A registered report testing the effect of sleep on Deese-Roediger-McDermott false memory: greater lure and veridical recall but fewer intrusions after sleep

Involvement of episodic memory in language comprehension: Naturalistic comprehension pushes unrelated words closer in semantic space for at least 12 h

Recent experience with a word significantly influences its subsequent interpretation. For instance, encountering bank in a river-related context biases future interpretations toward 'side of a river' (vs. 'financial bank'). To explain this effect, the episodic context account posits that episodic memory helps bind word meanings in the language input, creating a temporary, context-specific representation that can bias subsequent lexical interpretation. This account predicts that even unrelated words would be linked together in episodic memory, potentially altering their interpretation. In Experiments 1-3, participants read unrelated word pairs (e.g., sword-microwave, privacy-export) embedded in meaningful sentences, then completed a speeded relatedness judgement task after delays of 5 min, 20 min, or 12 h (including sleep). Results showed that sentence exposure increased the likelihood of the unrelated pairs being judged as related-a robust effect observed across all delay intervals. Experiment 4 showed that this exposure effect was abolished when words in a target pair were read in separate sentences, suggesting that the exposure effect may be dependent on lexical co-occurrence. Experiment 5, also with a 12-h delay (including sleep), additionally used an innovative word arrangement task to assess word relatedness without presenting the target pairs simultaneously or successively. In line with relatedness judgement, sentence exposure pushed the unrelated words closer in semantic space. Overall, our findings suggest that a context-specific representation, supported by episodic memory, is generated during language comprehension, and in turn, these representations can influence lexical interpretation for at least 12 h and across different linguistic circumstances. We argue that these representations endow the mental lexicon with the efficiency to deal with word burstiness and the dynamic nature of language.

Sleep and False Memory Production: The Modulating Role of Immediate Testing and Type of Retrieval

Data on the effect of sleep on false memories are mixed. Here we address two methodological issues which could explain these inconsistencies: the use of free recall vs. recognition tasks and the absence of immediate testing. In a mixed design, 8 word lists from the Deese-Roediger-McDermott task were administered to a Recall (n = 20) and a Recognition Group (n = 20) at 9 AM ('Wake' condition) or 9 PM ('Sleep' condition). Immediate Testing (IT) followed the presentation of 4 out of 8 lists. Delayed Testing was performed 12 h later. A week later, participants underwent the other condition with 8 different lists. In both groups: IT performance was similar between conditions; veridical recalls were facilitated by Sleep and by IT irrespectively of condition. False memories were enhanced in Sleep vs. Wake for non-tested lists only in the Recall Group. IT affected delayed false recognition regardless of the condition, whereas its effects on delayed recall differed between conditions: in Sleep, the false recall rate was similar between tested and non-tested lists, whereas in Wake, it was higher for tested than non-tested lists. Our results confirm that sleep enhances false recalls but not false recognitions when memory is tested directly after the retention interval. Moreover, immediate testing enhances veridical memory independently of condition, whereas its effect on false recall depends on the behavioural state in which retention occurs. Therefore, immediate testing could be usefully introduced in standard sleep-memory studies, while its use should be carefully evaluated in studies on sleep and false memories.

Learning new words via reading: The influence of emotional narrative context on learning novel adjectives

People learn new words in narrative contexts, but little is known about how the emotional valence of the narrative influences word learning. In a pre-registered experiment, 76 English-speaking adults read 30 novel adjectives embedded in 60 short narratives (20 positive, 20 negative, and 20 neutral valence). Both immediately after and 24 hr later, participants completed a series of post-tests, including speeded recognition, sentence completion, meaning generation, and valence judgement. Results showed that participants learned both the novel word form and its meaning. Compared with novel words experienced in the neutral contexts, those read in the emotional contexts (both positive and negative) showed better learning of orthographic form in the immediate post-test, but only those read in the negative context were recognised with greater accuracy in the delayed post-test. Furthermore, the valence of the context was reflected in the word meanings participants generated for each novel word, suggesting that word valence can be inferred from the valence of the contexts. Results from sentence completion and valence judgement were mixed, depending on the task demands. These findings are discussed with reference to theories of affective embodiment and the implications for learning abstract words are considered.

A systematic and meta-analytic review of the impact of sleep restriction on memory formation

Modern life causes a quarter of adults and half of teenagers to sleep for less than is recommended (Kocevska et al., 2021). Given well-documented benefits of sleep on memory, we must understand the cognitive costs of short sleep. We analysed 125 sleep restriction effect sizes from 39 reports involving 1234 participants. Restricting sleep (3-6.5 hours) compared to normal sleep (7-11 hours) negatively affects memory formation with a small effect size (Hedges' g = 0.29, 95 % CI = [0.13, 0.44]). We detected no evidence for publication bias. When sleep restriction effect sizes were compared with 185 sleep deprivation effect sizes (Newbury et al., 2021) no statistically significant difference was found, suggesting that missing some sleep has similar consequences for memory as not sleeping at all. When the analysis was restricted to post-encoding, rather than pre-encoding, sleep loss, sleep deprivation was associated with larger memory impairment than restriction. Our findings are best accounted for by the sequential hypothesis which emphasises complementary roles of slow-wave sleep and REM sleep for memory.