Babies' Naps Bolster Learning

University of Arizona psychologists Rebecca Gomez, Richard Bootzin, and Lynn Nadel found that babies who got a little daytime shut-eye were more likely to exhibit an advanced level of learning, known as abstraction. As they describe in the August issue of Psychological Science, they played recordings of "phrases" from an artificial language to forty-eight 15-month-old infants during a learning session. For example, they repeatedly played phrases like "pel -- wadim -- jic" until the babies became familiar with them. These phrases contained three units, with the first and last unit forming a relationship. In this case, pel predicts jic. Even though these are nonsensical sounds, Gomez explains, the language shares some similarity with structure found in English sentences, such as the subject-verb agreement in "the companies there are merging."

Before Gomez and colleagues tested the infants' learning of this nonsensical language, some infants took normally scheduled naps. Others were scheduled at a time when they would not nap after learning. When the infants returned to the lab, they again heard the recordings-- along with novel phrases in which the predictive relationship between the first and last word was new. By carefully watching the babies' gazes as they listened to both old and novel phrases, Gomez was able to rate their level of attention. Longer looking at a flashing light (coinciding with the phrases) signaled attention, which indicated the babies had learned a particular phrase or relationship.

There were interesting differences between the infants who had napped and those who had not. The infants who did not sleep recognized the phrases they had learned earlier, but the babies who had slept in between generalized their knowledge of the predictive relationships to new phrases. Gomez interprets this as evidence that napping supports abstract learning--that is, the ability to detect a general pattern in new information.

This kind of abstract learning indicates a qualitative change in memory, Gomez explains: "Such a change plays an essential role in cognitive development by sustaining sensitivity to previously encountered information, while enabling learners to generalize to novel cases."