Sense of Physical Self Different in Adults, Children Believe in Magic

According to a new study published in Psychological Science, a journal of the Association for Psychological Science, children's sense of having and owning a body differs from that of adults, which indicates that our sense of physical self develops over time.

Senses including vision, touch and body orientation come together to inform our perception of having and owning a body. According to psychological scientist Dorothy Cowie of Goldsmiths, University of London and colleagues hypothesized that there might be age differences in how these processes come together. To test this, they relied on the "rubber-hand illusion," a well-known sensory illusion where participants put their left hand on the table but hidden from view. Instead of looking at their left hand, they look at a fake hand. The experimenter sits across the table and strokes the participant's left hand with a paintbrush while also stroking the fake rubber hand. When the paintbrush strokes are matched so that they occur at the same time and in the same place on the two hands, the participant will often feel as if the fake hand is her own, and perceive the touch she feels as arising from the brush she sees stroking

The idea was tested on children of three different age groups (4-5; 6-7; and 8-9 years old), as well as adult participants. After experiencing the stroking, the participants were asked to close their eyes and point with their right index finger under the table, so that it was directly underneath the left index finger of their actual hand, according to a press release.

Both children and adults were sensitive to whether the vision and touch cues used from stroking matched on the real and fake hands. And when they did match, all participants experienced the rubber hand illusion. Most drifted closer to the fake hand and farther away from their own hand when they were asked to point to their real hand.

However, children of all ages responded more strongly to the illusion than the adults did. The study shows that children rely more on seeing their body in order to detect their sense of physical self than adults, which shows the reliance on vision created a strong bias toward the fake hand that they were looking at.

These findings indicate that there are two distinct processes underlying the sense of the body that develop according to different timetables - the process driven by seeing touches on the hand develops early in childhood, while the process driven by seeing a hand in front of us doesn't fully develop until later in childhood.

Co-authors on this research include Tamar Makin of the University of Oxford and Andrew J. Bremner of Goldsmiths, University of London.

This research was supported by a grant from the European Research Council and an award from the Royal Society.