Abstract
One of the most studied face-sensitive event-related potential is the N170. Multiple studies have already explored the specific visual information driving this component’s response. For instance, the N170 has been linked to processing of the eye region and to the integration of diagnostic information (Schyns et al., 2007). However, little is known about what information elicits the N250, another component associated with face identification, more specifically, transient activation of stored face representations (Tanaka et al., 2006). To have a better understanding of this, we recorded scalp electroencephalography (EEG; 64 channels) from four participants while they each completed 12,000 trials (48,000 trials total) of a ten-identity face recognition task. Facial information was randomly sampled with Bubbles (Gosselin & Schyns, 2002), which applies Gaussian windows independently to five non-overlapping spatial frequency (SF) bands (one octave width). At each time point and for each SF band, data from channels PO7 and PO8 were submitted to classification image analysis to measure the association between facial information and EEG voltage. As expected from previous studies, results revealed an association between N170 amplitude and presence of the contralateral eye in every SF band (Rousselet et al., 2014). In addition, N250 amplitude was also linked with presence of the contralateral eye at high (32-64 cpf) and intermediate (4-8 cpf) SFs, but not at lower (2-4 cpf) SFs. Interestingly, the eye region was also found to be the most diagnostic feature for face identification in high to intermediate SFs (Butler et al., 2010). Moreover, the eye region is also rich in horizontal structure (Daking & Watt, 2009), an orientation band that has been both associated with face recognition and the N250 (Hashemi et al., 2018). Together, these results suggest that diagnostic information, especially from the eyes, plays a crucial role in retrieval and activation of stored face representations.