How Physical Activity And Time of Day Influence Judgments of Learning and Free Recall
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Previous research suggests the existence of a time of day (TOD) effect in cognitive functioning such that people have an optimal time each day during which their cognitive functions peak: typically, older adults peak in the morning and younger adults peak in the evening (May, Hasher, & Stolzfus, 1993). Explicit memory is one cognitive function that has shown a TOD effect (e.g., Schmidt, Collette, Cajochen, & Peigneux, 2007). In addition, exercise has been shown to improve explicit memory (e.g., Labban & Etnier, 2011). Thus it may be possible to offset the decline in explicit memory that has been observed during non-peak times of the day. The main purposes of this study were to determine if the TOD influences metacognitive judgments, and to test if an acute bout of exercise would offset the TOD effect in a young adult, evening-type population. The study utilized a 2 (type of activity: exercise vs. sedentary) X 2 (TOD: morning vs. afternoon) repeated-measures design. A TOD effect (i.e., better performance in the afternoon than in the morning) emerged for memory and judgment of learning (JOL) magnitude. However, exercise did not offset the morning decrement in performance. These results suggest that young, evening-type adults have better recall in the afternoon and that they are aware of this TOD effect, as evidenced by the magnitude of their JOLs. Additional research is needed to determine if exercise or other interventions can offset this TOD effect.