London: Babies have a conscious experience of the world and are capable of storing memories from as early as five-months-old, a new study has claimed.
Babies have long been considered as beings with limited skills and behaviours that are principally automatic and of a reflex type, and are not accompanied by a subjective conscious experience.
Scientists at the National Centre for Scientific Research (CNRS) in Paris, working in collaboration with scientists from NeuroSpin (Inserm/CEA) have now shown that as from an age of 5 months, infants are endowed with form of consciousness similar to that seen in adults.
Scientists used an alternative approach which consisted in determining whether the neural markers of consciousness seen in adults might also be present in babies.
Recent research in adults has revealed a two-stage response by the brain to the perception of an external event.
During the first 200 to 300 milliseconds, perceptual processing is wholly unconscious and accompanied by neural activity that increases in a linear manner - according to an amplitude which increases constantly depending on the length of time the objects are presented to them.
A later, second stage is characterised by a non-linear response corresponding to the threshold of consciousness, researchers said in the study published in journal Science.
Only periods of presentation that are sufficiently long to reach this threshold will give rise to a later response and be accompanied by conscious perception. This late and non-linear response by the brain is considered to be a neural marker of consciousness.
During the study, the presence of this marker of consciousness was tested in 80 infants aged 5, 12 and 15 months.
They were asked to look at faces presented to them for varying periods of time (or in other words, for periods shorter or longer than their threshold of perception), while the electrical responses of their brains were recorded.
In all the age groups, scientists saw the same late and non-linear response as in adults, thus confirming the presence of this "neural signature of consciousness" in the babies.
However, although this response is recorded at around 300 ms in adults, it occurred much later in the babies, only being established after at least a second in the youngest infants.
Researchers concluded these findings reveal that the cerebral mechanisms underlying perceptive consciousness are already present at a very early stage in infants.
However, at that time they are relatively slow, before accelerating gradually during development.