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Michael Jigo, Marisa Carrasco; The effect of exogenous spatial attention on the contrast sensitivity function across eccentricity. Journal of Vision 2019;19(10):100c. doi: https://doi.org/10.1167/19.10.100c.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: Covert exogenous spatial attention, the stimulus-driven orienting response to a salient spatial location, reflexively and transiently enhances the visual system’s contrast sensitivity. Previous reports demonstrate that contrast sensitivity is enhanced across a wide range of spatial frequencies and separately across eccentricities. However, how the effect of attention varies as a function of both spatial frequency and eccentricity has yet to be explored systematically. Here, we addressed this gap by parametrically manipulating contrast, eccentricity, spatial frequency, and attention in a single study with the same observers. Methods: Contrast sensitivity was measured with a 2AFC orientation discrimination task. Sinusoidal gratings of 6 possible spatial frequencies (0.5–11 cpd) were presented at 4 possible eccentricities (0–12 dva) along the horizontal meridian and were tilted ±45°. Each grating was displayed at 5 possible contrast levels, encompassing the participant’s dynamic range for each spatial frequency and eccentricity condition. Exogenous spatial attention was manipulated with valid (focal) pre-cues and was compared to a neutral condition during which pre-cues were distributed across all possible target locations. Contrast thresholds were estimated for each spatial frequency, eccentricity, and cueing condition. Results: Contrast sensitivity functions (CSFs; threshold-1 as a function of spatial frequency) were estimated for each cueing condition and eccentricity. CSFs were bandpass at each eccentricity, peaking at progressively lower spatial frequencies as eccentricity increased. Attention enhanced sensitivity across conditions. Overall, attention preferentially enhanced sensitivity to spatial frequencies 1–2 octaves above the preferred spatial frequency in the neutral condition. Conclusion: Exogenous spatial attention operates similarly across eccentricity. Attention generally enhances sensitivity to higher spatial frequencies, relative to the preferred spatial frequency at each eccentricity. Our results highlight how the visual system reflexively reshapes SF selectivity.
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