Effects of Time of Day on Immediate Recall and Sustained Retrieval from Semantic Memory.

This study examined performance in tests of word recall recognition, and continuous retrieval from natural semantic categories in the morning and evening. Immediate recall was superior in the morning. The ability to sustain search of semantic memory (over 8 min per category) was superior in the evening. Results replicated and extended previous research, which suggests that time of day exerts differential effects on episodic and semantic memory, thus providing further evidence that these two memory systems are clearly distinct.