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Nicole D. Anderson, Hugh R. Wilson; Behavioural tuning of face-selective neural populations. Journal of Vision 2006;6(6):277. doi: 10.1167/6.6.277.
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© ARVO (1962-2015); The Authors (2016-present)
Recent fMRI evidence demonstrates that face-selective mechanisms are tuned to face identity in a manner consistent with geometric face space. We evaluated the spatiotemporal properties of identity tuning for synthetic faces using a behavioural reverse correlation technique proposed by Ringach (1998). With this technique, different faces were rapidly (∼80ms) flashed on the screen and subjects were required to respond when a target face was presented as quickly as possible. Spatial and temporal tuning were assessed by correlating the probability that a particular stimulus was presented in the recent history of a subject's response. Spatiotemporal tuning plots were measured for face detection (detection of an intact face in the presence of scrambled faces) and for face identification (detection of one face identity in the presence of other identities). When asked to detect an intact face, subjects were most likely to respond on average 497.4 ms after an intact face was presented in the stimulus history. When asked to detect a specific identity, on the other hand, subjects were most likely to respond on average 587.9 ms after the target identity was presented. This temporal response difference is inconsistent with previous research demonstrating similar reaction times for face detection and identification. Moreover, subjects tended to be less likely to respond when a geometrically opposite ‘anti-face’ was presented at the same point in the stimulus history. These results suggest that inhibitory mechanisms may contribute to the tuning of face-selective mechanisms, similar in principle to opponent mechanisms that are observed in the orientation domain.
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