Global effect of a nearby distractor on targeting eye and hand movements.

Eye-hand coordination was investigated with the global effect paradigm. In this paradigm, saccades typically land in between the target and a nearby presented distractor, the configuration's center of gravity. This so-called global effect, or spatial averaging, is attributed to incomplete target selection. Four experiments demonstrated a similar effect for hand movements; thus, eye and hand are coupled during target selection. However, under some conditions the global effect was different for eye and hand, suggesting that their coupling is not achieved through a shared target representation. Instead, eye and hand seem to use 2 separate target representations that exchange information. The convergent amplitudes of eye and hand with simultaneous execution support this interpretation. Latencies showed a similar converging pattern.