Abstract
Attentional capture is known to be modulated by the hemifield of stimulus presentation. Previous research has demonstrated stronger capture by stimuli in the temporal as compared to the nasal visual hemifield (Rafal, Henik, & Smith, 1991). We measured N2pc components as an index of attentional object selection in response to bilateral displays. Participants' task was to identify the digit in a pre-specified target color and to ignore the other nontarget-color digit. In different blocks, the right eye or the left eye was patched, so that the digit in the temporal visual hemifield was projected onto the nasal hemiretina and the nasal digit to the temporal hemiretina. As expected, N2pc components were elicited contralateral to the visual field where a target was presented. Critically, this component was attenuated and delayed for targets on the nasal hemiretina relative to targets that stimulated the temporal hemiretina. This result appears opposite to what would be expected if targets in the temporal visual field attract attention more efficiently, and suggests that the N2pc reflects the combined effects of attentional target selection and distractor suppression (Hickey, Di Lollo, & McDonald, 2009). Distractor suppression triggers a Pd component that is opposite in polarity to the target N2pc, and emerges during the same time interval. Distractor objects in the temporal visual field require stronger attentional suppression than nasal distractors, and therefore elicit larger Pd components, resulting in larger net N2pc components on trials where temporal distractors stimulated the nasal hemiretina and nasal targets were simultaneously projected onto the temporal hemiretina.
Meeting abstract presented at VSS 2014