Academic journal article Attention, Perception and Psychophysics

The Effects of Saccade-Contingent Changes on Oculomotor Capture: Salience Is Important Even beyond the First Oculomotor Response

Academic journal article Attention, Perception and Psychophysics

The Effects of Saccade-Contingent Changes on Oculomotor Capture: Salience Is Important Even beyond the First Oculomotor Response

Article excerpt

Published online: 31 May 2014

# The Psychonomic Society, Inc. 2014

Abstract Whenever a novel scene is presented, visual salience merely plays a transient role in oculomotor selection. Unique stimulus properties, such as a distinct and, thereby, salient color, affect the oculomotor response only when observers react relatively quickly. For slower responses, or for consecutive ones, salience-driven effects appear completely absent. To date, however, the circumstances that may reinstate the effects of salience over multiple eye movements are still unclear. Recent research shows that changes to a scene can attract gaze, even when these changes occur without a transient signal (i.e., during an eye movement). The aim of the present study was to investigate whether this capture is mediated through salience-driven or memory-guided processes. In three experiments, we examined how the nature of a change in salience that occurred during an eye movement affected consecutive saccades. The results demonstrate that the oculomotor system is exclusively susceptible to increases in salience from one fixation to the next, but only when these increases result in a uniquely high salience level. This suggests that even in the case of a saccade-contingent change, oculomotor selection behavior can be affected by salience-driven mechanisms, possibly to allow the automatic detection of uniquely distinct objects at any moment. The results and implications will be discussed in relation to current views on visual selection.

Keywords Oculomotor capture . Attentional capture . Selective attention . Visual attention . Visual salience

Introduction

In the literature on attention and oculomotor behavior, it is a common view that goal-driven and stimulus-driven signals both influence target selection. Not only do the goals of an observer determine where attention will be allocated, but also the properties of stimuli themselves affect selection (e.g., Corbetta & Shulman, 2002;Theeuwes,1994). However, a number of relatively recent studies suggest that the stimulus- driven effects on oculomotor behavior are remarkably tran- sient (Donk & van Zoest, 2008; Henderson, Weeks, & Hollingworth, 1999; Siebold, van Zoest, & Donk, 2011;van Zoest & Donk, 2005, 2006; van Zoest, Donk, & Theeuwes, 2004; van Zoest, Donk, & Van der Stigchel, 2012). Does that imply that visual salience is merely of minor relevance in the control of our everyday eye movements? In a series of exper- iments, we investigated how salience changes implemented during an eye movement affect subsequent oculomotor selec- tion behavior. What are the circumstances under which stimulus-driven signals can be given a significant role to play beyond a first eye movement in a visual scene?

In simple search tasks, merely those saccades that are initiated rapidly after the presentation of a search display appear to be stimulus driven, since only then does perfor- mance vary as a function of target and distractor salience (Siebold et al., 2011; van Zoest & Donk, 2005, 2006;van Zoest et al., 2004). In fact, an approximate 250 ms after search display onset, participants often fail to move their eyes toward the most salient singleton in a display (Donk & van Zoest, 2008). Furthermore, the influence of salience is not reinstated for a second oculomotor response (Siebold et al., 2011)and so, presumably, neither for the eye movements beyond that. For instance, in Experiment 2 of Siebold et al., participants were asked to make a speeded saccade toward the only right- tilted singleton in a search display consisting of a grid of vertical line segments and two left-tilted singletons. Relative to the orientation of the background and distractor lines, the target could be most, medium, or least salient. The results indicated that, whereas target salience influenced the initial saccade, second saccades were completely unaffected. These results imply that even though the retinal input alters dramatically from one fixation to another, the effects of salience do not reappear. …

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