Impulse characteristics in rapid movement: implications for impulse-variability models

Three untested assumptions of the impulse-variability model were examined in two experiments utilizing rapid, uni-planar limb movements. Experiment 1 varied movement distance (A) and movement time (MT) in a rapid-timing paradigm where the subject moved a lever through a certain distance in a certain time. Experiment 2 varied A in a reversal response where the S made a rapid elbow flexion and extension in a given MT. Displacement recordings were made on every trial. KR (knowledge of results) about MT was given after every trial. The results can be summarized as follows: (a) As predicted by the model, variations in impulse size and velocity were directly related to the impulses size; (b) There was no correlation between the accelerative and decelerative impulse durations recorded during the reversal response supporting the notion that the impulses might be independent; (c) Negative correlations (-.20 to -.50) were demonstrated between peak acceleration and impulse duration for both experiments, counter to the predictions of the model; and (d) Counter to the predictions of the model, timing error (VEt) increased as A decreased for rapid-timing responses. When the correlational results are taken into account, the model has the capacity to account for curvilinear relationships between relative timing error and movement speed. Overall, the results suggest that the impulse variability model requires some restructuring before it can be considered a viable model for the control of rapid limb movements.     

An examination of rapid positioning movements with spatiotemporal constraints

Unidirectional positioning movements with spatiotemporal constraints were examined as a test of impulse-timing theory (Schmidt, 1976; 1980; Wallace, 1981). Movements were examined at the kinematic, kinetic, and neuromuscular levels in three experiments. In the first experiment, displacement was held constant while five different movement times were examined. Both amplitudes and durations of the EMG and the kinetic variables were related to movement time. The results generally support the impulse-timing model. In the second experiment, movements were performed to a target at each of four distances in a constant movement time. EMG and force amplitudes and, unexpectedly, accelerative-force duration were modulated to achieve changes in displacement when movement time was constant. In the third experiment, movement time and displacement were simultaneously varied resulting in four conditions with equal average velocities. The results of this experiment were not as clear and exhibited individual differences. EMG duration did not always vary with changes in movement time. The results of all three experiments could not be adequately accounted for by the impulse-timing model.     

Latency and frequency reports to the Necker cube illusion: effects of hypnotic susceptibility and mental arithmetic

An experiment (N = 32) was conducted to assess latency of first apparent reversal (AR) and AR frequency while observing the Necker cube illusion. Subjects who were either high in hypnotic susceptibility (susceptibles) or low in hypnotic susceptibility (resistant subjects) observed the cube either while performing or not performing mental addition problems. Susceptibles reported perceiving the first AR more quickly and a greater frequency of ARs than did resistant subjects. Also, latency of the first AR was negatively correlated with AR frequency. These results were interpreted in terms of the ability of susceptibles to allocate concentrative or selective attention in a manner that was conducive to faster performance, when faced with competing tasks.     

Daily versus major life events as predictors of symptom frequency: a replication study

Predictions of physical symptomatology by daily life events and by major life events were compared, replicating and expanding work reported by DeLongis, Coyne, Dakof, Folkman, & Lazarus (1982). Analyses of daily, prospective data collected on 79 married men for 90 days demonstrated that daily, undesirable events were better predictors of symptom frequencies than either past, major life events or daily, desirable events. These results, similar to those found by DeLongis et al. (1982), were further explored by examining "healthy" subjects versus subjects with prior medical conditions. Undesirable daily events were a much stronger predictor of physical symptoms in the healthy group than in the prior medical conditions group.     

Type A behavior pattern and the judgment of control

We investigated the control judgments of Type A and B actors and observers after five tasks in which actual response-outcome contingency and success were varied systematically. Results indicated that, overall, actors provided higher control judgments than did observers, and both actual contingency and success influenced judged control. Type A and B actors did not differ in their self-perceptions of control but observers judged the Type A actors to have exerted more control than the Type B actors, primarily on positive contingency tasks. These findings suggest that Type As, because of their more active, dynamic style, may be credited by observers with more control or competence than is warranted. By contrast, the more relaxed style of the Type B may lead to lower than warranted evaluations of control or competence. Lastly, Type As were found to learn the contingencies better than Type Bs with important implications for the actual exercise of control.     

Adjustment to rape

This questionnaire study of rape victims' reactions, causal attributions for the rape, coping behaviors after the rape, and psychological adjustment to the rape were examined. As in previous research, high levels of behavioral and characterological self-blame for rape were found. Contrary to prior hypotheses, behavioral self-blame was not associated with good adjustment. Rather, both behavioral and characterological self-blame were associated with poor adjustment. Societal blame was the only causal attribution for rape that was unassociated with adjustment. Remaining at home and withdrawing from others were both associated with poor adjustment, and the use of stress reduction techniques was associated with good adjustment. The implications of the results for theories of victimization and for clinical interventions with rape victims are discussed.     

Peers' granting of control to women with different sex role identities: implications for depression

This investigation is one of a series of studies seeking to determine the degree of control given to women with different sex role identities. This study focused on the extent to which peers were willing to grant control to women with different sex role identities if working individually with each woman on various two-person tasks. The results indicated that women with different sex role identities were granted different amounts of control by their peers as a function of the type of two-person task under consideration. Women rated high on masculinity were granted greater control on enjoyable and creative tasks, whereas women rated low in masculinity were given more control on methodical and less enjoyable tasks. Women judged high in femininity were given control on tasks requiring interpersonal skills. These findings were discussed within the context of learned helplessness theory as a possible aid in understanding why more women than men become depressed.     

Drug-behavior interaction history: modification of the effects of morphine on punished behavior.

Squirrel monkeys were trained to respond under a multiple fixed-interval, fixed-interval schedule in which the first response after 5 min terminated a visual stimulus in the presence of which electric shocks could occur. During one component of the schedule, correlated with one color of stimulus lights, every 30th response also produced electric shock; responding was suppressed during this component to approximately 10 to 12% of that occurring in the alternate component in which responding was not punished. In contrast to previous research, morphine (0.03 to 1.0 mg/kg) increased punished responding. Unpunished responding, however, was either not affected or decreased at doses of morphine that increased punished responding. Increases in rate of punished responding also occurred when the single-schedule punishment condition was studied alone in these animals. Subsequent experimentation, which systematically analyzed the development of the rate-enhancing effects of morphine on punished responding, involved the study of drug effects in additional monkeys trained initially under a single-schedule punishment condition. The effects of morphine on punished responding were studied before, after, and then during exposure to the multiple schedule that included a component in which responding was not punished. Increases in response rate with morphine did not occur until it was administered during exposure to the multiple schedule that included a component in which responding was not punished. As with the other monkeys, once the rate increases in punished responding occurred under the multiple schedule, these effects of morphine persisted, even when the multiple schedule was removed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Syntactic decoding times of learning disabled children

Syntactic decoding reaction times of 20 learning disabled children comprising two groups of subjects (mean age of 8 and 13 yr., respectively) were compared to the responses of normal controls matched for age and sex. An analysis of variance procedure showed that the learning disabled children and their normal peers did not differ significantly in responses to the experimental stimuli. This held true regardless of linguistic complexity, suggesting that delays in processing elementary syntactic constructions are not a concomitant of learning disabilities.