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Simen Hagen, James Tanaka; Examining within-category discrimination of faces and objects of expertise.. Journal of Vision 2018;18(10):394. doi: https://doi.org/10.1167/18.10.394.
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© ARVO (1962-2015); The Authors (2016-present)
Object experts quickly and accurately discriminate objects within their domain of expertise. The current study used a novel and implicit visual discrimination paradigm coupled with electroencephalography – Fast Periodic Visual Stimulation – to examine whether within-category discrimination of face and non-face objects of expertise rely on shared visual discrimination mechanisms. Bird experts and novices were presented with sequences of the same object image of a family-level bird (Robin), species-level bird (Purple Finch), or face (Face A) at a periodic rate of six images per second (6.00 Hz), with size varying randomly at every cycle to restrict adaptation to areas sensitive to object discrimination. A different within-category "oddball" family-level bird (Finch), species-level bird (Cassin's Finch) or face (Face B) was interleaved with the base image at every 5th cycle (1.20 Hz). Thus, a differential response at 1.20 Hz is an index of within-category discriminability between the base- and oddball-objects. We reasoned that discriminability of one object domain should be correlated at the participant level with the discriminability of another object domain if they share common visual discrimination mechanisms. The results showed a robust base signal (6.00 Hz, medial-occipital channels) and discrimination signal (1.20 Hz, occipito-temporal channels) that did not differ as a function of group by object domain. At the participant level, the base signal (6.00 Hz, medial-occipital channels) for all object categories positively correlated in both experts and novices. Importantly, the discrimination signal (1.20 Hz, occipito-temporal channels) for face and birds correlated in experts, but no pattern of correlations was found in novices. Moreover, family- and species-level birds correlated in both experts and novices. This indicates that the discrimination mechanisms for faces and birds were shared in the experts, but not in the novices. Overall, this suggests that face and non-face objects of expertise share visual discrimination mechanisms.
Meeting abstract presented at VSS 2018
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