The effect of post-encoding sleep on infant memory performance in a deferred imitation task with live and video demonstrations
Creators: name: Hermesch, Neele
name: Konrad, Carolin
name: Barr, Rachel
name: Herbert, Jane
name: Seehagen, Sabine
Publisher: name: Open Science Framework
Year: 2022
Subjects: subject: Developmental Psychology
subject: Social and Behavioral Sciences
subject: Psychology
subject: FOS: Psychology
subject: deferred imitation
subject: infant
subject: memory
subject: sleep

description: In adults, sleep plays a crucial role in several memory processes (Diekelmann &amp; Born, 2010; Klinzing et al., 2019). Sleeping soon after encoding new memories may help to strengthen these memories, a process referred to as sleep-dependent memory consolidation. There is growing evidence that post-encoding sleep enhances memory performance also in infants and young children, for example in a visual recognition task at 3 months of age (Horváth et al., 2017), in a deferred imitation paradigm with infants aged 6 and 12 months (Seehagen et al., 2015), in a word-learning task with 16-month-old infants (Horváth et al., 2015) and in an object-location task with pre-schoolers aged 36-67 months (Kurdziel et al., 2013). Given enormous developmental changes in both infant sleep (Galland et al., 2012) and memory (Hayne &amp; Herbert, 2020) throughout the first years of life, potential task-specific effects, and several failures to replicate sleep-mediated memory effects in adults (for overview: Cordi &amp; Rasch, 2021), further replications with different tasks and across different age groups are indispensable to understand how sleep may benefit memory in infancy. Therefore, the first objective of this study is to replicate the beneficial effect of a post-encoding nap on memory in 15- and 24-month-old infants using a deferred imitation paradigm (RQ1). We will use a comparable design as in Seehagen et al. (2015, Exp. 2): Infants will be randomly assigned to a nap condition (≥ 30 min of naturally occurring nap within 4 hours after an experimenter demonstrated the target actions) or a no nap condition (0 min of sleep within 4 hours after an experimenter demonstrated the target actions). Reproduction of target actions will be tested after a 24-hour delay to allow for a recovery sleep in all infants (Seehagen, 2019, 2022). To infer memory of the target actions the number of reproduced target actions of infants in the experimental conditions will be compared to number of target actions spontaneously produced by infants in a baseline condition who did not see any demonstrations of the target actions Data for the baseline condition was collected as part of another experiment (see below). With this experiment we will also address a second research question. Stickgold &amp; Walker (2013) proposed that sleep-dependent memory consolidation might be a selective process favouring memories tagged as “relevant”. Preliminary evidence exists for selective sleep-dependent memory benefits in infants (Konrad et al., 2019). It is not yet understood which memories could receive relevance tags in infants as cues of relevance may differ from those in adults. One “relevance cue” could be the presentation mode of a potential learning experience. Infants show greater difficulties learning and remembering televised as compared to live content (Strouse &amp; Samson, 2021). Among other explanations, this so-called transfer deficit is attributed to infants’ inability to perceive media content as relevant as it typically lacks contingent social reactions known from in-person interactions (Troseth et al., 2006). Therefore, comparing sleep-dependent memory consolidation of televised vs. live content can help address the question of whether post-encoding sleep benefits memory regardless of the presentation mode of the learning. The second objective of this experiment addresses this question (RQ2). If televised content is perceived as irrelevant, it should be less likely to undergo sleep-dependent memory consolidation and a potential memory benefit of post-encoding sleep should be less pronounced. To address this question, we will compare data from the present experiment, in which infants see a live demonstration of target actions to data from a recently completed experiment (preregistered: https://osf.io/nehf5) in which infants see a video demonstration of target actions (= video experiment). Briefly summarised, in the video experiment we compare sleep-dependent memory consolidation of televised content with and without caregiver scaffolding. Infants watch two demonstration videos: one video is accompanied by caregiver scaffolding (a standardised and empty verbal description of the demonstrated target actions), one video is not scaffolded. As described above, half of the infants are assigned to a nap and a no nap condition. Reproduction of target actions is assessed 24 hours later. In an additional baseline condition, spontaneous production of target actions is assessed. To allow cross-experiment comparisons, and thereby to answer RQ2, we will use the exact same procedures in the planned live experiment as in our ongoing video experiment including the within-subject manipulation of caregiver scaffolding. Due to the analogue design, some sections of this preregistration are identical or refer to the preregistration of the video study mentioned above.