Attention to Color: An Analysis of Selection, Controlled Search, and Motor Activation, Using Event‐Related Potentials

Abstract

In this study the organization of information processing in a selective search task was examined by analyzing event-related potentials. This task consisted of searching for target letters in a relevant (attended) color. The ERPs revealed two different effects of attention: an early occipital negativity (+/- 150 ms) reflecting feature-specific attention, and a later, central N2b component (+/- 240 ms) reflecting covert orienting of attention. A later, prolonged negativity (search-related negativity) (+/- 300 ms), maximal at Cz, was related to controlled search to letters in the attended color. Detection of relevant targets resulted in a parietal P3b component. Depending on stimulus presentation conditions an earlier response to both attended and unattended targets was found: an N2 component (+/- 250 ms). In these same conditions, C'3-C'4 asymmetries (Corrected Motor Asymmetries--CMA) suggested motor activation at +/- 300 ms, in the same time range as search-related negativity. It was argued that N2 and CMA suggest the existence of a preattentive target detection system, operating in parallel with a slower serial attentive system, as reflected by N2b and search negativity.

Attention to Features Precedes Attention to Locations in Visual Search: Evidence from Electromagnetic Brain Responses in Humans

“…It is instructive to compare the present results with previously reported feature-selective modulations of the ERP response in the N1 time range and beyond (Harter and Previc, 1978;Harter and Guido, 1980;Hillyard and Münte, 1984;Wijers et al, 1989;Anllo-Vento and Hillyard, 1996;Heslenfeld et al, 1997). In most of these studies, all stimuli were presented at attended locations, making it impossible to determine the relationship between attention to spatial and nonspatial features.…”

Event-related potential correlates of transient attention shifts to color and location

“…On the basis of these results, Mangun & Hillyard (1990) have proposed that spatial attention may consist of 'sensory gating' processes that modulate sensory processing in afferent visual pathways. In contrast, attending to non-spatial attributes like color, orientation, contour, or spatial frequency results in an enhanced negativity elicited by attended stimuli that starts beyond 150 ms and may extend up to 300 ms post-stimulus (Harter & Previc, 1978;Harter & Guido, 1980;Harter, Aine & Schroeder, 1982;Previc & Harter, 1982;Aine & Harter, 1984;Wijers, Mulder, Okita, Mulder & Scheffers, 1989;Wijers, Lamain, Slopsema, Mulder & Mulder, 1989;Kenemans, Kok & Smulders, 1993). The fact that attending to various non-spatial attributes results in qualitatively similar ERP modulations is in line with the general assumption that different non-spatial stimulus features are processed within a common visual sub-system, the so-called 'ventral pathway' (Ungerleider & Mishkin, 1982).…”

Electrophysiological evidence for temporal overlap among contingent mental processes.

“…Although both psychophysiological and performance measures have provided evidence against fully discrete transmission under certain conditions (see reviews by Miller, 1988Miller, , 1991, these findings neither rule out asynchronous discrete coding models nor justify the generalization that transmission is never discrete for any pair of contingent stages for any possible task and stimulus combination. Indeed, convincing evidence for discrete transmission under certain circumstances has been obtained (e.g., Gottsdanker & Shragg, 1985;Miller, 1985;Sanders & Houtmans, 1985;Wijers, Mulder, Okita, Mulder, & Scheffers, 1989; see also reviews by Miller, 1988Miller, , 1991and van der Molen, Bashore, Halliday, & Callaway, 1991).…”