Circadian Rhythm and Memory Performance: No Time-Of-Day Effect on Face Recognition

The circadian rhythm regulates arousal and activity levels throughout the day and determines hours of optimal cognitive performance. Thus far, circadian fluctuations in face recognition performance received little attention in the research literature. The current experiment investigated the effects of time-of-day optimality on the ability to recognize faces and discriminate between the contexts in which where they were encountered. Morning- and evening-type participants (N = 91) encoded faces in a crime-related and a neutral context, either at their optimal or non-optimal time of day. Contrary to our hypotheses, neither face recognition nor source monitoring performance benefited from testing at optimal time of day. We discuss peculiarities of face processing that could account for the discrepancy of our findings with word recall and recognition literature.