Information feedback and the learning multiple-degree-of-freedom activities

The influence of information feedback on the learning of a multiple-degree-of-freedom activity, the overhand throw, was investigated. During learning, feedback was presented in the form of knowledge of results, knowledge of performance, knowledge of performance with attention-focusing cues, or knowledge of performance with error-correcting transitional information. Across 12 practice sessions, performance was assessed with respect to both throwing distance and throwing form. Subjects provided with knowledge of performance along with transitional information demonstrated significant gains in throwing distance, compared with subjects receiving knowledge of performance or knowledge of results alone. Movement form ratings followed the same trend. Providing learners with cues to focus their attention on the relevant aspects of knowledge of performance or directly providing transitional information was a better aid to the acquisition of throwing form than providing knowledge of results or knowledge of performance alone. These results support the hypothesis that knowledge of results may not be the most potent form of feedback in multiple-degree-of-freedom activities and that knowledge of performance, when combined with additional information, can lead to significant gains in skill acquisition.     

The effects of objectives and constraints on motor control strategy in reciprocal aiming movements

The goal of this study was to examine how the kinematics of reciprocal aiming movements were affected by both the objective of the movement and the constraints operating on that movement. In Experiment 1, the objective of the movement was indirectly manipulated by capitalizing on the fact that subjects determine their own accuracy and speed limits, despite uniform task instructions to move as quickly and accurately as possible. A Fitts' type reciprocal aiming paradigm was employed, in which 69 subjects were asked to move a stylus repetitively between two spatially separated targets. Four target widths were orthogonally combined with four movement amplitudes, resulting in 16 conditions. Movements were made on an X-Y digitizing tablet. Based on the mean variable error produced on both targets, subjects were differentiated post hoc into three movement objective groups: speed, accuracy, and speed-plus-accuracy. Kinematic analyses revealed that the programming and execution of movements were systematically influenced by both the movement objective and the movement constraints. That is, movement time, peak velocity, dwell time, acceleration and deceleration time, normalized acceleration and normalized deceleration varied systematically as a function of both the speed-accuracy movement objective and the movement constraints of target size and movement distance. Moreover, the consequences of changing the constraints of the movement were affected by an interaction with the objective of the movement. In Experiment 2, the objective of the movement was directly manipulated by varying speed and/or accuracy instructions to subjects. The basic results of Experiment 1 were substantiated. Overall, the results were consistent with the view that motor control is dependent upon sensory consequences.     

Evidence for an error deadzone in compensatory tracking

Humans and monkeys show intermittent arm movements while tracking moving targets. This intermittency has been explained by postulating either a psychological refractory period after each movement and/or an error deadzone, an area surrounding the target within which movements are not initiated. We present a technique to detect and quantify the size of this deadzone, using a compensatory tracking paradigm that distinguishes it from a psychological refractory period. An artificial deadzone of variable size was added around a visual target displayed on a computer screen. While the subject was within this area, he received visual feedback that showed him to be directly on target. The presence of this artificial deadzone could affect tracking performance only if it exceeded the size of his intrinsic deadzone. Therefore, the size of artificial deadzone at which performance began to be affected revealed the size of the intrinsic deadzone. Measured at the subjects' eye, the deadzone was found to vary between 0.06 and 0.38 degrees, depending on the tracking task and viewing conditions; on the screen, this range was 1.3 mm to 3.3 mm. It increased with increasing speed of the target, with increasing viewing distance, and when the amplitude of the movement required was reduced. However, the deadzone size was not significantly correlated with the subjects' level of performance. We conclude that an intrinsic deadzone exists during compensatory tracking, and we suggest that its size is set by a cognitive process not simply related to the difficulty of the tracking task.     

Recovery of Locomotion in Monkeys With Spinal Cord Lesions

This study reanalyzes kinematically (via film) the pre- and postoperative locomotor behavior of 4 of the 10 monkeys with partial spinal cord lesions (T8) briefly described by Eidelberg, Walden, and Nguyen (1981). The behavior of the remaining 6 monkeys is qualitatively described. The analysis reveals that 5 of the animals initially exhibited unilateral hind limb stepping. Hind and forelimb cycle durations often differed postoperatively; the hind limbs commonly showed increased values, whereas forelimb cycle durations were reduced: ipsilateral interlimb phase values were usually inconsistent. A review of prior studies of primate spinal cord lesions indicates that sparing of the ventrolateral quadrant may not be essential for locomotor recovery (cf. Eidelberg, Walden, & Nguyen, 1981). Furthermore, this review as well as the kinematic analysis indicates that primates with very significant spinal lesions can stilI exhibit locomotor movements. Thus, although the primate's spinal cord seems less able than other mammals' to readily organize locomotor movements (Eidelberg, Walden, & Nguyen, 1981), the total absence of stepping in primates with completely transected cords is unexpected and warrants further research.     

