Conference by Arnaud Leleu – “Learning to see with the nose”

The role of multisensoriality in infant development has always been debated in the scientific community. Do children develop each sense in isolation, before linking the information from each of them? Or is learning first multi-sensory, before the senses can function independently?

In this lecture, Arnaud Leleu, a teacher-researcher at the University of Burgundy, reveals recent work carried out in his laboratory that supports the second hypothesis.

The sense of smell: learning to see with the nose

This work looked at the influence that the sense of smell – a sense that is generally neglected in humans, but which is nevertheless highly developed in infants – can have on the development of visual perception, which is still very immature in young children.

Through a series of experiments carried out using electroencephalography (EEG), a painless technique that allows us to measure the electrical activity of the infant’s brain in real time, Arnaud Leleu shows us how a body odour that is socially relevant to the young child, the smell of his mother, shapes the way his/her brain learns to perceive faces.

For the infant, learning to perceive faces implies that the brain learns to distinguish between faces and other objects belonging to distinct categories, but also to group different faces, sometimes physically very different, within the same category. This is called face categorisation.

To measure this face categorisation in the brains of infants, they are exposed to rapid sequences of images representing many objects, both living and non-living. Images of various faces are inserted at regular intervals to isolate the brain response reflecting their categorisation using an approach called ‘frequency labelling’.

Infants recognise their mothers by their smell

Arnaud Leleu presents several experiments that reveal how the smell of the mother of a 4-month-old infant facilitates the categorisation of faces, whether natural (human) or illusory (objects resembling faces that lead to what is called pareidolia). He also shows how the facilitating effect of maternal odour gradually fades as the infant’s brain develops and has less difficulty categorising faces.
Through this lecture, we learn how an ‘early’ sensory system such as smell supports and guides the development of visual perception in the first months of life, with this interaction between the senses being particularly strong when the visual system is immature. This work thus highlights a mechanism that, based on multisensory experience, allows infants to interpret their environment and establish their first knowledge. This conference is made in French.

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