a mean of 11 months. At post-treatment both groups improved considerably and did not differ. But at follow-up those who received imaginal and in vivo exposure maintained their gains, whereas the group who were treated by exposure in vivo alone evidenced partial relapse on four of the six dependent measures. The results tend to indicate that a closer match between a patient's internal fear model and the content of exposure enhances long term treatment efficacy.