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David Carmel, Anna Khesin, Marisa Carrasco; Attentional facilitation of perceptual learning without awareness. Journal of Vision 2010;10(7):357. doi: 10.1167/10.7.357.
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© ARVO (1962-2015); The Authors (2016-present)
Background: Perceptual learning (PL) - practice-induced improvement in perceptual task performance - is a manifestation of adult neural plasticity. Endogenous (voluntary) attention facilitates PL, but some have argued that attention plays no essential role in PL because PL can occur even when observers are unaware of the “trained” stimulus. We therefore asked whether manipulating attention to stimuli observers remain unaware of would affect PL of those stimuli.
Method: We manipulated endogenous (voluntary) spatial attention to assess whether PL would occur at attended and unattended locations, suppressing trained stimuli from awareness using continuous flash suppression (CFS), a strong form of binocular rivalry where monocular stimuli are rendered invisible by dynamic displays presented to the other eye. During 10 training sessions, observers viewed a CFS display and performed an attentional task on stimuli presented to the dominant eye. This task required attention to stimuli presented in two diagonally-located corners of the display, while ignoring stimuli in the other two corners. Concurrently, the suppressed eye was shown Gabors (the trained stimuli) at retinal locations corresponding to both attended and unattended locations. To equate the amount of practice in directing attention to all locations, on half of each session's blocks the dominant eye's attended and unattended locations were switched and no Gabors were presented to the suppressed eye. Before and after the training sessions, we measured contrast thresholds (without CFS) for trained stimuli at attended and unattended locations. To assess learning specificity, we also measured thresholds to “untrained” Gabors with orthogonal orientations.
Results and conclusion: Performance for trained stimuli at attended locations improved dramatically. As these stimuli were suppressed by CFS during training, this finding indicates that attention can facilitate PL without awareness. Smaller improvements were found for the other stimulus/location combinations, indicating that practice in directing spatial attention can also improve performance.
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