“So go, go, go, little dolls”: If your 5-month-old seems to have trouble following the movements of your two hands in sequence, it’s normal. In infants, the conscious perception of the environment is six times slower than in adults. According to the work of a team from Lyon, the first of its kind in the world, one has to wait until the age of 3 before the ability to switch from one stimulus to another is about as fast as in an adult. The study was published in the journal Current Biology.
The alert blink, that temporary blindness of the brain
Looking at a photo with two faces, it is impossible to analyze them all at once. You perceive the presence of these faces simultaneously, but to know who they are you have to process them one by one. Our brain proceeds in two stages to consciously perceive an external stimulus. The first is a sensory and unconscious phase that can integrate several stimuli in parallel (the brain perceives the presence of the two faces). Then comes the conscious processing of the stimulus, which relies on limited attentional resources (here is a photo of your son and a friend of his next to him).
During this second phase of conscious processing, it is impossible to perceive a new stimulus: researchers call this the attention blink. “It is a perceptual bottleneck, which means that for the brief time it is busy processing a first stimulus, the system is blind to a second stimulus—just like the blink of an eye blinds us for a moment“, explains the researcher Jean-Rémy Hochmann, first author of this work. Of course, this attention blink is very brief, lasting only a few hundred milliseconds in adults.
But with the baby, it’s a whole different story. “Alert blinking has been known in adults since the 1990s, and we also know that it exists in monkeys, but when we started the study there were no results demonstrating its existence in babies.“, specifies Jean-Rémy Hochmann.