Synchrony effects in cognition: the costs and a benefit.

The present study investigated whether younger and older adults' ability to inhibit distractors in a problem-solving task is affected by synchrony, or the match between circadian arousal periods and time of testing. Consistent with an inhibitory-deficit explanation of synchrony effects, both age groups showed heightened susceptibility to distraction at off-peak relative to peak times. In most instances, increased sensitivity to distraction disrupted problem-solving performance; however, when distracting material was related to task goals, individuals actually benefited from reduced inhibitory efficiency. The present data are also consistent with other research in showing that access to and production of well-learned or familiar responses are not vulnerable to synchrony effects.