Figure 2.

Mean (± standard error of the mean) for cognitive performance tasks. (A) Psychomotor Vigilance Task-B Response Speed; (B) Digit-Symbol Substitution Task Number of Correct Responses. Higher values represent better performance. Left-side panels display data per condition across pre- and post-nap testing points. Marker shading in the left-side panels matches column shading in the right-side panels for each condition. To assist the reader in clearly identifying the post-nap slopes for each group, the bars on the right simply represent the slope of the mean points as displayed in the left panel.