The micro-structure of tapping movements in children

In order to investigate the development of movement speed in relation to movement organization, children of 5, 6, 7, 8 and 9 years of age and adults carried out a reciprocal tapping task, in which time pressure and distance were manipulated. The duration, velocity, acceleration and accuracy of the movements were compared between age groups. Age differences appeared mainly in the homing time, not in the duration of the distance covering movement phase. Accuracy and velocity of the distance covering movement phase differed with age. Time pressure affected the homing time, but not the duration of the distance covering phase. Distance manipulation affected mainly the velocity and duration of the distance covering movement phase and the homing time. In the discussion it is contended that age differences in homing time may be related to both the accuracy of the distance covering movement phase and the rate of information processing of the subject.     

Rapid error correction during human arm movements: evidence for central monitoring

Studies were made of rapid error correction movements in eight subjects performing a visually guided tracking task involving flexion-extension movements about the elbow. Subjects were required to minimize reaction times in this two-choice task. Errors in initial movement direction occurred in about 3% of the trials. Error correction times (time from initiation to reversal of movement in incorrect direction) ranged from 30-150 ms. The first sing of correction of the error movement was a suppression of the electromyographic (EMG) activity in the muscle producing the error movement. This suppression started as early as 20-40 ms after the initiation of the error-related EMG activity and as much as 50 ms before any overt sign of limb movement. The correction of the error movement was also accompanied by an increase in the drive to the muscle which moved the arm in the correct direction. This increased activity always occurred after the initiation of the error movement. it is concluded that the first step in the error correction, suppression of drive to the muscle producing the error movement, cannot be based on information from the moving limb. It is thus suggested that this earliest response to the error movement is based on central monitoring of the commands for movement.     

A maximum likelihood hierarchical disaggregate model for predicting choices of individuals

The absence of operational disaggregate lexicographic decision models and Tversky's observation that choice behavior is often inconsistent, hierarchical, and context dependent motivate the development of a maximum likelihood hierarchical (MLH) choice model. This new disaggregate choice model requires few assumptions and accommodates the three aspects of choice behavior noted by A. Tversky (1972, Journal of Mathematical Psychology, 9, 341–367). The model has its foundation in a prototype model developed by the authors. Unlike the deterministic prototype, however, MLH is a probabilistic model which generates maximum likelihood estimators of the aggregate “cutoff values.” The model is formulated as a concave programming problem whose solutions are therefore globally optimal. Finally, the model is applied to data from three separate studies where it is demonstrated to have superior performance over the prototype model in its predictive performance.     

Children's understanding of conversational principles

Sixteen preschool, first-, and third-grade children were presented with short stories ending with a verbal statement by a story character. Two alternative ending statements were provided. One alternative violated a postulate (H. P. Grice, 1975, in P. Cole & J. Morgan (Eds.), Syntax and Semantics (Vol. 3), New York: Academic Press) or a reasonable request condition (D. Gordon & G. Lakoff, 1971, Conversational postulates, papers from the seventh regional meeting of the Chicago Linguistic Society, University of Chicago, Department of Linguistics), while the other alternative did not. The child's task was to choose the “funny or silly“ ending, i.e., the violation. Data analysis showed that 100% of the third-graders, 83% of the first-graders, and 19% of the preschoolers performed with significant (P < .02) accuracy. These results suggest that children's understanding of conversational principles improves considerably between preschool and first grade. There were no significant differences among four types of conversational principles examined.     

