Sudden and gradual presentation of distractor objects: differential interference effects

Abstract

In solving the selection-for-action problem, it is believed that attentional mechanisms enable dominance of target over non-target objects. However, under some conditions, information from non-target objects "interferes" with the action to a relevant target. We investigated the possibility that this interference may result when the irrelevant object activates a specific subset of visuomotor pathways. Participants reached to grasp three-dimensional stimuli while actively attending to a nearby flanker object. The means by which the flanker was presented was manipulated. This relevant object was illuminated either abruptly or gradually. The parvocellular pathway in early visual processing is equally activated in both conditions. The magnocellular pathway is strongly activated by abrupt presentation and weakly activated with gradual presentation of the flanker object. Kinematics of the reach-to-grasp action to the target showed signs of interference only in the sudden illumination condition. This suggests a dissociation between dorsal and ventral cortical streams in terms of relevance for action. Our data suggests that this effect is not due to early visual-pathway differences, but instead reveals a property of a transient object-based visual attention mechanism.

Selective attention contributes to global processing in vision

“…Experiments have produced varying estimates of the maximum radius for processing enhancement, but this is perhaps not surprising given the dynamic nature of the system under examination. Experiments comparing the effects of sustained and transient cues (Castiello, Badcock, & Bennett, 1999;Nakayama & Mackeben, 1989) have however suggested that attention itself can be dissociated into sustained and transient components. The transient component, it is suggested, is not subject to voluntary control and the 'line motion' illusion has been used to show that it supersedes the voluntary, sustained component of attention for around 300 ms (Hikosaka et al, 1996).…”

The eyes like their targets on a stable background

“…The emphasis on change continues throughout the visual system. For example, on a level much higher than the photoreceptors, the focus of (covert and overt) visual attention is very effectively drawn by abrupt changes in stimuli (Castiello, Badcock, & Bennett, 1999;Todd & Van Gelder, 1979;Yantis & Jonides, 1990).…”