For everyone who has ever wondered what goes on inside an infant’s little fuzzy head, new research shows that babies display glimmers of a conscious awareness of the world and memory as early as 5 months of age.
Studies on adults show a particular pattern of brain activity: When your senses detect something, such as a moving object, the vision center of your brain activates, even if the object goes by too fast for you to notice. But if the object remains in your visual field for long enough, the signal travels from the back of the brain to the prefrontal cortex, which holds the image long enough for you to notice. Scientists see a spike in brain activity when the senses pick something up and another signal, the “late slow wave,” when the prefrontal cortex gets the message.
Researchers in France wondered if such a two-step pattern might be present in infants, monitoring their brain activity through caps fitted with electrodes. More than 240 babies participated, but two-thirds were too squirmy for the movement-sensitive caps. The remaining 80 were shown a picture of a face on a screen for a fraction of a second.
Cognitive neuroscientist Sid Kouider of CNRS, the French national research agency, watched for swings in electrical activity in the babies’ brains. In those who were at least a year old, Kouider saw a pattern similar to an adult’s, but it was about one-third as fast. The 5-month-olds also showed a late slow wave, although it was weaker and more drawn out than in the older babies. This may indicate conscious thought, Kouider and colleagues reported online last week in the journal Science. The wave suggests that the image is stored briefly in the baby’s temporary “working memory.” And consciousness, Kouider says, is composed of working memory.