Rebecca Gomez, Richard Bootzin, and Lynn Nadel in the psychology department at the University of Arizona in Tucson found that babies who are able to get in a little daytime nap are more likely to exhibit an advanced level of learning known as abstraction.
Nadel, a Regents’ Professor at the UA, described the group’s work (“Early Learning in Infants May Depend on Sleep”) in a session at the American Association for the Advancement of Science annual meeting in San Diego last month.
In their research, Nadel and his colleagues played recordings of "phrases" created from an artificial language to four dozen 15-month-old infants during a learning session. Their methodology included repeatedly playing 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 example, the first word, "pel," predicts the last, "jic." Even though these are nonsensical sounds, the language created for the test shares some similarity with structure commonly found in subject-verb agreement in English sentences.
Prior to being tested, some infants learning this faux language took their normally scheduled naps. Others were scheduled at a time when they would not nap following the session. When the infants returned to the lab, they again heard the recordings—along with a set of different phrases in which the predictive relationship between the first and last words was new.
By carefully watching the babies’ facial expressions as they listened to both old and new phrases, the researchers were able to rate their level of attention. They found that babies’ longer gazes at a flashing light that coincided with the phrases signaled attention, which indicated that they had learned a particular phrase or relationship.
Differences arose between the infants who had napped and those who had not. The infants who did not sleep after the sessions still recognized the phrases they had learned earlier. But those babies who had slept in between sessions were able to generalize their knowledge of sentence structure to draw predictive relationships to the new phrases. This suggests that napping supports abstract learning—that is, the ability to detect a general pattern contained in new information.