Rapid eye and hand responses in an interception task are differentially modulated by context-dependent predictability

Abstract

Humans can quickly generate eye and hand responses to unpredictable changes in the environment. Here, we investigated eye-hand coordination in a rapid interception task where human participants used a virtual paddle to intercept a moving target. The target moved vertically down a computer screen and could suddenly ‘jump’ to the left or right. In high-certainty blocks, the target always jumped, and in low-certainty blocks, the target only jumped in a portion of trials. Further, we manipulated response urgency by varying the time of target jumps, with early jumps requiring less urgent and late jumps requiring more urgent responses. Our results highlighted differential effects of certainty and urgency on eye-hand coordination. Participants initiated both eye and hand responses earlier for high-certainty compared to low-certainty blocks. Hand reaction times decreased and response vigor increased with increasing urgency levels. However, eye reaction times were lowest for medium-urgency levels and eye vigor was unaffected by urgency. Across all trials, we found a weak positive correlation between eye and hand responses. Taken together, these results suggest that the limb and oculomotor systems use similar early sensorimotor processing; however, rapid responses are modulated differentially to attain system-specific sensorimotor goals.