Skill Memory Escaping from Distraction by Sleep— Evidence from Dual-Task Performance

Background: Sleep facilitates off-line consolidation of memories, as shown for learning of motor skills in the absence of concomitant distractors. We often perform complex tasks focusing our attention mostly on one single part of them. However, we are equally able to skillfully perform other concurrent tasks. One may even improve performance on disregarded parts of complex tasks, which were learned implicitly. In the present study we investigated the role of sleep in the off-line consolidation of procedural skills when attention is diverted from the procedural task because of interference from a concurrent task. Methodology/Principal Findings: We used a dual-task paradigm containing (i) procedural serial reaction time task (SRTT), which was labeled as subordinate and unimportant and (ii) declarative word-pair association task (WPAT), performed concomitantly. The WPAT served as a masked distractor to SRTT and was strongly reinforced by the instructions. One experimental and three control groups were tested. The experimental group was re-tested after two nights of sleep (sleep group, SG). The first control group had sleep deprivation on the first post-learning night (nighttime-awake group, NA), the second control group was tested in the morning and then re-tested after 12-hours (daytime-awake group, DA); the third one had the same assignments as DA but with a subsequent, instead of a concomitant, WPAT (daytime-awake-subsequent-WPA