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Isamu Motoyoshi; Attentional modulation of the temporal contrast sensitivity. Journal of Vision 2010;10(7):298. doi: 10.1167/10.7.298.
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© ARVO (1962-2015); The Authors (2016-present)
Recent psychophysical studies show that attention not only raises the sensitivity for visual targets, but also enhances the spatial resolution. On the other hand, little is known about the effect of attention on the temporal property. A few studies suggest that attention rather declines the temporal resolution for suprathreshold stimuli (e.g., Yeshurun & Levy, 2003), but it is unclear if this reflects changes in the general properties of the visual system. In the present study we examined the effect of attention on the contrast sensitivity over a range of temporal frequencies. Eight observers were asked to detect a drifting grating (2.2 c/deg, 0 to 40 Hz,) presented gradually at one of eight possible locations (4.6 deg eccentricity) on a uniform background while performing a letter recognition task in the central RSVP display (dual task). The results showed that the removal of attention by the central task largely declined the contrast sensitivity, particularly to low temporal frequencies, resulting in the band-pass shaped CSF. The sensitivity ratio (90% correct response) between the single and dual task modes was 7.2 for the static grating, far greater than those obtained with flashed gratings (∼1.5; e.g., Carrasco, Talgar & Eckstein, 2000), but was 1.2 for the drifting grating of 40 Hz. A system analysis revealed that the removal of attention reduced the overall gain and increased the transient factor of the CSF, but little affected the cut-off temporal frequency. These results support the notion that attention extensively modulates the sensitivities for sustained, but not transient, visual inputs.
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