Napping Benefits Infants When They Learn a Challenging Task, but not an Easy One

• In Event: Poster Session 09
  In Poster Session: PS 09 Topic - Attention, Learning, Memory

Abstract

Sleep facilitates learning in infancy (Kurdziel, Duclos & Spencer, 2013). Experimental learning tasks are designed to be challenging—infants must consolidate new information or receive training on how to solve a novel problem. The outcome measure is how performance improves after a nap or night sleep. Research with adults shows that night sleep may only facilitate learning if the task is difficult (Sio, Monaghan, & Ormerod, 2013). Thus, we investigated whether sleep consolidates information similarly for infants by 1) comparing the performance of infants who found a novel motor problem difficult with those who found it easy and 2) teasing apart the impact of day and night sleep on learning by varying whether infants napped between training and test and scheduling a follow-up test after a night’s sleep.

64 new walkers (mean age=13.94 months; SD=2.01; 24 girls) who had just given up crawling participated in a locomotor problem-solving task over two days: training, same-day test (after a nap, delay with no nap, or immediately), and a next-day follow-up. At training, experimenters taught infants to solve the problem of crawling through a nylon tunnel. During the transition to walking, infants are reluctant to return to crawling, making this task uniquely challenging (Berger & Scher, 2017). Infants began standing at the tunnel opening and were encouraged to reach a caregiver at the other end. Training comprised a 3-phase, 15-step protocol, with each phase increasingly hinting towards solving the problem: 5 standing prompts at the tunnel entrance, 5 hands-and-knees prompts, and 5 times rolling a toy to demonstrate the path. The session ended once infants crawled through the tunnel. Coders documented how many training steps infants needed, how many postural shifts infants made inside the tunnel, and time spent in the tunnel. Infants were grouped according to the three delay conditions and whether they initially found the task easy (zero prompts, n=27) or difficult (≥1 prompt, n=37).

Shapiro-Wilk tests revealed departures from normality for all variables (p’s < .01). Kruskal-Wallis analyses of variance showed main effects for condition and expertise for shift change scores from training to test (H=13.20, p=.02) and for time in tunnel change scores from test to follow-up (H=11.56; p=.04).

We observed distinct trajectories over the three sessions reflecting an interaction between delay condition and whether infants initially found the tunnel task challenging. For postural shifts, easy group infants in the immediate condition displayed improvement most rapidly, likely due to little opportunity for memory decay. Among those with a delay, infants who napped showed the greatest improvement at test (Figure 1). For time spent in the tunnel, the combination of napping and night sleep was most effective for babies who found the problem difficult (Figure 2).

Frequent sleep—napping—may be necessary to compensate for infants’ limited hippocampal capacity, whereas REM sleep at night may promote the neural reorganization required for learning (Cao, Herman, West, Poe, & Savage, 2020). The difference in trajectories based on outcome variable suggests different roles for sleep depending on cognitive demands, such as inhibition or information processing.

Authors

• Aaron DeMasi, The Graduate Center, The City University of New York
  Presenting Author

• Melissa N. Horger, Graduate Center, City University of New York
  Non-Presenting Author

• Angelina Marie Allia, City University of New York College of Staten Island
  Non-Presenting Author

• Anat Scher, university of haifa
  Non-Presenting Author

• Sarah E. Berger, City University of New York College of Staten Island
  Non-Presenting Author