Disputed signs of consciousness seen in babies’ brains
Infants display neural responses linked to visual awareness by 5 months of age
By Bruce Bower
Babies’ brains emit electrical bursts that signal a budding awareness of the visual world by the time they are 5 months old, a new study concludes. But some researchers are skeptical that these neural surges correspond to conscious experience.
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From age 5 months to 15 months, the brain begins to develop the ability to register and remember sights, according to the research by cognitive neuroscientist Sid Kouider of École Normale Supérieure in Paris and his colleagues. The researchers showed babies images that included faces flashed increasingly slowly on a screen. They started at a speed so fast that even adults wouldn’t consciously notice the images, and then the researchers increased the amount of time each image appeared. Infants displayed a sequence of rapid brain responses that first signaled unconscious and then conscious perception of faces, Kouider’s team reports April 18 in Science.
“We weren’t expecting to see any evidence of a neural marker for consciousness in 5-month-olds,” Kouider says. Babies at that age exhibited a weak, delayed version of a brain response that occurs when adults report seeing a face flashed just long enough to be consciously perceived, Kouider asserts.