Distractor interference in selective reaching: effects of hemispace, movement direction, and type of movement

In this study we investigated the influence of hemispace, movement direction, and type of movement on distractor interference in selective reaching. Participants reached for a green target while ignoring a simultaneously presented red distractor. In Experiment 1 participants performed rightward or leftward movements within the right or the left hemispace using their dominant (i.e., right) hand. Reaction times, movement times, and percentage errors were recorded. Results showed significant interference effects in movement time, not in reaction time. Importantly, movement time interference was found to be smaller for leftward than for rightward movements. However, in Experiment 1, movement direction was confounded with type of movement (i.e., abduction vs. adduction). In Experiment 2 we disentangled these two factors by having participants perform rightward and leftward movements with right and left hands. Results indicated again that leftward movements were less prone to distractor interference than rightward movements, regardless of the responding hand. This phenomenon is interpreted in terms of a left hemisphere superiority in online feedback-processing during goal-directed movements in right-handers.