How does maternal odor influence socioemotional processing in infancy?
General, Cognitive and Mathematical Psychology
Final Report Abstract
Humans are a born as social beings; from birth on, they possess a range of abilities that enables them to interact with other human beings around them. These abilities have long been investigated in the visual and auditory domain. Other sensory modalities however have largely been neglected. However, we know from other species that especially social odor plays a fundamental role in early development. Only in the past decade, first studies have started to explore the role of maternal odor for sociocognitive processes in early human development. The first study to demonstrate an influence of maternal odor on face processing was published by Durand et al. in 2013, who could show that infants look longer towards faces when they can smell their mother. The goal of the present project was to explore this influence in a more detailed way and move beyond the mere detection of faces towards the processing of facial information. Furthermore, by measuring EEG responses, we wanted to gain further insights into the neural bases underlying this effect. To do so, we conducted three EEG studies investigating the influence of maternal odor on face processing in 7-month-old infants. In the first study, we investigated the influence of maternal odor on the processing of facial emotions; infants were exposed to either their mother’s odor, an unfamiliar mother’s odor (control-group 1) or no particular odor (control-group 2) while watching happy and fearful facial expressions. We could show that infants in both control groups showed an age-typical enhanced neural response to fearful faces, which was absent when infants could smell their mother. Hence, maternal odor clearly impacts the processing of emotional faces, and might provide a safety signal, causing the infant to allocate less attention to signals of potential threat such as fearful faces. In the second study, we investigated (a) whether the influence of maternal odor is different for familiar compared to unfamiliar face and voice and (b) whether the influence we observe on a neural level is specific to social signals or can also be observed for familiar non-social stimuli such as an infant’s favorite toy. We found that infants who are exposed to an unfamiliar body odor show a stronger response to their mother’s face, while infants who smelled their mother did not respond differently to their mothers or an unfamiliar face. We did not find an influence of maternal odor on the processing of (a) non-social stimuli and (b) auditory information, suggesting a potential specificity of the observed effect to visual social information. In the third study, we were interested in whether the observed effects are specific to maternal odor or can also be found in response to the mother’s voice. To that end, we repeated the experiment from study 1, but rather than changing the odor context, infants heard either their mother or an unfamiliar woman read a children’s story. As for odor, we observed an influence of the mother’s voice on the processing of facial expressions. However, this effect was not as pronounced as the odor effect, suggesting that while both signals of maternal presence influence face processing, this influence may be stronger for odor. Taken together, results across three studies provide first evidence for the influence of maternal odor on the neural processing of facial information in infancy. Maternal odor appears to be a safety signal for the infant, modulating is perception of specifically social information. The precise pattern of this effect will have to be explored in future studies, addressing for instance potential developmental changes of this effect in the first year of life and the role of nonmaternal but familiar odor, such as paternal odor or odor of the home environment. In sum, this project provides evidence that in humans, just as in other species, maternal odor has a strong impact on early sociocognitive development.
Publications
- (2019). Quantifying individual auditory and visual brain responses in 7- month-old infants from watching a four-minute cartoon movie. NeuroImage, 202, 116060
Jessen, S., Fiedler, L, Münte, T., & Obleser, J.
(See online at https://doi.org/10.1016/j.neuroimage.2019.116060) - (2020). Maternal odor reduces the neural threat responses in human infants. Dev Cogn Neurosci, 45, 100858
Jessen, S.
(See online at https://doi.org/10.1016/j.dcn.2020.100858) - (2021). Neural Tracking in Infants – an Analytical Tool for Multisensory Social Processing in Development, Dev Cogn Neurosci, 52, 101034
Jessen, S., Obleser, J., & Tune, S.
(See online at https://doi.org/10.1016/j.dcn.2021.101034)
