New research shows that birds babbling involves its own specialized brain circuitry, separate from that used for adult singing. This finding underscores the importance of the exploratory behaviors -- such as infant stepping, hand motions, vocalizations and play -- that help young animals learn how to use their bodies and make sense of the world.

According to the study, people expend more effort on actions when the message to move is accompanied by a little subliminal "pep talk." The researchers tested this idea by showing a group of exertion-related words such as "vigorous" to people and later measuring their performance on a handgrip test. People who saw encouraging words such as "good" mixed in with the exertion words had stronger and quicker grips that those who just saw exertion words, suggesting that the positive words motivated people to expend extra effort on the task.