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Robert Faludi, Laurence T. Maloney, Marisa Carrasco; Visual Performance Fields and Motor Responses. Journal of Vision 2004;4(8):447. doi: 10.1167/4.8.447.
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© ARVO (1962-2015); The Authors (2016-present)
Background: Contrast sensitivity and spatial resolution are not homogenous across the visual field, even at iso-eccentric locations. Results for typical observers in these tasks exhibit both a horizontal-vertical anisotropy (HVA) and a vertical meridian asymmetry (VMA) known as performance fields. Transient attention has been found to improve discriminability at all spatial locations to a similar degree, leaving spatial asymmetries unaffected (Carrasco et al., 2000; Talgar & Carrasco, 2002). Here we compare performance fields generated using keyboard responses with the results from a more natural motor response—hand movements to directly touch stimuli displayed on the computer monitor. Methods: Observers performed a 2AFC task in which they were asked to judge whether the target (2°, 4 cpd tilted Gabor) was present or absent. The target stimulus appeared randomly at 1 of 8 cardinal and inter-cardinal locations, at 9° eccentricity, with distracters occupying the non-target locations. To direct attention, a cue appeared adjacent to the potential target location for 67 ms, 54 ms before a target/distracter stimulus was presented for 54 ms. This timing precluded eye movements. Responses were made by standard keyboard response or touch screen localization. For keyboard responses, observers pressed one of two buttons. In the touch screen task, observers touched the target location on the monitor, or fixation if no target was perceived. Results: HVA and VMA were found in both keyboard and direct motor system responses. Both response methods showed faster reaction time and greater accuracy with attention. Accuracy increased for direct and keyboard responses more in the East & West locations, compared to the North & South locations, and in the South compared to the North. The results indicate that motor responses to visual stimuli reflect both visual performance asymmetry and anisotropy. Implications for research methodology and human factors applications will be discussed.
Grant BCS-9910734/HCP from the National Science Foundation; Grant EY08266 from the National Institute of Health; Grant RG0109/1999-B from the Human Frontiers Science Program.
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