Effect of concurrent visual feedback on acquisition of a weightlifting skill

Practice in front of a mirror is a common procedure for activities such as dance, gymnastics, and other sports. The purpose of this study was to examine the effect that performing with concurrent visual feedback from a mirror had on the acquisition of the power clean movement. 18 college-age males who had no prior experience with the power clean movement served as subjects who were assigned to one of two groups. One group had use of a mirror during the practice trials and the other practiced without the mirror. All subjects viewed an instructional videotape and had practice trials. All subjects were evaluated for proper technique on a pretest, a posttest without the mirror, and a posttest with the mirror. Analysis showed a significant difference between pre- and posttest performances for both groups and a significant difference between groups on the posttest performances with the mirror. Evidently the videotaped instruction was sufficient to allow both groups to improve in performance of the power clean. Differences in posttest performances with the mirror reflected the type of feedback (with or without the mirror) available during training.     

Further explorations in empowerment theory: An empirical analysis of psychological empowerment

Developed empowerment theory and replicated previous research on citizen participation and perceived control. Few investigators have designed studies that specifically test empowerment theory. This research further extends a theoretical model of psychological empowerment that includes intrapersonal, interactional, and behavioral components, by studying a large randomly selected urban and suburban community sample and examining race differences. Results suggest that one underlying dimension that combines different measures of perceived control may be interpreted as the intrapersonal component of psychological empowerment, because it distinguishes groups defined by their level of participation in community organizations and activities (behavioral component). The association found between the intrapersonal and behavioral components is consistent with empowerment theory. Interaction effects between race groups and participation suggest that participation may be more strongly associated with the intrapersonal component of psychological empowerment for African Americans than for white individuals. Implications for empowerment theory and intervention design are discussed. The authors express appreciation to Steven Rosenstone who was the Principal Investigator for the Detroit Area Study from which the data for our study is based. We also thank Deborah A. Salem and the anonymous reviewers for their thoughtful comments on earlier drafts of this paper.     

Primacy of dimensions in vibrotactile perception: An evaluation of early holistic models

Early holistic models of perception presume that stimuli composed of interacting dimensions can be experienced initially as undifferentiated. This view, formalized through recourse to a Euclidean geometry of perceptual space, predicts that the orientation of axes used to create stimulus sets is unimportant to performance in speeded classification. We tested this idea by using the interacting vibrotactile dimensions of pitch and loudness. Despite perceivers’ relatively poor experience with these dimensions, we showed that the orientation corresponding to pitch and loudness was unique in vibrotactile perceptual space; subjects classified stimuli more efficiently at this orientation than at other orientations. Certain holistic models also claim that when stimulus differences are small, perceivers can recognize change without distinguishing the kind of change. We tested this idea by using a signal detection analysis of unspeededsame—different decisions. We found that subjects’ ability to notice the kind of change equaled their ability to notice the change alone. In view of these results, which indicate that pitch and loudness are primary in vibrotactile perception, we detail a new conception of dimensional interaction.     

Negative afterimages and the McCollough effect

Four experiments were conducted to test earlier claims about the relationship between the negative afterimage and the McCollough effect. The first claim (Hansel & Mahmud, 1978) is that long-lasting afterimages occur when induced by the same alternating-stimulus procedure as that used to induce the McCollough effect. The second claim (Murch & Hirsch, 1972) is that afterimages can themselves induce McCollough effects if they are induced and paired sequentially with grating patterns. In testing these claims, a reliable computer-controlled color-cancellation technique developed earlier was used to measure the apparent color of both afterimages and McCollough effects objectively. No support was found for the first claim following alternative presentation of two homogeneously colored regions for total periods of 5 min (Experiment 1) and 20 min (Experiment 2). The second claim was fully supported: After an induction period of 7.3 min, a McCollough effect occurred for a red-vertical pairing but not for a green-horizontal pairing (Experiment 3); but after an induction period of 20 min, McCollough effects occurred strongly for both pairings (Experiment 4). The theoretical implications of these outcomes are considered in the context of recent theories of color and pattern processing in the visual system.