Interceptive action involving coordination of a target with preceding motion of the head

Abstract

　Various studies have investigated the act of spatiotemporally matching one’s motion with that of a moving object: a process known as “interceptive action”. The angle between a target and the action performer is referred to as the Bearing Angle (BA). Accurate interceptive actions can be implemented by maintaining the BA (Constant Bearing Angle Strategy: CBA strategy). However, factors affecting the completion of interceptive actions based on the CBA strategy have not been investigated to date. The purpose of this study was to examine how prediction of changes in target velocity can affect the strategy of interceptive action. We also examined the characteristics of head rotation during interceptive action. Participants (N=15) were required to watch a target, move from the starting point to the interception point as linearly as possible, match the time of target arrival, and complete their movement as close to the target as possible. Two conditions were presented randomly: a control condition under which the target moved at a constant velocity (NC condition) and a random condition under which the target moved at an irregular velocity (I+NC condition). The two conditions were compared using δCBA_H and %HDA. δCBA_H is defined as a measure of coordination between a target and a participant during an interceptive action, whereas %HDA is defined as a measure indicating where the head orientation of the participant is located between the target and the arrival point. These measures were analyzed from the perspective of velocity and angle, target presenting conditions, and movement intervals. The main results indicated that the δCBA_H error increased under I+NC relative to the NC condition for low-velocity tasks with a BA of 45 degrees. Furthermore, %HDA showed that the I+NC condition directed the arrival point to a greater degree than the NC condition. These findings suggest that it is difficult to maintain the CBA strategy under conditions where prediction is made when the distance to the target is shorter and the velocity lower. Therefore, it is suggested that the task may be conducted by preceding the direction of the head arrival point using peripheral vision.