Human electrophysiological studies have found that the processing of faces and other objects differs reliably at Ϸ150 ms after stimulus onset, faces giving rise to a larger occipitotemporal field potential on the scalp, termed the N170. We hypothesize that visual expertise with nonface objects leads to the recruitment of early face-related categorization processes in the occipitotemporal cortex, as reflected by the N170. To test this hypothesis, the N170 in response to laterally presented faces was measured while subjects concurrently viewed centrally presented, novel, nonface objects (asymmetric ''Greebles''). The task was simply to report the side of the screen on which each face was presented. Five subjects were tested during three eventrelated potential sessions interspersed throughout a training protocol during which they became experts with Greebles. After expertise training, the N170 in response to faces was substantially decreased (Ϸ20% decrease in signal relative to that when subjects were novices) when concurrently processing a nonface object in the domain of expertise, but not when processing untrained objects of similar complexity. Thus, faces and nonface objects in a domain of expertise compete for early visual categorization processes in the occipitotemporal cortex.T he question of whether faces are processed by qualitatively different mechanisms from other object categories has been debated for more than three decades (1) and has been the focus of numerous studies (for reviews see refs. 2 and 3). Researchers still disagree on whether the neurofunctional mechanisms involved in face processing are domain-specific (4, 5) or are also recruited in identifying members of a visually homogeneous object category for which observers are visual experts (6, 7). Evidence in support of domain-specific face processing comes from the existence of neurons in the inferior temporal cortex of monkeys that respond preferentially to facial patterns. Such ''face cells'' begin to differentiate between faces and other stimuli between 100 and 200 ms (e.g., see ref. 8). At the systems level, at approximately the same latency, scalp electrophysiological recordings reveal a large occipitotemporal field potential in the lower ␣ range (7-10 Hz), termed the N170 (ref. 9) [termed the M170 in magnetoencephalography (MEG) studies; see ref. 10], that is larger in response to faces than to nonface object categories (9-12). The N170 is thought to originate from a network of regions in the inferior temporal cortex, including the fusiform gyrus and the middle, inferior, and superior temporal gyri (13, 14) (somewhat consistent with the localization of face-sensitive activity in neuroimaging; see refs. 15 and 16).At the same time, evidence from both behavioral (6, 17) and neuroimaging (18, 19) studies suggests that face-related processes can be recruited for nonface objects when observers are experts (7). However, neuroimaging methods such as functional MRI (fMRI) have poor temporal resolution, on the order of one to several seconds, beca...

Over the last ten years, Oosterhof and Todorov's valence-dominance model has emerged as the most prominent account of how people evaluate faces on social dimensions. In this model, two dimensions (valence and dominance) underpin social judgments of faces. Because this model has primarily been developed and tested in Western regions, it is unclear whether these findings apply to other regions. We addressed this question by replicating Oosterhof and Todorov's methodology across 11 world regions, 41 countries, and 11,570 participants. When we used Oosterhof and Todorov's original analysis strategy, the valence-dominance model generalized across regions. When we used an alternative methodology to allow for correlated dimensions we observed much less generalization. Collectively, these results suggest that, while the valence-dominance model generalizes very well across regions when dimensions are forced to be orthogonal, regional differences are revealed when we use different extraction methods, correlate and rotate the dimension reduction solution.

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The flashed face distortion (FFD) effect was coined by Tangen, Murphy, and Thompson (2011) in their second-place winner of the 2012 Best Illusion of the Year Contest. The FFD arises when people view various eye-aligned faces that are sequentially flashed in the visual periphery, and gradually the faces appear to be deformed and grotesque. In this functional magnetic resonance imaging (fMRI) study, participants were presented with four conditions: (a) one face pair changing only its illumination; (b) two and (c) three alternating face pairs; and (d) nonrepeated face pairs. Participants rated the magnitude of each illusion immediately after each block. Results showed that the receptive region of the early visual cortex (V1-V4), and category-selective areas such as the fusiform face area (FFA) and occipital face area (OFA), responded proportionally to the participants' rated FFD strength. A random-effects voxelwise analysis further revealed positively correlated areas (including the medial and superolateral frontal areas) and negatively correlated areas (including the precuneus, postcentral gyrus, right insula, and bilateral middle frontal gyri) with respect to participants' ratings. Time series correlations among these nine ROIs (four positive and five negative) indicated that most participants showed a clustering of the two separate ROI types. Exploratory factor analysis (EFA) also demonstrated the segregation of the positive and negative ROIs; additionally, two subsystems were identified within the negative ROIs. These results suggest that the FFD is mediated by at least two networks: one that is likely responsible for perception and another that is likely responsible for subjective feelings and engagement.

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