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Alissa Winkler, Susana Marcos, Stephen Engel, Michael Webster; Dynamics of blur adaptation. Journal of Vision 2015;15(12):27. doi: https://doi.org/10.1167/15.12.27.
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© ARVO (1962-2015); The Authors (2016-present)
Adaptating to blurred images changes visual performance in two ways: perceived focus of images alters almost immediately, and, more gradually, visual acuity improves. Do these aftereffects reflect changes in the strength of the same controlling mechanism over different durations, or are perceived blur and visual acuity controlled by separate adaptive mechanisms? To answer this question, we tracked the magnitude of blur aftereffects over periods up to 2 hours. Observers adapted by watching a film that was blurred by filtering the log amplitude spectrum to have a steeper slope (-0.5) but the same rms contrast as each original frame. The film was a documentary portraying natural outdoor scenes and was shown in grayscale on a calibrated monitor. Test trials were interleaved with the film at 7.5 sec intervals and alternated between a single static grayscale image of a natural textured scene with varying spectral slope, or a Landolt C pattern that varied in size. A quest routine was used to track perceived blur as the image slope that appeared in focus (neither too blurred nor too sharp) and a one-up, one-down staircase tracked the acuity limit for the Landolt C target (minimum angle of resolution). Blur aftereffects were strong and built up rapidly, but asymptoted after a few minutes and thus showed little increase at longer durations. In contrast, for our conditions acuity was not affected by the adaptation and thus did not systematically vary across the session. Our results indicate that the potential emergence of long-term acuity changes with blur adaptation may not coincide with corresponding changes in perceived image focus over time. This difference in timecourses suggests that dissociable mechanisms may underly the different aftereffects.
Meeting abstract presented at VSS 2015
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