At every moment, the brain of young children, like the one of adults, receives information from a multitude of sensory detectors. Some of these sensors (vision, hearing) provide information about the presence of external stimuli, others about what is happening on the skin (touch, temperature) or in various mucous membranes (olfaction, taste), and others about the state of the body (balance, position and movement of joints, state of the viscera, etc.). How can children learn to manage all this sensory information in order to draw a coherent representation ?
A widely held view is that ‘intelligence’ (understanding) of a situation involves different levels of analysis: the selection and the organisation of information arriving in the primary sensory regions of the cortex, to determine salient information (Tang et al. (2016)); the involvement of the parietal lobe (associative cortex integrating information from different sensory modalities) which would be at the basis of abstraction processes, symbolic representation and the development of explanatory hypotheses; the frontal regions which would select these hypotheses and decide on appropriate strategies on the basis of this information; finally, the posterior part of the anterior cingulate cortex which would estimate errors in judgement and actions and would allow for a change of strategy in return.
By learning, children must therefore manage to make all these levels work to optimise their actions. Confronted with numerous sensory stimuli, young children must learn to sort, combine, organise and insert them into cognitive processing and action schemes that are as operational as possible. Children do this spontaneously, because they are equipped with all the mechanisms that enable them to discover the world around them, to memorise their experiences and to determine their relationship with the world. But the organisation of their environment by adults can greatly facilitate these acquisitions – as all parents and the educational world know well.
One of the fascinating features of the brain is its high capacity to create mental categories on the basis of sensory information. Various brain regions in the frontal cortex and anterior temporal cortex play a key role in these categorisation processes in adults (Garcin et al.(2018)). It is known that children are sensitive to sensory regularities in their environment from an early age (Saffran and Kirkham (2018)), which allows them to gradually create appropriate mental categories. The organisation of these categories allows them to create concepts (abstract representations of an element or a set of elements with common characteristics). These concepts are memorable, generalisable and predictive. Once these concepts are in place (allowing a generalisable abstract notion to be extracted from the raw and variable sensory information), children can learn to associate semantic descriptors provided by their environment.
We do not yet really understand how these categorisation processes develop with age. Subjected to an incessant flow of sensory information, how do children select the relevant information on which to base their knowledge? It seems that young children do not use the same criteria and strategies as adults. Some work suggests that when the sensory situation is multimodal (several senses are solicited) young children favour one sensory input and take little account of the other sensory inputs before a fairly advanced age (e.g. Burr and Gori (2012), Robinson et al.(2018)). One reason could be that the different sensory modalities, and the associated integrative circuits, are not at the same level of development. Another reason could be that the amount of multi-sensory data is too large for an exhaustive analysis of all the details: in a first step it is sufficient to take into account only the main features, even if, according to the needs, this means refining the categories in a second step.
Editor: Didier Trotier