The kinematics,movement phasing and timing of a skilled action in response to varying conditions of uncertainty

This study was designed to provide a detailed analysis of the parameters which interact to produce a field hockey drive. The drive was performed by an elite performer under two conditions of uncertainty (Blocked and Random). The subject was asked to drive a field hockey ball toward a specified target. In the Blocked condition the speed of the approaching ball remained constant (20, 30 and 40 m.p.h.) while in the Random condition these speeds were randomly assigned to each trial. Cine analysis of the subject's successful responses under the two experimental conditions led to an investigation of the kinematics, phasing, and timing of the stroke. The subject placed emphasis upon varying the initial phases of the stroke (i.e., backswing and preparatory phases) in order to produce a temporally consistent ballistic downswing to ball contact. It seemed likely that the subject appraised the ball speed that was being delivered and then incorporated additional stick movement to ‘mark time’ before initiating temporally consistent movement phases, as spatial uncertainty increased, the subject delayed her response initiation, but then tended to respond in intervals of one reaction time for each stroke phase. Consistency was evident for displacement and initiation point values, but to a lesser extent than existed for the other variables. However, as a result of this adjustment in spatial location and displacement of the stick end during the preliminary phases of the response, the subject was able to produce a consistent and accurate ballistic downswing.     

Similarity and contrast in memory for relations

The paper reports four experiments concerned with memory for sets of categorically related or unrelated nouns, as a function of the extent to which initial processing focused on categorical or distinctive features of the nouns. The general finding is that distinctive features are valuable for later intracategory discrimination in recall and recognition, but categorical features are not, as judged by cued recall, recognition, measures of association between items, and categorical intrusion errors. A theoretical framework, based on the diagnostic value of features for various classifications, is offered as an account of the results.     

Problem-oriented training promotes spontaneous analogical transfer: Memory-oriented training promotes memory for training

Spontaneous analogical transfer is the use of information from one problem to solve another problem, without an explicit hint to use the previous information. The results of five experiments were that if subjects tried to solve a training problem before hearing its solution, or tried to explain a training story's solution before hearing the correct explanation, spontaneous transfer was more likely than it was if subjects had studied the same training passage for memory before hearing its solution or explanation. The advantage of problem-oriented processing over memory-oriented processing occurred even though solution attempts nearly always failed, and the advantage was not reduced if the target problem was tested 15 min later rather than immediately after training. We propose that problem-oriented processes performed at study are appropriate processes to use at test. Further support for the account comes from subjects' memory for the training passages; the advantage for problem-oriented processing on solution tasks was mirrored by an equally substantial advantage for the memory-oriented subjects on a recall task.     

Consistency and error in motor performance

Two response measures that described the consistency and accuracy of motor performance were investigated. A pursuit tracking task was used as the vehicle whereby changes in perceptual motor performance could be monitored over several learning trials. The intra-individual variability of a subject's tracking response was compared to the root mean squared error that was accumulated during each block of trials. Whereas both response measures were sensitive to the changes in performance that occured as a result of practice, neither could be considered sufficiently informative as to be used as a sole indicator of skill acquisition. It appears that both consistency and error measures are needed to describe the subjects' performance as they acquire a perceptual motor skill.     

Expectancy of success on sex-linked tasks

College subjects undertook nine cognitive tasks with different perceived sex linkages, stating their expectancy of success prior to each task and attributing causality for their perceived performance following each task. As hypothesized, two components were present in the overall sex difference in expectancy of success, even when differences in actual task performance were statistically controlled. One component was attributable to a general tendency of females to state lower expectancies; the other was a function of the accord between the perceived sex linkage of the task and the subject's sex. The attribution data suggest that females tend to be more external for success and more internal for failure than males.The research reported here was partially supported by Grant #10692 from the Research Foundation of the City University of New York. The assistance of Bruce Eisman in testing subjects and of Rudy Lorber in data analysis is gratefully acknowledged.     

Crowding and stress: 2. A personal space approach

The concept of ‘personal space’ has sometimes been invoked in attempts to explain stressful effects of crowding; but the literature on personal space reveals divergent findings according to the definitions and methods of measurement used. Redefinitions are proposed whereby personal space preferences can be seen as mediating our reactions to the spatial proximity of others, according to a dynamic model which considers both task-related needs for physical space and privacy needs, together with concern over social norms and attributions. It is argued that perceived illegitimate invasion of the personal space one claims is likely to give rise to stress effects if coping responses fail. Thus crowding is likely to be stressful in many natural contexts where personal space is intruded upon frequently, especially when attributions of intentional thwarting are made. Further theoretical advances in this area must rest upon more precise specification of processes by which social relationships, situational variables, and subjective motivational, perceptual, and evaluative factors jointly determine an agent’s personal space claims and associated reactions to spatial invasion.