Targeted memory reactivation (TMR) is a methodology employed to manipulate memory processing during sleep. TMR studies have great potential to advance understanding of sleep-based memory consolidation and corresponding neural mechanisms. Research making use of TMR has developed rapidly, with over 70 articles published in the last decade, yet no quantitative analysis exists to evaluate the overall effects. Here we present the first meta-analysis of sleep TMR, compiled from 91 experiments with 212 effect sizes (N ϭ 2,004). Based on multilevel modeling, overall sleep TMR was highly effective (Hedges' g ϭ 0.29, 95% CI [0.21, 0.38]), with a significant effect for two stages of non-rapid-eyemovement (NREM) sleep (Stage NREM 2: Hedges' g ϭ 0.32, 95% CI [0.04, 0.60]; and slow-wave sleep: Hedges' g ϭ 0.27, 95% CI [0.20, 0.35]). In contrast, TMR was not effective during REM sleep nor during wakefulness in the present analyses. Several analysis strategies were used to address the potential relevance of publication bias. Additional analyses showed that TMR improved memory across multiple domains, including declarative memory and skill acquisition. Given that TMR can reinforce many types of memory, it could be useful for various educational and clinical applications. Overall, the present meta-analysis provides substantial support for the notion that TMR can influence memory storage during NREM sleep, and that this method can be useful for understanding neurocognitive mechanisms of memory consolidation. Public Significance StatementSensory cues can be used to reactivate associated memories during sleep and thus promote memory consolidation. This meta-analysis shows that targeted memory reactivation during sleep can improve memory performance with a small to moderate effect, and that this effect is most clearly evident when memories are reactivated during Stages 2 and 3 of non-rapid-eye-movement (NREM) sleep.

, J-C. (in press). Do you get us? A multi-experiment, meta-analytic test of the effect of felt understanding in intergroup relations.

The study of affectionate touch centers on gentle stroking. Yet friendly physical contact entails other actions, such as embracing, holding, kissing, leaning, petting, squeezing, or tickling. Here, we probed whether these actions are redundant or can be meaningfully differentiated by asking participants (N = 161) to complete a few tasks for each action. Coloring of body maps emphasized touching of upper body hairy and glabrous skin, contrary to the notion that only the former is relevant in affectionate touch. A linear discriminant analysis categorized colorings with 91% accuracy, showing that each touch action has a unique somatosensory topography. Automated text analysis of open-ended situational descriptions revealed touch-specific affective contexts that concerned one's own or the other's feelings and could be both positive and negative. Last, the touch actions differed in their self-reported comfort and frequency as a function of the closeness of interaction partners. Thus, rather than being redundant, affectionate touch actions are highly differentiated in terms of their somatosensory and socioaffective processes. Moreover, their differential patterns suggest that they each play a unique regulatory role for the toucher, the touchee, and their relationship.

The idea that external rhythms synchronize attention cross-modally has attracted much interest and scientific inquiry. Yet, whether associated attentional modulations are indeed rhythmical in that they spring from and map onto an underlying meter has not been clearly established. Here we tested this idea while addressing the shortcomings of previous work associated with confounding (i) metricality and regularity, (ii) rhythmic and temporal expectations, or (iii) global and local temporal effects. We designed sound sequences that varied orthogonally (high/low) in metricality and regularity and presented them as task-irrelevant auditory background in four separate blocks. The participants’ task was to detect rare visual targets occurring at a silent metrically aligned or misaligned temporal position. We found that target timing was irrelevant for reaction times and visual event-related potentials. High background regularity and to a lesser extent metricality facilitated target processing across metrically aligned and misaligned positions. Additionally, high regularity modulated auditory background frequencies in the EEG recorded over occipital cortex. We conclude that external rhythms, rather than synchronizing attention crossmodally, confer general, non-temporal benefits. Their predictability conserves processing resources that then benefit stimulus representations in other modalities.

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