Effect of circadian rhythms on retrieval-induced forgetting.

This study investigated the effects of natural circadian rhythms on retrieval-induced forgetting (RIF; Anderson et al. in J Exp Psychol Learn Mem Cogn 20:1063-1087, 1994). Individuals tested at optimal times (i.e., morning persons tested in the morning and evening persons tested in the evening) showed a significantly greater RIF effect than individuals tested at non-optimal times (i.e., morning persons tested in the evening and evening persons tested in the morning). Thus, the limited quantity of resources available to allocate in the inhibitory activity during non-optimal times produced a significant decrement in RIF. These findings are compatible with the inhibitory account of RIF and with the notion of a resource-demanding process underlying this memory phenomenon.