Distinct abilities associated with matching same identity faces versus discriminating different faces: Evidence from individual differences in prosopagnosics and controls.

Previous face matching studies provide evidence that matching same identity faces (match trials) and discriminating different face identities (non-match trials) rely on distinct processes. For example, instructional studies geared towards improving face matching in applied settings have often found selective improvements in match or non-match trials only. In addition, a small study found that developmental prosopagnosics (DPs) have specific deficits in making match but not non-match judgements. In the current study, we sought to replicate this finding in DPs and examine how individual differences across DPs and controls in match versus non-match performance relate to featural versus holistic processing abilities. In all, 43 DPs and 27 controls matched face images shown from similar front views or with varied lighting or viewpoint. Participants also performed tasks measuring featural (eyes/mouth) and holistic processing (part-whole task). We found that DPs showed worse overall matching performance than controls and that their relative match versus non-match deficit depended on image variation condition, indicating that DPs do not consistently show match- or non-match-specific deficits. When examining the association between holistic and featural processing abilities and match versus non-match trials in the entire group of DPs and controls, we found a very clear dissociation: Match trials significantly correlated with eye processing ability ( r  = .48) but not holistic processing ( r  = .11), whereas non-match trials significantly correlated with holistic processing ( r  = .32) but not eye processing ability ( r  = .03). This suggests that matching same identity faces relies more on eye processing while discriminating different faces relies more on holistic processing.