The role of kinematic information in movement prediction and deception

Abstract

INTRODUCTION: Sensitivity to information contained within movement patterns is fundamental to successful anticipation and deception avoidance in many sports. The purpose of this study was to ascertain if expert perception of deceptive intent is dependent upon the pick-up of information of a kinematic or non-kinematic origin. METHODOLOGY: 13 expert (Olympic level), 18 intermediate and 15 novice badminton players viewed video clips of opposing players hitting strokes, either with or without deceptive intent, to either the front or back half of the court. The display, which simulated that normally available on-court, was occluded at one of four different times relative to the point of racquet-shuttle contact (viz., 160 ms before, 80 ms before, at, or 80 ms after contact). Half of the trials showed the display in normal format and half in a point-light format (white dots for joint centres against a black background). The latter condition provided only kinematic sources of information while the former also made non-kinematic cues such as colour, contour, texture and facial expressions available. Participant error in predicting stroke depth was examined as a function of skill level, deceptive intent, display mode and time of occlusion. RESULTS: For the video display mode a significant main effect was found for deceptive intent with greater prediction error invoked for all participants for the deceptive strokes. A significant group×occlusion interaction was also observed due to the earlier pick-up of information (in the period from 160 to 80 ms prior to contact) by the expert players for both deceptive and non-deceptive strokes. For the point-light display mode prediction accuracy was comparable for both the deceptive and non-deceptive strokes. An expert advantage remained on the point-light displays but the time of initial pick-up of useful information was delayed (to the period from −80 ms until contact). CONCLUSION: Non-kinematic sources of information appear to be most critical for the effective use of movement pattern deception. Removing non-kinematic information through point-light displays eliminates prediction accuracy differences between deceptive and non-deceptive strokes and also delays the time at which expert players first pick-up useful information. Both the very early pick-up of advance information by experts and the effectiveness of deception therefore appear to be dependent upon the presence of information additional to the immutable kinematic signature of the movement.