Bilateral attentional advantage on elementary visual tasks.

We examined interactions between and within the left and right visual hemifields using elementary visual tasks. Each trial required identifying a letter at fixation and then either discriminating the orientation of (experiment 1) or detecting (experiment 2) peripheral Gabor targets. On half the trials Gabor distracters were presented between the Gabor targets, and were either restricted to one lateral hemifield (unilateral condition) or presented across the left and right hemifields (bilateral condition). Orientation discrimination and detection each exhibited bilateral superiority only when distracters were present. The results confirm bilateral superiority in attentional selection, even on these most elementary visual tasks.