Academic journal article Attention, Perception and Psychophysics

Spatial Attention and Reaction Times during Smooth Pursuit Eye Movement

Academic journal article Attention, Perception and Psychophysics

Spatial Attention and Reaction Times during Smooth Pursuit Eye Movement

Article excerpt

Published online: 16 December 2011

© Psychonomic Society, Inc. 2011

Abstract To examine the spatial shift of attention during smooth pursuit, we measured reaction times (RTs) to a visual target that appeared during pursuit. Participants pursued a moving row of circular frames and responded to a target presented within one of the frames. The results showed large RT differences between stimulus velocities up to 5°/s and 10°/s or above. RTs were faster for a target appearing in the pursuit direction than for one in the opposite direction. When an auditory precue was presented, the RTs during pursuit at 10°/s were faster with increases in the stimulus onset asynchrony (SOA) between the cue and the target. Furthermore, RTs were faster in the cued than in the uncued direction. These results not only support the idea that RTs during pursuit reflect the operation of attention, but also suggest that attention during pursuit can be shifted by the abrupt onset of a target stimulus and/or by prior information regarding the onset of a target stimulus.

Keywords Eye movements . Visual attention . Search . Reaction time methods

During smooth pursuit eye movement, spatial attention plays an important role in maintaining pursuit of a moving object by attenuating the effects of retinal image motion of the background (e.g., Kowler, van der Steen, Tamminga, & Collewijn, 1984). Without attention, the image motion of the background elicits optokinetic nystagmus (OKN), which acts to shift the observer's fixation in the direction of the background motion (opposite the direction of smooth pursuit), and pursuit performance deteriorates (Kerzel, Souto, & Ziegler, 2008). To examine the effects of attention on smooth pursuit directly, many studies have measured the performance of smooth pursuit by manipulating the attentional resources available for smooth pursuit and for secondary tasks (Chen, Holzman, & Nakayama, 2002; Hutton & Tegally, 2005) or by shifting the spatial location of attention (Kerzel et al., 2008; Khurana & Kowler, 1987; Madelain, Krauzlis, & Wallman, 2005). For example, Kerzel et al. measured pursuit gains during a dual task in which participants pursued a horizontally moving stimulus while discriminating target stimuli presented above or below the pursuit stimulus. To shift the participants' attention away from the pursuit stimulus, a cue concerning the target location was presented before the onset of the target. Kerzel et al. found that the pursuit gains during the dual task decreased after the onset of the cue or the onset of the target, suggesting that a spatial shift of attention from the pursuit stimulus impaired pursuit performance.

Although the results of many studies have indicated that spatial attention contributes to maintaining the smooth pursuit of a moving object, it is not fully understood how attention is spatially distributed during smooth pursuit. Studies using a reaction time (RT) task in which a target was presented along the pursuit trajectory have suggested that, during smooth pursuit, attention moves ahead of the pursued object along the trajectory (Tanaka, Yoshida, & Fukushima, 1998; van Donkelaar, 1999; van Donkelaar & Drew, 2002). For instance, van Donkelaar and Drew had participants view a display containing a central cross ("×") and eight peripheral circles, four placed horizontally on the right side of the cross, and four on the left. The centerto- center separation of the stimuli was 1° horizontally. The stimuli moved rightward horizontally at 3°, 5°, 10°, or 15°/s, and after a randomized period, one of the stimuli (the target) changed its shape (from an "×" to an "o," or vice versa). The participants' task was to pursue the cross accurately and to press a button when the target shape changed. The results showed that the RTs were faster for a target appearing on the right rather than the left side of the cross, particularly at high velocities (i. …

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