Academic journal article Attention, Perception and Psychophysics

Attentional Dynamics Mediated by Subcortical Mechanisms

Academic journal article Attention, Perception and Psychophysics

Attentional Dynamics Mediated by Subcortical Mechanisms

Article excerpt

Published online: 1 My 2014

(Q> The Psychonomic Society, Inc. 2014

Abstract Following a salient cue that attracts attention to a specific spatial location, perceptual processing of information at that location is facilitated if the interval between the cue and target is brief, or, is inhibited if the interval between the cue and target is long. The mechanisms mediating these attentional dynamics continue to be the subject on ongoing debate. On one classic account, facilitation and inhibition of return (IOR) are two ends of a continuum, generated by the same underlying mechanism. Other accounts have postulated that these two attentional processes emerge from independent systems. To address these alternatives, we report data from three experiments in which a cue and its ensuing target are presented to the same or different eyes at varying cue-target intervals. Whereas the onset of facilitation was apparent earlier when the cue and target shared the eye-of-origin, the onset of IOR was not affected by the eye to which the cue and target were presented. This finding implicates at least some, if not full, independence in the system(s) that give rise to attentional facilitation and IOR, and, moreover, suggests that facilitation may be more reliant on subcortical levels of the visual pathways than IOR.

Keywords Spatial attention * Exogenous orienting * Inhibition ofretum * Subcortical mechanisms * Monocular presentation

Introduction

Following a salient, exogenous cue that attracts attention to a specific location in the environment, perceptual processing of information appearing at that location is facilitated if the interval between the cue and target is brief, or, is inhibited if the interval between the cue and target is long. For example, under conditions of exogenous spatial cueing (Posner & Cohen, 1984), at short stimulus onset asynchronies (SOAs), reaction time (RT) for valid trials (i.e., target and cue presented at same spatial location) is faster than for invalid trials (i.e., target and cue presented at differing spatial locations)-an effect generally referred to as attentional facilitation. At longer SO As, the converse is true: RT is slower for valid than for invalid trials. This latter effect, termed inhibition of return (IOR), has generated keen interest and considerable discus- sion about its underpinnings and its relationship to attentional facilitation. Furthermore, in addition to being a perceptual phenomenon, IOR also manifests as a 'motor' phenomenon (Taylor & Klein, 1998). For example, Sumner, Nachev, Vora, Husain and Kennard (2004) demonstrated a dissociation be- tween perceptual and motor IOR in the eye-movement sys- tem, in that perceptual IOR but not motor IOR is observed in response to S-cone stimuli that are presumably not processed by the SC (but see Hall & Colby, 2014). Also, IOR has also been demonstrated in space-based (Sapir, Hayes, Henik, Danziger, & Rafal, 2004; van Koningsbruggen, Gabay, Sapir, Henik, & Rafal, 2010) and in object-based coordinates (Becker & Egeth, 2000; Tipper, Jordan, & Weaver, 1999) and not only in retinotopic coordinates, suggesting potentially that more complex computations might be involved. There is still ongoing debate regarding the psychological and neural mech- anisms underlying these facilitatory and inhibitory attentional effects, and several contrasting proposals have been offered to explain the mechanism/s underlying the reflexive attentional dynamics. The present study focuses on the attentional dy- namics that are engaged when participants perform a visual detection task, and thus the focus is on the more perceptual aspects of enhancement and inhibitory mechanisms.

Attentional dynamics: unitary mechanism

The well-accepted reorienting theory offers an explanation in which both of these attentional dynamics, facilitation and IOR, emerge from a single underlying process (Klein, 2000). The theory is framed in terms of attention operating as a spotlight and postulates that the presence of the spotlight at a particular location facilitates foraging and other search behav- iors. …

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