Research
Babies combine scent of their mothers and vision to understand the world around them
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Freya Lucas
Aug 05, 2024
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Babies use both the scent of their mother and visual cues from their environment to make sense of the world, researchers have found, showing that this capability first emerges at four months of age.
While it has long been understood that humans combine sensory information to evaluate the world around them, particularly when one or more of their senses are insufficient on their own, it was, until now, less understood at what age this capacity developed.Researchers from the Université de Bourgogne, University of Hamburg, Université de Lyon, Institut Universitaire de France, Université de Lorraine, Centre Hospitalier de Nancy, and Centre National de la Recherche Scientifique (CNRS) tracked how and when French infants aged between four and 12 months of age use their mother's scent to perceive faces, publishing their findings in Child Development.
Results helped researchers confirm that the ability to perceive faces greatly improves between four and 12 months with younger infants benefitting the most from the presence of their mother's odour. The research also suggests that older infants efficiently perceive faces from visual information, and they do not need to rely on other concurrent cues anymore.
“In previous studies, we already showed that the rapid perception of faces, which are highly relevant visual inputs for infants, is shaped by another highly salient sensory signal for them, the mother's body odour,” Associate Professor Dr. Arnaud Leleu from the Université de Bourgogne explained.
“To do that, we relied on electroencephalography (EEG) and measured a face-selective neural response that is enhanced by the presence of the mother's odour in the 4-month-old brain.”
“Here, our aim was to determine whether this olfactory-to-visual facilitation declines gradually as infants grow and become more efficient at perceiving faces solely from visual information, as previously shown for other associations between two senses.”
Researchers tested 50 infants aged from 4 to 12 months, and found that the face-selective EEG response increases and complexifies between 4 and 12 months of age, indicative of improved face perception with development.
“As expected,” Dr Leleu continued, “we also found that the benefit of adding the mother's body odour diminishes with age, confirming an inverse relation between the effectiveness of visual perception and its sensitivity to a concurrent odor. Overall, this demonstrates that visual perception actively relies on odor cues in developing infants until the visual system becomes effective by itself.”
A surprising finding for the researchers was that the mother's odour has such a strong effect on the perception of various unfamiliar faces.
“Of course, we should further investigate the effect of other odours,” Dr Leleu said, “but interestingly, recent studies from other groups confirmed the special status of the mother's odour in infants by showing reduced reactions to fearful faces, higher attention toward an unfamiliar woman, and increased interbrain synchrony between the infant and that woman.”
“Thus, it seems like the mother's body odour reassures the infant and promotes their interest when they encounter novel people. In other words, this primary social odour that infants learn already in the womb seems to encourage prosocial cognitions and behaviours.”
Access the findings in full here. Dr Leleu’s quotes in this piece were drawn from a conversation held with The Society for Research in Child Development.
Find the full conversation here.
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