Neuropsychologia 49 (2011) 1154–1161 Contents lists available at ScienceDirect Neuropsychologia journal homepage: www.elsevier.com/locate/neuropsychologia The time course of implicit processing of facial features: An event-related potential study F. Pesciarelli a,∗ , M. Sarlo b , I. Leo c a Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100 Modena, Italy b Department of General Psychology, University of Padova, Padova, Italy c Department of Developmental Psychology, University of Padova, Padova, Italy article info Article history: Received 24 August 2010 Received in revised form 28 January 2011 Accepted 2 February 2011 Available online 17 February 2011 Keywords: Event-related potentials Face processing Masked priming abstract In this study, we used ERPs to investigate the time course of implicit face processing. More specifically, we utilized a masked priming paradigm to investigate implicit processing of the eyes and mouth in upright and inverted faces, using a prime duration of 33 ms. Two types of prime–target pairs were used: (1) congruent (e.g., open eyes only in both prime and target); (2) incongruent (e.g., open eyes only in prime and open mouth only in target). The identity of the faces changed between prime and target. Participants pressed one button to indicate whether the target face’s mouth was open, and another if the eyes were open. The behavioral results indicated a congruent priming effect for upright but not for inverted faces. The ERP results indicated a face orientation effect across all ERP components studied (P1, N1, P2, N170, N2, P3) starting at about 80 ms, and a congruency/priming effect on late components (N2, P3), starting at about 200 ms. The functional significance of these ERP effects is discussed in relation to unconscious perception and configural face processing. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Despite recent theoretical and experimental contributions to the study of face processing, questions about the cognitive mech- anisms and the neural substrates subtending the perception of the information in the face are still under debate. Adults are experts in processing faces (e.g., Diamond & Carey, 1986) and can recognize thousands of individual faces rapidly and accurately (e.g., Bahrick, Bahrick, & Wittlinger, 1975). This ability is attributed to enhanced sensitivity to configural information in faces. Configural process- ing of faces involves processing not just the shapes of individual features (featural or component information) but also the relations among them (relational or configural information) (e.g., Maurer, Le Grand, & Mondloch, 2002). Relative to upright faces, recognizing inverted faces is surprisingly poor, with the decrement far larger than it is for shoes or houses. Indeed, the face inversion effect, much poorer accuracy and longer reaction times when faces are upside down, has been taken as diagnostic of configural processing. In accordance with the old model of Diamond and Carey (1986), Maurer et al. (2002) have recently suggested that face process- ing involves three levels of configural processing: an initial stage that encodes the first-order relational information (which refers to qualitative spatial relations among facial features); a second holis- ∗ Corresponding author. Tel.: +39 059 2055340; fax: +39 059 2055363. E-mail address: francesca.pesciarelli@unimore.it (F. Pesciarelli). tic stage that integrates facial features into a whole or a Gestalt, thus rendering individual features less accessible; and a third stage that encodes the second-order relational information (which refers to fine spatial relations between features). The difference between the first two stages is rather subtle because when adults detect the first-order relations of a face, they tend to process the stimu- lus as a Gestalt (e.g., Maurer et al., 2002). In contrast, recognition of a specific face occurs subsequently on the basis of the second- order relational information (e.g., Carey & Diamond, 1977; Freire & Lee, 2001). Detecting and recognizing faces are two important com- ponents of face processing. Current cognitive (e.g., Bruce & Young, 1986) and neural (e.g., Haxby, Hoffman, & Gobbini, 2000) models of face processing propose that face recognition is a sequential pro- cess in which an initial stage of structural encoding is necessary. Detecting a facial configuration is fast and efficient and is facili- tated by the fact that all faces share the same first-order relational features, with two eyes above a nose, which is above a mouth, lead- ing to holistic processing (e.g., Diamond & Carey, 1986). Adults have a remarkable ability to detect faces among a sample of other visual stimuli on the basis of first-order relational information, even in the absence of normal facial features (e.g., Moscovitch, Winocur, & Behrmann, 1997). The most convincing demonstration that when adults detect the first-order relations of a face they tend to process the stimulus as a Gestalt is the part-whole effect (Farah, Wilson, Drain, & Tanaka, 1998; Tanaka & Farah, 1993). Accuracy in dis- criminating individual face parts is higher when the entire face is presented than when the parts are presented in isolation, whereas 0028-3932/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.neuropsychologia.2011.02.003