Affect, personality, and social activity.

These studies examined relations between social activity and state and trait measures of Positive and Negative Affect. In Study 1 Ss completed scales relevant to 3-factor models of personality and a weekly mood and social activity questionnaire for 13 weeks. In Study 2 Ss completed measures of the 5-factor model of personality and a daily mood and social activity survey for 6-7 weeks. In within- and between-Ss analyses, socializing correlated significantly with state measures of Positive Affect and with trait measures of Extraversion/Positive Emotionality. These relations were relatively general across various types of positive affect and social events; however, specific types of social events also were differentially related to affect. In contrast, social activity had no consistent association with measures of Negative Affect or the other personality dimensions. The results support a temperamental view of Extraversion.     

Future-event schemas and certainty about the future: automaticity in depressives' future-event predictions.

The proposition was tested that depressives make predictions about the future based on a pessimistic future-event schema. Participants varying in depression predicted whether positive and negative events would happen to them (or to an average person) in the future by pressing yes or no at a computer terminal as quickly as possible, either under a concurrent attentional load or under no such load. As hypothesized, depressives predicted more negative events and fewer positive events than did mild depressives or nondepressives and showed greater automaticity in their predictions. That is, the attentional load did not increase depressives' response latencies for either negative or positive events, even though it did so reliably for both mildly depressed and nondepressed individuals. Depressives may thus possess a highly developed future-event schema that operates efficiently in enabling future-event predictions.     

Why do people need self-esteem? Converging evidence that self-esteem serves an anxiety-buffering function.

Three studies were conducted to assess the proposition that self-esteem serves an anxiety-buffering function. In Study 1, it was hypothesized that raising self-esteem would reduce anxiety in response to vivid images of death. In support of this hypothesis, Ss who received positive personality feedback reported less anxiety in response to a video about death than did neutral feedback Ss. In Studies 2 and 3, it was hypothesized that increasing self-esteem would reduce anxiety among individuals anticipating painful shock. Consistent with this hypothesis, both success and positive personality feedback reduced Ss' physiological arousal in response to subsequent threat of shock. Thus, converging evidence of an anxiety-buffering function of self-esteem was obtained.     

Mothers with hostile, Type A predisposing child-rearing practices.

The authors examined characteristics of Finnish mothers (N = 924) who use hostile child-rearing practices (i.e., they ignore the child, are punitive and irritable, and perceive the child as a burden), practices that have been shown (R?ikk?nen & Keltikangas-J?rvinen, 1992) to predispose children to Type A behavior. The results of this study indicate that two factors--Type A behavior in the mothers and the mothers' sociodemographic background (low occupational status, low educational level and young age)--increase the probability of the mothers' treating their children in a hostile manner. Also, the mothers of boys in this study reported more hostile child-rearing practices than the mothers of girls did.     

Parental values, reinforcement, and young children's prosocial behavior: a longitudinal study.

In this study, the authors assessed the relation of parental reinforcement and parental values to young children's prosocial behaviors. Parents' dyadic interactions with their 1- to 2-year-old children were videotaped in the home on two occasions approximately 6 months apart. The children also were videotaped playing with a peer at 3 1/2 to 4 1/2 years of age. Parental reinforcement of the children's prosocial behaviors was coded, as were the children's prosocial behaviors with the peer. The frequency of girls' spontaneous prosocial behaviors decreased in the early years; modest consistency was observed for boys (but not girls) across the two parental sessions. No relation existed between the frequency of children's prosocial behaviors with their parents and their behaviors with peers. Both maternal and paternal valuing of compliance were negatively related to the mothers' use of reinforcement for children's spontaneous prosocial behaviors. Parental reinforcement of compliant prosocial behaviors was negatively related to children's compliance with a peer's request for prosocial behavior and positively related to defensive behavior with the peer. Fathers' valuing of prosocial behavior was associated with children's compliance with the peer's requests for prosocial action. Parents who valued compliance had children who exhibited low levels of compliant prosocial behaviors with the peer, possibly because of the depressed level of peer interaction.