Abstract
The present study assessed the effects of awareness at encoding on off-line learning during sleep. A new framework is suggested according to which two aspects of awareness are distinguished: awareness of task information, and awareness of task processing. The number reduction task (NRT) was employed because it has two levels of organization, an overt one based on explicit knowledge of task instructions, and a covert one based on hidden abstract regularities of task structure (implicit knowledge). Each level can be processed consciously (explicitly) or non-consciously (implicitly). Different performance parameters were defined to evaluate changes between two sessions for each of the four conditions of awareness arising from whether explicit or implicit task information was processed explicitly or implicitly. In two groups of subjects, the interval between the pre-sleep and post-sleep sessions was filled either with early-night sleep, rich in slow wave sleep (SWS), or late-night sleep, rich in rapid eye movement (REM) sleep. Results show that implicit processing of explicit information was improved in the post-sleep relative to the pre-sleep session only in the early-night group. Independently of sleep stage, changes between sessions occurred for explicit processing of implicit information only in those subjects who gained insight into the task regularity after sleep. It is concluded that SWS but not REM sleep specifically supports gains in computational skills for the processing of information that was accessible by consciousness before sleep.
Highlights
There is increasing evidence that sleep supports memory consolidation (Karni et al, 1994; Maquet, 2001; Walker et al, 2002; Walker and Stickgold, 2004; Born et al, 2006)
The meaning of this transfer to take place during sleep is that if identical neocortical networks are engaged in encoding, storage and retrieval of information (Damasio, 1989; Khader et al, 2005), these networks are deprived from afferent inputs during sleep so that no interference would occur between memories being consolidated and external information being continuously processed during wake (McClelland et al, 1995; Kali and Dayan, 2004)
The two groups did not differ in the proportions of other sleep stages (p > 0.2)
Summary
There is increasing evidence that sleep supports memory consolidation (Karni et al, 1994; Maquet, 2001; Walker et al, 2002; Walker and Stickgold, 2004; Born et al, 2006). Parameters were subjected to repeated-measures ANOVA with two between-subjects factors, Sleep Group (Early-NG vs Late-NG) and Performance Group (Solvers vs Non-solvers), and two within-subjects variables, Session (pre-sleep vs post-sleep) and Response (R, depending on the specific type of knowledge tested, difference-rule related vs identity-rule related; unpredictable vs predictable, or R1 to R7).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have