The effect of feedback on face matching accuracy

In face matching, observers have to decide if two photographs depict the same person or different people. This is a remarkably difficult task so the current study investigated whether it can be improved when observers receive feedback for their performance. In five experiments, observers’ initial matching performance was recorded before feedback for their accuracy was administered across three blocks. Improvements were then assessed with faces that had been seen previously with or without feedback and with completely new, previously unseen faces. In all experiments, feedback failed to improve face-matching accuracy. However, trial-by-trial feedback helped to maintain accuracy at baseline level after feedback was withdrawn again, even with new faces (Experiments 1 to 3). By contrast, when no feedback was given throughout the experiment (Experiments 1 to 3) or when outcome feedback was administered at the end of blocks (Experiments 4 and 5), a continuous decline in matching accuracy was found, whereby observers found it increasingly difficult to tell different facial identities apart. A sixth experiment showed that this decline in accuracy continues throughout when the matching task is prolonged substantially. Together, these findings indicate that observers find it increasingly difficult to differentiate faces in matching tasks over time, but trial-by-trial feedback can help to maintain accuracy. The theoretical and practical implications of these findings are discussed.