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Person Categorization

Subject Area General, Cognitive and Mathematical Psychology
Term from 2007 to 2015
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 38787548
 
Final Report Year 2016

Final Report Abstract

This project examined both the neural and perceptual bases of categorizing faces according to age, sex, and ethnic group. The studies were motivated by recent socio-cognitive approaches, which assume the categorization of faces into social in- versus out-groups as the basis for both faster categorization of out-group faces and more accurate memory for in-group faces. Whereas these accounts further emphasize attentional and motivational factors, alternative expertise-based accounts suggest long-term perceptual learning as the basis of these effects. This project tested predictions of these competing accounts for the perceptual and attentional basis of face categorization (strand 1), and for the effect of category information on recognition memory (strand 3). We were further interested in examining the neural basis of facial age and ethnicity representations (strand 2). Strand 1 examined perceptual and attentional processes during face categorization. Overall, the results do not support socio-cognitive theories of in- versus out-group categorization. First, a hypothesized “age-feature theory”, assuming categorization of older faces via the detection of wrinkled skin as an out-group defining feature, was not supported by study 1. Second, in study 3 we did not detect evidence for an enhanced allocation of attentional resources to own-age faces. Third, study 2 revealed evidence for more efficient holistic processing for own-age faces in young adults. As holistic processing is typically assumed to require perceptual expertise with a certain stimulus class, this finding is well in line with an expertise-based explanation of more efficient processing of owngroup faces. Strand 2 was concerned with the neural representation of face category information. In a series of priming experiments, we observed that the successive presentation of two age-congruent faces resulted in less negative ERPs at occipito-temporal channels, approximately 250-400 ms after the presentation of the second face. This category repetition effect was independent of matching sex information between prime and target (study 5a), and did not reflect processes of response preparation (study 5b). Interestingly, both young and older participants (study 5c) demonstrated stronger ERP category repetition effects for older relative to young adult faces, suggesting more pronounced categorical processing of old and more individual processing of young faces. In two further experiments (study 6), we extended this paradigm to the study of ethnicity categorization and found ERP category repetition effects highly similar to those for age categorization. This finding suggests that category repetition effects are not driven by specific aspects of older or young faces, but reflect a more general aspect of processing category information from faces. In Strand 3, the influence of facial category information on recognition memory was examined. Study 7 provided the first evidence for the neural basis of an own-gender bias, the finding of more accurate memory for faces of one’s own gender. Moreover, neural correlates of the mere categorization memory bias were tested in study 8. We found no systematic evidence for early categorization of faces into social in- versus out-groups as the mechanism underlying these effects. At the same time, the own-race bias was accompanied by differential processing of own- and other-race faces at an early perceptual processing stage (study A3). Thus, while memory effects that do not depend on differential expertise with in- and out-group faces seem to exist (own-gender bias, mere categorization effects), ERPs suggest that different neural processes underlie these memory phenomena. In two further studies on the own-age bias, we found that more accurate memory for ownage faces does not depend on attentional load (study 10) or the distinctiveness of young and old faces (study 9). While the first of these findings clearly contradicts a socio-cognitive explanation of the own-age bias, the latter is well in line with an expertise-based explanation of the effect. Overall, the majority of the present results are not easy to integrate with recent socio-cognitive explanations for categorization advantages of out-group and memory advantages for in-group faces, and instead are more easily reconciled within an expertise-based framework. In particular, we found no evidence for categorization based on the detection of an “out-group defining feature” or for enhanced attentional resource allocation to in-group faces. Moreover, although ERP category repetition effects were stronger for old faces, this finding was similarly observed in young and old participants. Finally, while face memory biases that cannot be explained by enhanced expertise to ingroup faces seem to exist, such effects have a different neural basis as the own-race and own-age biases, and are therefore based on different underlying mechanisms. While future research will need to continue disentangling the precise cognitive and neural processes underlying each of these phenomena, the studies of the present project present an important first step in this direction.

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