Frontiers in Human Neuroscience (Mar 2011)
Why some faces won’t be remembered: Brain potentials illuminate successful versus unsuccessful encoding for same-race and other-race faces
Abstract
Memory is often less accurate for faces from another racial group than for faces from one's own racial group. The mechanisms underlying this phenomenon are a topic of active debate. Contemporary theories invoke factors such as inferior expertise with faces from other racial groups and an encoding emphasis on race-specifying information. We investigated neural mechanisms of this memory bias by recording event-related potentials while participants attempted to memorize same-race and other-race faces. Brain potentials at encoding were compared as a function of successful versus unsuccessful recognition on a subsequent memory test. Late positive amplitudes predicted subsequent memory for same-race faces and, to a lesser extent, for other-race faces. By contrast, the amplitudes of earlier frontocentral N200 potentials and occipito-temporal P2 potentials were larger for later-remembered relative to later-forgotten other-race faces. Furthermore, N200 and P2 amplitudes were larger for other-race faces with features considered atypical of that race relative to faces that were race-stereotypical (according to a consensus from a large group of other participants). In keeping with previous reports, we infer that these earlier potentials index the processing of unique or individuating facial information, which is key to remembering a face. Individuation may tend to be uniformly high for same-race faces but lower and less reliable for other-race faces. Individuation may also be more readily applied for other-race faces that appear less stereotypical. These electrophysiological measures thus provide novel evidence that poorer memory for other-race faces stems from encoding that is inadequate because it fails to emphasize individuating information.
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