Thomas Andrew Gustafson
Understanding you exist as a person happens a lot sooner than you might think.
A study involving 40 cute, pudgy babies found that they were aware of their bodies — and even displayed a sense of ownership of them — less than two days after being born.
Both of those qualities are key ingredients in realizing your own existence, says the study's lead author, Maria Laura Filippetti, a doctoral candidate specializing in cognitive development at Birkbeck College, University of London.
"Body awareness refers to the feeling of being alive," she told Shots. "Body ownership refers to the feeling of having a body, the sense that this body belongs to me."
Past studies reveled how important these two aspects of human life were for infants, but this study was the first to discover it in newborns at birth.
How did the researchers figure it out? Filippetti and her colleagues tested the infants' ability to recognize themselves using a test similar to the old rubber hand illusion.
That test tricks the mind into thinking a fake rubber hand actually belongs to a person's body. Researchers lightly stroke a person's real hand with a paintbrush while it's hidden from his or her view. Simultaneously, the researchers stroke a rubber hand that's in plain sight. Stroking the two at the same time and in the same places means the person feels the paintbrush while seeing the action elsewhere.
Normally, a person's brain associates the feeling of one's hand with the sight of the hand. But the brain can be confused by a trick like this and start to think the rubber hand is the one it should pay attention to.
For the infants, the test was very similar. Again, a paintbrush was used, but this time the researchers stroked the babies' cheeks as they watched a video of the same thing happening to another baby.
The researchers tested how the babies behaved when the paintbrush was touched at different times and at the same time on their faces. Since babies can't talk, their researchers gauged the babies' reactions by measuring how long they looked at the baby in the video, Filippetti says.
"A longer looking time for a stimulus compared to another one is a measure of discrimination and preference for that stimulus," she tells Shots.
The newborns did watch the other baby in the video longer when the paintbrush strokes on both happened simultaneously, rather than at different times, or not at all. That response to simultaneous stimulation shows a sense of body awareness and ownership, the researchers say. Here's a video of how the test went.
The researcher also performed a second experiment with a twist: They showed the babies the same video turned upside down. The babies tested didn't respond to the simultaneous paintbrush strokes.
The study was published Thursday in Current Biology.
Filippetti concedes that her tests don't prove with absolute certainty that the infants identified themselves. But she says the work suggests that "the same factors known to be involved in body awareness in adults are present at birth."
Filippetti says that understanding the typical development of self could someday lead to insights into atypical developments, such as autism spectrum disorder.
For the babies in the experiment, a long nap was probably a richer reward than any contribution to science they might have made.