Kinematic Displays of Volleyball Players' Bearing Weight of Run-Jump-Block: Visual Perception and Judgment

Abstract

The present study examined whether observers were able to determine the weight that a volleyball player bearing while he doing run-jump-block in kinematic displays. Two male volleyball players served as actors (height and weight: 178cm, 75kg, and 176cm, 73kg, respectively.). They performed the run-jump-block and were filmed by a camera (digital camera, Sony). Bright patches were attached to their main joints of the right and left sides, and weights were attached to their waist. The weights were 0%, 7%, 14% and 21% of the actors' body weight. The film showed the kinematic display of the main joints. Fifty-eight undergraduates served as observers and they were required to observe the film, judge the weights that the player bearing, and fill out the Information Sources Questionnaire. First of all, simple t test showed that the accuracy of judgment of the weights was different from 25%, the probability. This indicated that the observers were able to discriminate the four different weights. Secondly, one-way repeated measures ANOVA showed a significant Weight effect, and post hoc analysis revealed that the accuracy of judgment in the 21%-weight condition was higher than the other 3 conditions, and the accuracy of judgment in the 0%-weight condition was higher than the 7%-weight and the 14%-weight conditions. Finally, jumping height, hang time, and speed were the main source of information for perceptual judgment. The present study supports that the kinematic display contains sufficient information (Runeson & Frykholm, 1981) which affords accurate perceptual judgment of four different weights. Perceptual judgments of the heaviest and the lightest weights are in the highest accuracy. Individuals are able to perceive the kinetics changes from kinematic displays.