Individual differences in metacontrast masking are reflected by activation of distinct fronto-parietal networks T Albrecht, D Krüger, U Mattler |
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Georg-Elias-Müller Institute for Psychology, Georg-August University Göttingen, Germany
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| In metacontrast masking the visibility of a briefly presented target stimulus is reduced by a subsequent masking stimulus whose contours fit snugly around the contours of the target. In several recent studies we have shown that observers differ qualitatively in the time course of masked target discrimination. Whereas one type of participants shows increasing discrimination performance with increasing stimulus onset asynchrony (SOA) between target and mask (Type-A observers), another type of participants exhibit decreasing discrimination performance with increasing SOA (Type-B observers). These differences in discrimination performance are complemented by differences in subjective phenomenology and the use of different perceptual cues. Here we present a neuroimaging study in which we aimed to localize those brain areas that reflect the time courses of behavioral masking functions. To this end we tested for brain activations that closely follow the behavioral masking functions of either Type-A or Type-B observers. Results show that activation in bilateral putamen correlates with behavioral masking functions regardless of observer type. Frontal and parietal brain regions including the insula, the inferior frontal gyrus and the precuneus show type-specific correlations. Overall, findings suggest that individual differences in metacontrast masking reflect differences in attentional mechanisms and higher-level vision processes. |
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