Attention Amplifies Response Priming

We studied the influence of spatial visual attention on the time-course of primed pointing movements. We measured pointing responses to color targets preceded by color stimuli priming either the same or opposite response as the targets. Effects of visual attention at the prime/target locations were studied by giving endogenous attentional cues whose processing was a precondition for performing the task, or exogenous cues, varying both the cue-prime and the prime-target interval. Pointing trajectories revealed large priming effects such that pointing responses were first controlled by prime signals and then captured in mid-flight by target signals. Priming effects were strongly amplified when the relevant prime locations were visually attended at optimal cue-prime SOAs, with attention modulating the entire time-course of primed pointing movements. We propose that visual attention amplifies the earliest waves of visuomotor feedforward information elicited in turn by primes and targets.