The role of visual attention in saccadic eye movements

Abstract

The relationship between saccadic eye movements and covert orienting of visual spatial attention was investigated in two experiments. Inthe first experiment, subjects were required to make a saccade to a specified location while also detecting a visual target presented just prior to the eye movement. Detection accuracy was highest when the location of the target coincided with the location of the saccade, suggesting that subjects use spatial attention in the programming and/or execution of saccadic eye movements. In the second experiment, subjects were explicitly directed to attend to a particular location and to make a saccade to the same location or to a different one. Superior target detection occurred at the saccade location regardless of attention instructions. This finding shows that subjects cannot move their eyes to one location and attend to a different one. The results of these experiments suggest that visuospatial attention is an important mechanism in generating voluntary saccadic eye movements.We selectively explore the visual panorama by means of fixations lasting about a quarter of a second interspersed with rapid changes of eye position lasting about 50 msec. The pattern of these fixations and the choice of where to send the eye next is not random but instead appears to be guided . Yarbus (1967), for example, pointed out that the pattern of eye fixations that a given observer produces is influenced by properties ofthe scene as well as the goals and interests of the perceiver. Examples of this principle have been provided by many demonstrations that fixations in reading are influenced by properties ofthe text, such as word length (Rayner, 1975), as well as knowledge of the reader in the form of expectations, text schemas, and so on (Just & Carpenter, 1987;Kowler, 1991).What is the mechanism that chooses the destination of each subsequent saccade? A likely candidate is the spatial attention system, a mechanism that can operate within a fixation to selectively process information from different locations (Eriksen & Hoffman, 1973, 1974Hoffman, 1975;Hoffman & Nelson, 1981;Posner, 1980;Posner, Nissen, & Ogden, 1978). Allocating attention to a position in space results in faster and more accurate processing of luminance and form information in a region of space surrounding that location (Bash inski & Bacharach, 1980;Downing, 1988;Hawkins et al., 1990;Hoffman & Nelson, ). In addition to enhancing perceptual processing, attention may also be important in guiding "action systems," such as reaching (Allport, 1987(Allport, , 1991. Because shifts of attention can occur much faster than changes in eye position (Hoffman, 1975), spatial attention can be used during one fixation to choose the location for the followingfixation.Indirect support for the claim that attention guides saccades is provided by a large literature showing that shapes are perceived faster and more accurately when they are near the target ofan upcoming saccade. For example, MeConkie and Rayner (1975) have used the moving-window paradigm t...

The apolipoprotein E gene, attention, and brain function.

“…This is not surprising given that the parietal cortical areas mediating shifts of covert attention and eye movements overlap (Anderson et al, 1994;Corbetta et al, 1998) and that cognitive studies have also shown links between covert and overt attention (Hoffman, 1998;Klein, Kingstone, & Pontefract, 1992). Scinto et al found that individuals with AD were less accurate and slowed in shifting their gaze between a central fixation point and a target dot presented in sequence at peripheral locations.…”

How laminar frontal cortex and basal ganglia circuits interact to control planned and reactive saccades

“…First, attention is directed toward the target of a saccade prior to saccade initiation (Hoffman and Subramanian, 1995). This enables the FEF to wrest attention away from physically prepotent stimuli and instead focus attention on a motivationally salient saccade target, by means of excitatory FEF-PPC projections ( Figure I).…”

Crossmodal coupling of oculomotor control and spatial attention in vision and audition

“…Typically, saccades are preceded by covert shifts of visual attention to the target location (Deubel and Schneider 1996;Hoffman and Subramaniam 1995;Kowler et al 1995) and can enhance hearing performance at that location prior to the movement (Rorden and Driver 1999). In turn, shifts of covert attention were linked to saccade preparation (Kustov and Robinson 1996;Rizzolatti et al 1987Rizzolatti et al , 1994) but do not necessarily initiate saccades, i.e., we can attend to locations in the visual periphery without large eye movements.…”