A criterion-placement theory of face matching

Face matching is an important applied task that requires binary decisions to pairs of face images to determine whether these depict the same person (an identity match) or different people (a mismatch). While these choices are mutually exclusive, performance for match and mismatch trials appears to be dissociable, which poses a problem for theory development. The current study demonstrates that this dissociation arises from systematic response biases, which reflect individual differences in the placement of decision-making thresholds to distinguish matches from mismatches. When these biases are controlled or partialled out from classification accuracy, reliable associations between match and mismatch identifications are found. This is demonstrated over two experiments with a sample of over 500 participants, several face-matching tests, and a series of data simulations. These findings support a cognitive theory in which individual differences in the placement of decisionmaking thresholds provide the mechanism by which the identification of face matches and mismatches are linked.