New research suggests that 24-month-olds have a superior ability to recall things they observed on a screen compared to 15-month-olds, particularly if they slept within four hours after the learning session. The duration of sleep during this period directly correlated with how well they remembered the content. The paper was published in the Journal of Sleep Research.
Research suggests that sleep plays a crucial role in memory consolidation, the process by which short-term memories are transformed into long-term memories. During sleep, particularly in the slow-wave and REM (rapid eye movement) stages, the brain reorganizes and strengthens neural connections, making memories more stable and durable. This consolidation process helps to integrate new information with existing knowledge, enhancing learning and retention. Consequently, adequate sleep is essential for optimal memory function, and sleep deprivation can impair memory consolidation and overall cognitive performance.
Scientists have proposed several theories explaining the neurobiology of this mechanism, but the superior theory remains unidentified. The effects of sleep on memory in infants, in particular, are still uncertain, with a recent study on the topic producing inconclusive or counterintuitive results.
In their new study, Neele Hermesch and her colleagues wanted to examine whether caregivers’ help and guidance during viewing of televised contents facilitates the effects of sleep on memory consolidation in 15 and 24-month-old infants. They conducted a study using the deferred imitation paradigm, a method to assess an infant’s ability to observe an action and replicate it later, as a measure of memory.
The study included 51 infants at 15 months and 54 at 24 months, with girls making up about 45% of the participants. The infants were divided into three groups: one that would nap post-learning, another that wouldn’t nap, and a control group. Infants in the nap group were required to sleep for at least 30 minutes within four hours following the learning session. The study was conducted remotely.
Prior to the study, the researchers provided participants with an actiwatch (a motion-detecting wrist device used to monitor sleep), a tablet for displaying video demonstrations, materials for the test session, and a small participation gift. Two video chat sessions with infants and their caregivers were scheduled 24 hours apart.
During the experimental session, caregivers showed their infants the study material on the provided tablet. A female model demonstrated three distinct actions on various objects in succession in these videos. Caregivers were instructed to draw the infants’ attention to the screen with comments but were told not to verbally identify the objects or actions. For other videos, they remained silent. Following these demonstrations, one group of children napped within four hours, while another did not.
Twenty-four hours later, another meeting took place where caregivers presented the previously demonstrated objects to the infants, and researchers observed the infants’ ability to accurately reproduce the actions. The control group only wore the actiwatch without viewing the demonstrations, but they were given the objects during the test session. This setup allowed the researchers to differentiate learned behaviors from spontaneous interactions with the objects.
The findings revealed that 24-month-olds exhibited a higher capability than 15-month-olds in recalling and imitating the demonstrated actions. While 15-month-olds generally struggled to imitate, 24-month-olds were able to remember the actions irrespective of having napped. Yet, those who did nap showed more accuracy than their peers who did not nap.
The presence of caregiver commentary during the video did not affect the imitation levels. Additionally, the amount of daily screen time as reported by parents did not correlate with the infants’ ability to replicate the actions. Nonetheless, the longer the 24-month-olds slept within the four-hour window post-demonstration, the better they were at imitating the target actions.
“The present study demonstrates that sleep may also help infants with the challenge of remembering information from screens. From a theoretical perspective these findings shed further light on how screen content is processed in the developing brain. Given the increasing role screen media plays in infants’ everyday life, it is necessary to increase our understanding of the complex relationships between sleep, memory, and media to provide evidence-based guidance to parents and practitioners,” the study authors concluded.
The study sheds light on the effects of sleep on memory consolidation in infants. However, it should be noted that infants watched activities that might have not been of particular interest to them. Caregiver’s guidance during the demonstrations was also very basic. Results in situations where infants remember activities more important to them and with more elaborate adult guidance might not yield equal results.
The paper, “Sleep-dependent memory consolidation of televised content in infants,” was authored by Neele Hermesch, Carolin Konrad, Rachel Barr, Jane S. Herbert, and Sabine Seehagen.