On the control of visual spatial attention: evidence from human electrophysiology

Abstract

We used electrophysiological methods to track the deployment of visual spatial attention while observers were engaged in concurrent central attentional processing, using a variant of the attentional blink paradigm. Two visual targets (T1, T2) were presented at a stimulus onset asynchrony of either 200 ms or 800 ms. T1 was a white digit among white letters presented on a dark background using rapid serial visual presentation at fixation. T2 was another digit that was presented to the left or right of fixation simultaneously with a distractor digit in the opposite visual field, each followed by a pattern mask. In each T2 display, one digit was red and one was green. Half of the subjects reported the red digit and ignored the green one, whereas the other half reported the green digit and ignored the red one. T1 and T2 were reported in one block of trials, and only T2 in another block (order counterbalanced across subjects). Accuracy of report of T2 was lower at short SOA than at long SOA when both T1 and T2 were reported, but was similar across SOA when only T2 was reported. The electrophysiological results focused on the N2pc component, which was used as an index of the locus of spatial attention. N2pc was reduced in amplitude when subjects reported T1, and particularly so at the short SOA. The results suggest that attention to T1 interfered with the deployment of visual spatial attention to T2.

Electrophysiological evidence of central interference in the control of visuospatial attention

“…The results of the present study extend and provide converging support for related findings using the attentional blink (AB) paradigm (Jolicoeur, Sessa, Dell'Acqua, & Robitaille, 2006a, 2006b). In the AB paradigm, accuracy of report for some aspect of a masked T 2 , such as target identity, suffers when T 2 is presented at a short SOA following a T 1 that must also be processed.…”

“…In the AB paradigm, accuracy of report for some aspect of a masked T 2 , such as target identity, suffers when T 2 is presented at a short SOA following a T 1 that must also be processed. Jolicoeur et al (2006aJolicoeur et al ( , 2006b used T 2 displays similar to the ones used in the present work following presentation of another visual stimulus (T 1 ) that did not require an immediate response. The N2pc was sharply attenuated by the AB.…”

The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation

“…These effects are supported by the experimentally observed suppression ('freezing') of the N2pc during the AB period [136,137]. During this period, amplification and ignition in the visual system involving LIP, FEF and the pulvinar are disabled.…”

Measurement of ERP latency differences: A comparison of single‐participant and jackknife‐based scoring methods

“…Others, who have used bilateral displays with only one distractor, have argued that the N2pc reflected target enhancement processes (e.g., Eimer, 1996). Nonetheless, even if there is still an ongoing debate on the specific processes that underlie the N2pc, it is widely accepted as a valid index of covert visual-spatial attention in light of several results reviewed by Woodman and Luck (2003), and it has been widely used in the study of visual-spatial attention (e.g., Brisson & Jolicoeur, 2007a, 2007b, 2007cDell'Acqua, Sessa, Jolicoeur, & Robitaille, 2006;Eimer & Mazza, 2005;Jolicoeur, Sessa, Dell'Acqua, & Robitaille, 2006a, 2006bWascher, 2005;Woodman & Luck 2003). The N2pc differs from N1 and P3 because it is measured from a difference wave, which tends to increase variability.…”