Effects of stimulus inversion on the attentional selection and working memory encoding of individual faces

Effects of face inversion have been widely demonstrated behaviourally. Face inversion is known to impair the speed and accuracy of face recognition (e.g., Yin, 1969). Event-related brain potential (ERPs) studies have shown that face inversion also affects the perceptual encoding of faces, as reflected by a delay and amplitude increase of the face-sensitive N170 component (e.g., Bentin et al., 1996). However, the impact of face inversion on the attentional selection and encoding of individual faces in visual working memory has not yet been investigated with on-line electrophysiological measures. In the present study, we recorded ERPs in a task that required participants to report the presence or absence of a learned previously unfamiliar target face that could appear together with a non-target face in a bilateral search array. In different trials, face pairs were presented either in an upright or upside-down orientation. A robust face inversion effect was observed for target-present responses, which were delayed by approximately 50 ms for upside-down faces. Face inversion also affected the N2pc component (reflecting the attentional selection of a target face) and the subsequent sustained contralateral negativity (SPCN, which marks the activation of a working memory representation of the selected face). The N2pc emerged approximately 15 ms later for inverted as compared to upright faces, demonstrating that inversion delays the allocation of attention to target faces. The SPCN was attenuated for inverted as compared to upright target faces, suggesting that working memory representations were activated less strongly by inverted faces. This is in line with recent behavioural evidence that face inversion reduces the precision of visual face memory (Lorenc et al., 2014). These results provide novel electrophysiological evidence for the impact of face inversion on speed and efficiency of visual attention during the selection and identification of individual faces. Meeting abstract presented at VSS 2015