Table 1.
Review of the experiments which investigated the link between learning-related dream reports and memory performance.
| Ref | Memory | Task | Nt | nLRD | Scoring | Dreams collection | Statistical paradigm | Res |
|---|---|---|---|---|---|---|---|---|
| (Fiss et al.18) | Explicit verbal | Story recall | 6 | ? | Content checklist procedure | 1 night in the lab with REM awakening | Correlation between inc of the story into dreams and memory performance | YES |
| (De Koninck et al.19) | Explicit verbal | French language learning | 8 | ? | External-scoring: detection of French | Dream journal from pre-course to post-course | Correlation between learning efficiency and latency to first French inc into dreams | YES |
| (Wamsley et al.26) | Explicit visuo-spatial | virtual maze navigation task | 50 | 4,8% | Self-scoring & experimenter validation | Awakenings in N1 and at the end of the nap | Group comparison | YES |
| (Schoch et al.21) | Explicit visuo-verbal | Word-picture association | 22 | ? | External-scoring by 2 blind raters of congruent vs incongruent inc | 1 night in the lab with multiple awakenings (REM & NREM) | Correlation between inc score and overnight memory retention |
YES in NREM NO in REM |
| (Wamsley & Stickgold27) | Explicit visuo-spatial | virtual maze navigation task | 17 | 8,47% | External-scoring by blind raters of direct explicit inc* of the maze | 1 night in the lab with multiple awakenings in N1, 1 in N2 and 1 in N2 or REM sleep |
- Group comparison (those with at least one direct inc vs those with no direct inc of the task into dreams) - ANCOVA |
YES NO |
| (De Koninck et al.22) | Explicit visuo-spatial | Vertical inversion of the visual field with goggles | 8 | 4,50% | External-scoring: incorporations of visual inversions | 2 night in the laboratory with REM awakening | Better score on 2/3 of the tests of adaptation to the visual inversion for the participants with inc of the task into dreams (tendency) | ? |
| (Cipolli et al.20) | Explicit verbal | Meaningless sentences (3 × 19 words) | 12 | 12,100% | External scoring by 2 blind raters looking for loose associations with the stimuli in dreams resulting in 31/35 dream reports with inc of the task | Several awakenings in the lab after 5 min of REM sleep | ANOVA testing the retention rate for content words as a function of inc into dream reports + moment of recall + REM period | NO |
| (Pantoja et al.23) | Perceptuo-motor-spatial-emotional & higher level cognition | Computer game « Doom » | 22 | 17,77% | Not specified | 2 nights in the laboratory with REM awakenings in the 2nd night | Correlation between the amount of game-related elements into dreams and performance gains (inverted U function) | NO |
| (Schredl & Erlacher25) | Procedural & visuo-spatial | Mirror tracing | 20 | 1,5% | External-scoring: laboratory experiment and mirror tracing task references (binary score). | 2 nights in the lab with REM awakenings in the second night (from the 2nd REM period) | Correlation between reference to 1) the experiment, 2) the laboratory, and 3) the task into dreams and performance to the task | NO |
| (Stamm et al.29) | Explicit visuo-spatial | virtual maze navigation task | 65 | 24,37% | External-scoring by blind raters of direct and indirect inc of the maze | 1 night in the lab with multiple awakenings in N1, 1 in N2 and 1 in N2 or REM sleep |
Group comparison (those with inc vs those with no inc of the task into dreams) |
NO |
| (Wamsley et al.28) | Explicit visuo-spatial & procedural motor | virtual maze navigation task & motor sequence typing task | 51 | 6,12% | External-scoring by blind raters of direct and indirect inc of the maze | 1 night in the lab with multiple awakenings in N1, 1 in N2 and 1 in N2 or REM sleep |
Group comparison (those with inc vs those with no inc of the task into dreams) |
NO |
| (Nefjodov et al.24) | Procedural & visuo-spatial | Computer coordination and balance motor task | 13 | ≥7,≥53% | Self- & external-scoring | 1 night in the laboratory with REM awakenings (from the 2nd REM period) | Correlation between reference to balance-related elements into dreams and task performance | NO |
Ref, references; Memory, type of memory targeted by the task; Task, task performed before sleeping and which presence in dreams was scored; Nt, total number of participants; nLRD, number and percentage of participants with learning-related dreams; Scoring, method for scoring whether dreams were learning-related or not; Dream collection, method used to collect dreams; Statistical paradigm, method used to test whether dreaming of the learning phase was associated with improved memory performance; Res, results i.e. response to the question “Did the results show that the more the dreams are learning-related or the more learning-related dreams, the better the performance after sleep?”; ?, unknown; inc, incorporation; N1, sleep stage N1; N2, sleep stage N2; * indirect incorporations excluded because not related to performance.