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Peter Bex, Keith Langley; The visual system discounts temporal artifacts introduced by its eye movements during reading. Journal of Vision 2009;9(8):1091. doi: 10.1167/9.8.1091.
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© ARVO (1962-2015); The Authors (2016-present)
Objective: Saccadic eye movements abruptly update the retinal image every 200 msec or so during reading. We examine how these dynamic images affect visual sensitivity with an adaptation paradigm.
Methods: Text from common novels was presented on a computer screen in c.10 second passages. Observers either actively read the text or passively fixated a stationary point while the text was updated at 0.25, 1 or 4 times typical reading speeds. Between passages, observers detected spatio-temporal frequency band-pass filtered noise in a 2AFC task with feedback.
Results: Contrast detection thresholds were elevated following the presentation of text, but less so after active reading than passive text viewing. For spatial frequency, there were two peaks that corresponded approximately to the periodicity of lines and letters. For temporal frequency, threshold elevations reciprocated the temporal contrast sensitivity function, with minimum threshold elevations around 9.0 Hz.
Conclusions: The results are consistent with adaptive changes in contrast sensitivity that arise from a second-order model of temporal processing in which the 1/? temporal amplitude spectrum attributed to natural scenes is itself modulated by the expected dynamics of eye movements.
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