The synchronization of human arm movements to external events

Previous research revealed the existence of coupling mechanisms (e.g. iso-d irectionality) at the level of perception and action. The present experimen t investigated how the strength of the perception-action coupling affected synchronization performance. Arm movements were to be synchronized with a m oving light that traveled back and forth from the left to the right side of a runway. Four experimental conditions were administered representing the orthogonal combination of two viewing conditions (intermittent vs. continuo us) and two synchronization modes (in-phase, i.e. arm moving in the same di rection as the light vs, anti-phase, i.e. arm moving in the opposite direct ion). Performance outcome measures, movement kinematics, and relative phase were used to examine the data. The results revealed a better synchronizati on performance when the arm and light traveled in the same direction (iso-d irectionality) during the continuous viewing condition. Apparently, the str ength of the perception-action coupling has a severe impact on the quality of the synchronization of an arm movement to an external event. (C) 2000 Pu blished by Elsevier Science Ireland Ltd.