Electrophysiological indices of visual spatial attention and visual short-term memory

Pierre Jolicoeur

Visual event-related potentials (ERPs) provide powerful tools to study the mechanisms mediating the deployment of visual spatial attention, visual short-term memory, and interactions between spatial attention and central attention. In this talk I will summarize several sets of experiments focusing on the N2pc ERP component as a moment-to-moment index of the deployment of visual spatial attention. These studies explore how central attentional loads created in the context of paradigms used to study the attentional blink (AB) and the psychological refractory period (PRP) systematically modulate the N2pc, and presumably the ability to control visual spatial attention. Spatial attention is important for the selection of visual stimuli that are to be processed by later capacity-limited mechanisms. Visual short-term memory provides a temporary store for objects selected for further processing that has very limited storage capacity (about 3 or 4 objects). I will also discuss recent work involving a later component, which we call the SPCN (sustained posterior contralateral negativity), that appears to be a specific index of neural activity mediating the maintaince of information in visual short-term memory, and describe serveral experiments in which this activity is sharply affected by concurrent central processing demands.