Figure 2.

Memory performance across a nap. A, B, Memory change scores were computed as the difference in recall error between the two tests. In general, individuals placed objects less accurately at Test 2 than at Test 1. This decline was worse for low-value objects (in red) compared with high-value objects (in blue) in Experiment I but not in Experiment II. Error bars depict SEM after correcting for across-subject variability, such that these measures of variability correspond to the error term for the within-subjects contrast as a function of value. C, D, In Experiment II but not in Experiment I, memory accuracy for low-value objects was correlated with delta power at frontopolar midline scalp locations during slow-wave sleep. *Indicates significant difference between conditions.