Attention and Oculomotor Control: Attentional Resolution

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DESCRIPTION (provided by applicant): There is a great deal of evidence that eye movements and attention are linked. However, evidence regarding the nature of the link is sometimes contradictory and lacking. Specification of the relationship between the two systems would allow us to consider attention, which is a poorly specified construct, within the relatively concrete and neurally well understood domain of eye movements. We propose to investigate the relationship between attention and eye movements within a new domain to help resolve some of the contradictions and fill in some of the gaps of knowledge. Specifically, we seek to understand the relationship between attention and eye movements through an investigation of attentional resolution, which is the precision with which one can discretely move attention among closely spaced items. Attentional resolution is remarkably coarse given the precision with which people can perceive simply that there are multiple items present. Eye movements, it seems, may be limited in a similar way; counting items in a closely spaced display, for example, is no easier when one is allowed to fixate the items than when one must rely on attention only. Together, these observations suggest that oculomotor limitations may determine at least some attentional limitations (or vice versa), thereby providing a specific link and domain of inquiry between the two systems. We will begin by comparing attentional resolution to saccadic resolution, which is the precision with which people can move their eyes to individual items. We hypothesize that the limits of attentional control are imposed by the limits of saccadic control, and therefore that attentional resolution will be indiscriminable from or coarser than saccadic resolution. We will then relate the instability of ocular fixation to the coarseness of attentional resolution. We hypothesize that the limitations of attentional resolution are at least partly determined by the spatial uncertainty that is created by ocular jitter during fixation, and therefore that attentional resolution will be finer when that jitter is eliminated by optically stabilizing the display. Finally, we will assess how experimental manipulations that are known to affect saccadic behavior affect attentional resolution. We hypothesize, for example, that transient adaptation of the saccadic system will transfer to the attentional control system and alter observers' attentional resolution.