A process analysis of the effects of performance-contingent rewards on intrinsic motivation

In this study, the effects of performance-contingent rewards on intrinsic motivation were examined in comparison to no-reward controls receiving identical performance feedback. A path analytic process analysis was conducted to examine the mediation of reward effects on subsequent task interest. It was hypothesized that competence valuation, or the personal importance of doing well, would be an important mediator of interest in situations where performance feedback was available. Rewards were predicted to affect interest by influencing an individual's valuation of competence, and by altering the competence valuation mediation process. In addition, achievement orientation was hypothesized to interact with reward in affecting importance and the mediation process. Prior to performing an interesting puzzle, high school students were offered a performance-contingent reward, and then indicated how personally important it was to do well. After doing three puzzles, all subjects received positive feedback regarding their performance. Multiple regression analyses indicated that importance was affected by the experimental variables, and had a positive causal impact on subsequent intrinsic motivation. It was found that the promise of performance-contingent reward positively affected importance for low achievers relative to high achievers, and that the mediation of subsequent intrinsic interest by importance differed according to reward by achievement combinations. Additionally, a direct effect revealed that performance-contingent rewards significantly enhanced interest, relative to no-reward controls receiving identical performance feedback.     

Intergroup contact: The typical member and the exception to the rule

Three studies examined the role of the perceived typicalness of an out-group member on her effectiveness in improving evaluations of her group. Subjects were students at two adjacent colleges. In the first study they interacted with a member of the out-group college. The interaction was either pleasant or unpleasant, and the contact person either confirmed or disconfirmed several stereotypes of the out-group (typicalness manipulation). Subjects evaluated the out-group most favorably when they interacted with the typical-pleasant member of the out-group. The second study demonstrated that contact with a highly typical member is not beneficial if her typicalness is based on stereotypes that reflect negatively on the subject's in-group. Several explanations of the typicalness findings were considered in a third study. Support was found for the hypothesis that the more typical member is perceived to be more predictive of the personality and actions of other out-group members.     

Context effects on the perceived physical attractiveness of faces

Four experiments were conducted to study the nature of context effects on the perceived physical attractiveness of faces. In Experiment 1, photos of faces scaled on attractiveness were presented in sets of three, with target faces appearing in the middle flanked by two context faces. The target faces were of average attractiveness, with the context faces being either high, average, or low in attractiveness. The effect of the context was one of assimilation, rather than contrast, regardless of whether the persons in the photos were portrayed to be associated. This result was interpreted in terms of a “generalized halo effect” for judgments of the physical attractiveness of stimuli within a group. Presenting the persons of a set as friends enhanced the perceived attractiveness of the target face but only when the context did not contain a face of low attractiveness. In Experiment 2, the assimilation effect was observed to carry over to influence ratings of the target faces several minutes after the context faces had been removed. Experiment 3 showed the assimilation effect to be robust regardless of whether the context was composed of two faces or one, but Experiment 4 showed the assimilation effect to be evident only when the context faces were presented simultaneously with the target.     

Self-efficacy,nicotine-fading/self-monitoring and cigarette-smoking behaviour

An attempt to replicate and extend the successful results of Foxx and Brown's (1979) nicotine-fading, self-monitoring procedure for smoking abstinence or controlled smoking was undertaken using a combination of their procedure and cognitive-behavioural interventions. The latter consisted of: (1) a variation of Meichenbaum's (1977) self-instructional training and (2) a simple, direct manipulation of Bandura's (1977) concept of self-efficacy. Evidence was found to support Foxx and Brown's (1979) procedure with respect to reduced smoking rate and nicotine/tar intake. Combinations of treatments did not result in an enhancement of these effects. However, with respect to smoking abstinence, comparable results were only found in groups receiving specific training in self-efficacy. It was suggested that the variability of findings in this study as well as those in the literature subsequent and relating to Foxx and Brown's (1979) procedure might be accounted for using Bandura's (1977) self-efficacy concept.     

Physiological and psychological effects of acute intentional hyperventilation

Research is reviewed which suggests that hyperventilation syndrome is an underdiagnosed disorder for the presentation of many patients experiencing apparent anxiety states. In a test of this hypothesis, 21 normal individuals (9 female) underwent a 2 min period of intentional hyperventilation following a 10 min baseline phase. Hyperventilation was accompanied by increased subjective anxiety and tachycardia, and indications of peripheral vasoconstriction. Following hyperventilation, Ss experienced increased levels of state anxiety and perceived autonomic arousal, as indexed by self-report instruments. These results support the hypothesis that undiagnosed hyperventilatory phenomena may be etiologically implicated in states of pathologic anxiety.