Ingroup categorization affects the structural encoding of other-race faces: Evidence from the N170 event-related potential

Abstract

The current research examined the influence of ingroup/outgroup categorization on brain event-related potentials measured during perceptual processing of own- and other-race faces. White participants performed a sequential matching task with upright and inverted faces belonging either to their own race (White) or to another race (Black) and affiliated with either their own university or another university by a preceding visual prime. Results demonstrated that the right-lateralized N170 component evoked by test faces was modulated by race and by social category: the N170 to own-race faces showed a larger inversion effect (i.e., latency delay for inverted faces) when the faces were categorized as other-university rather than own-university members; the N170 to other-race faces showed no modulation of its inversion effect by university affiliation. These results suggest that neural correlates of structural face encoding (as evidenced by the N170 inversion effects) can be modulated by both visual (racial) and nonvisual (social) ingroup/outgroup status.

Keywords:

• Other-race effect
• Cross-race effect
• Own-race bias
• Ingroup/outgroup categorization
• Configural/holistic processing
• Structural encoding
• N170 event-related potential

Notes

¹  We recognize that there is an ongoing debate as to the nature of “configural” face processing and that many researchers prefer the term “holistic.” We use the term “configural” in this paper because of its compatibility with the language of the Categorization–Individuation Model.

²  We also examined the P100 and P200 components, seeking to determine whether own-university/other-university categorization would affect the initial processing of facial features (P100) and/or recruit slower-acting attentional processes (P200). The results were inconclusive; this may not be surprising, given the less consistent relationship of these components to inversion effects and own- versus other-race status shown in past research. For the reader’s interest, however, we report the results for P100 and P200 in Supplementary Materials.

³  Our primary analyses focused on the ERPs averaged across “same” and “different” trials and across hemispheres. However, as behavioral performance in our task was influenced in a general way by response type, and because same/different judgments can affect ERP components across a wide spatio-temporal range (e.g., Barrett, Rugg, & Perrett, 1988), we conducted parallel peak analyses on “same” and “different” trials separately through Race × University × Orientation ANOVAs. These analyses are presented in in Supplementary Materials.