Signatures of emotional face processing measured by event-related potentials in 7-month-old infants

Abstract

The ability to distinguish facial emotions emerges in infancy. Although this ability has been shown to emerge between 5 and 7 months of age, the literature is less clear regarding the extent to which neural correlates of perception and attention play a role in processing of specific emotions. This study's main goal was to examine this question among infants. To this end, we presented angry, fearful, and happy faces to 7-month-old infants (N = 107, 51% female) while recording event-related brain potentials. The perceptual N290 component showed a heightened response for fearful and happy relative to angry faces. Attentional processing, indexed by the P400, showed some evidence of a heightened response for fearful relative to happy and angry faces. We did not observe robust differences by emotion in the negative central (Nc) component, although trends were consistent with previous work suggesting a heightened response to negatively valenced expressions. Results suggest that perceptual (N290) and attentional (P400) processing is sensitive to emotions in faces, but these processes do not provide evidence for a fear-specific bias across components.

Keywords: N290; Nc; P400; emotions; face processing; infant ERP.

Figure 1.. Task Progression.

Figure 2.. Location of Electrodes Corresponding to Each Region.

Note. Pink circles represent the channels used for the broad analysis of the N290 and P400. The pink shaded channels (38, 39-O2, 43, 44-P8) were used for the focused analysis of the N290 and P400. Green circles identify channels used to for the broad analysis of the Nc. The subset of green shaded channels (4, 7, 16, 21, 41, 51, 54) represent those used for the focused analysis of the Nc.

Figure 3.. Visualization of ERP Results.

Note. A) Grand average scalp topographical response for time windows characterizing the N290 (left) and P400/Nc (right) across electrodes of interest and emotion categories. White dots represent approximate scalp location of posterior electrodes of interest used for focused ERP analysis of the N290 and P400. Black dots represent approximate scalp location of fronto-central electrodes of interest used for focused ERP analysis of Nc. B) Event-related potential waveforms for the focused analysis of emotion in faces over posterior and fronto-central scalp sites. Shaded grey regions represent approximate time windows of interest used for analyses C) Average ERP response to fearful (F), angry (A), and happy (H) faces for each component of interest in focused regions. An * indicates a significant difference between emotion conditions in bar graphs. Note that values for N290 represent corrected peak amplitudes, whereas both mean and corrected peak amplitudes for P400 are shown. Values for Nc are mean amplitudes (see text for further details). Error bars represent −/+ 1 Standard Error.