Humans act with purpose, but much is still unknown about how we become purposeful agents — that is, how we develop the ability to willfully make things happen. In a recent study to explore agency's mysterious roots, we tried to catch infants (婴儿) in the act of discovering their own agency, thereby revealing the process of agency formation.
Researchers place a baby into a cradle with a mobile suspended above. Then a scientist ties one end of a string to the mobile and the other to the infant's foot. Now if the baby moves, the toy will, too. By observing babies in this setup, scientists can watch as the infants learn and recall a simple cause-and-effect interaction: kick a foot and the mobile moves.
As predicted by the researchers, infants kicked significantly more when their foot was tethered (拴住) to the mobile than when it was not. However, when an experimenter pulled the string to make the mobile move instead, infants moved less than when the mobile was at rest. Furthermore, when we freed the babies' foot from the mobile, they kept on kicking at higher rate to make the toy respond — and were visibly frustrated when that did not happen.
Our observations also pointed to a notable pattern: The babies' initial movements consisted of twisting and pushing without clear direction. But once tethered to the mobile, the more intensely they moved, the more their attention was drawn to the effect their kicking had on it. At some point, the infants must have figured out that they had agency, thus the aimless movements became intentional action — a highly coordinated exchange between the tethered infant and the mobile.
The baby-mobile study emphasizes how understanding the relationship between an organism and its environment is essential to uncovering the origins of directed behavior. The experience of agency emerges only when an organism senses it is coupled to its environment. In this way of thinking, the interaction and relationship between the two are crucial for purpose to arise.
