Is learning facts via audio while sleeping possible?

Question

Is there a way to make onself remember facts from an audiobook (containing for instance a list of countries and their capitals) played out loud while sleeping?

Answer 1

Theoretical perspective: No. I don't think so. From a cognitive information processing perspective, I would hypothesise that declarative learning of new facts would not occur while sleeping. Of course, learning declarative facts while awake, but in bed (e.g., when going to sleep or when waking up in the morning) is possible, and sleep is important in consolidating what is learnt during the day. I don't think the mind is capable of the kinds of information processing required to process facts when asleep.

Empirical perspective: Nonetheless, my theoretical perspective above may be wrong, so it is worth while looking at the empirical evidence. I found an early review of research in Simon and Emmons (1955). The study critically evaluates 10 or so studies on sleep learning and suggests that each of them suffers from some form of methodological weakness.

Wood et al (1992) provide a more recent summary of the literature:

When a distinguished committee of the National Research Council (NRC) recently concluded that sleep learning deserves a "second look" from experimenters (Druckman & Swets, 1988; Swets & Bjork, 1990). a distinguished sleep researcher swiftly and pungently disagreed (Webb, 1990). This controversy is not new to the field of sleep learning. Disagreement has been common since the mid-1950s, when Simon and Emmons (1955. 1956) severely criticized the methodology of existing studies and demonstrated that recall and recognition for verbal material presented during sleep do not occur when proper experimental controls are exercised.

Although the views of Simon and Emmons were generally accepted, in ensuing years some empirical studies continued to report evidence of learning for verba! information presented during sleep (see reviews by Aarons. 1976; Eich, 1990; Hoskovec, 1966). Though subject to methodological criticism, their findings were buttressed by evidence from electroencephalographic and evoked potential studies that (a) transmission of auditory information to the primary auditory cortex is not different during sleep and the waking state, (b) habituation and conditioning can occur during sleep in both nonhuman animals and humans, and (c) some transfer of information to long-term memory occurs during sleep (see review by Wood, 1990). Furthermore, recent studies have suggested the existence of a cognitive unconscious (Kihistrom. 1987) and indicated that information processed outside of conscious awareness, for example, while under anesthesia (Kihistrom, Schacter, Cork, Hurt, & Behr, 1990), can be stored in memory and exert an influence on later performance. In addition, research with both amnesic and normal subjects has demonstrated the existence of implicit memory, that is, learning that does not require deliberate or conscious recollection of experience (see reviews by Richardson-Klavehn & Bjork. 1988, and Schacter, 1987).

Specifically, it appears that in their study Wood et al (1992) did not find any effect:

This study examined implicit memory for words presented during sleep. Ten experimental subjects were presented with word pairs including a homophone and a close associate (e.g., “tortoise-hare”) and with category-instance pairs (e.g., “bird-cardinal”) during REM or Stage 2 sleep and tested immediately afterward. Twelve control subjects underwent the same procedure while awake. Unlike the controls, subjects in the sleeping condition showed no learning effects on the implicit memory tasks. Recall and recognition were observed in a few cases, but only when presentation was immediately followed by arousal.

References

• Simon, C. W., & Emmons, W. H. (1955). LEARNING DURING SI. EEP?. LEARNING, 52(4), 1055. PDF
• Wood, J. M., Bootzin, R. R., Kihlstrom, J. F., & Schacter, D. L. (1992). Implicit and explicit memory for verbal information presented during sleep. Psychological Science, 3(4), 236-239.