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Soki Nakamura, Ikuya Murakami; Time compression in an unadapted region after adaptation to a moving surround. Journal of Vision 2015;15(12):810. doi: 10.1167/15.12.810.
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© ARVO (1962-2015); The Authors (2016-present)
After adaptation to a rapidly moving grating, a drifting grating placed at the adapted region appears to last shorter than its actual duration (“adaptation-based time compression”, Johnston et al 2006). This effect occurs retinotopically (Bruno et al 2010), though there might be some spatiotopic component as well (Burr et al 2007). The spatial tuning of this effect has been reported to have a narrow spatial window (Ayhan et al 2009), such that the effect of adaptation never transfers to unadapted locations in its vicinity. However, previous testing methods of spatial interactions should be revised so as to maximize potential effects of adaptation by overwhelming a test stimulus with a large enough adaptor completely surrounding the test region. To this end, we used a concentric configuration: centered at 8° eccentricity, a rapidly moving (10 Hz) sinusoidal adapting grating that alternated its direction every second occupied the annular region (outer diam 11.4°, inner 7.6°) for 32-s initial and 8-s top-up adaptation periods, each followed by a drifting (10 Hz) sinusoidal grating (diam 5.7°) presented as the test stimulus only within the central region for 0.6 s. In the opposite (left) hemifield, we also presented a reference stimulus, which was also a sinusoidal grating with the same parameters as the test except that the motion direction was opposite and that the duration was variable (0.3–0.9 s). Observers had to judge which stimulus lasted longer. Even though the test stimulus was located at a region with no former adaptation, we found a robust time compression (~10%), which was sometimes as strong as the effect obtained with retinotopic adaptation. Our results indicate some involvement of higher-order motion processing mechanisms that can deal with spatial interactions over a considerable space constant, although our findings do not necessarily refute the hypothesis of the magnocellular pathway’s contribution.
Meeting abstract presented at VSS 2015
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