Infants are less likely to respond to negative visual stimulation if they smell their mother. This was found out by a German neurologist, having studied the brain activity of seven-month-old children when viewing frightened and cheerful faces, putting next to them either a clean T-shirt or a t-shirt that had previously been worn by the child’s mother or a stranger. If the mother’s shirt was next to the baby, then the brain activity characteristic of the negative stimulus was not observed on the encephalogram.
At the first time after birth, the baby’s life is completely dependent on the mother, not only in matters of nutrition and safety but also in the mental state: babies become attached to those who take care of them in the first days of their lives and calm down when they are around. However, it is not always clear, however, whether the physical presence of the mother is necessary for the child to feel safe: for example, it is known that the brains of infants respond to the mother’s voice even at a very young age, and this stimulates its development.
Sarah Jessen from the University of Lubeck decided to check whether the mother’s smell could soothe the child. To do this, she studied the brain activity of 76 seven-month-old infants in response to visual stimulation using electroencephalography. Since babies can recognize emotions on people’s faces as early as six months, female faces have been chosen as stimuli either with frightened (negative stimulation) or joyful facial expression (positive stimulation).
During the experiment, infants were seated in a child seat in front of the screen, and a t-shirt was placed on top of them. Depending on the group (there were three in all), the T-shirt was either clean or worn: for this, Jessen asked either the mother or a stranger to the infant for three nights in a row before the experiment to sleep in the same T-shirt, and then provide it to the laboratory for an experiment.
The author studied the brain activity of infants with the help of electroencephalography: Jessen focused on the negative evoked potential Nc (Negative central – is recorded from the electrodes located in the middle of the frontal lobes), which appears in the interval between 400 and 800 milliseconds after the presentation of the stimulus and is recorded in infants during treatment visual information.
Scientists found that the Nc amplitude in the EEG was higher with negative stimulation (p = 0.001), that is, when babies saw frightened faces. It is more interesting, however, that in the case when the T-shirt that the mother used to wear was next to the baby. In other words, the smell of the mother led to the fact that the intensity of the reaction to a negative stimulus decreased significantly. Moreover, the reaction of the infants also depended on whether they were still breastfeeding: an increase in Nc was observed only in those children who were breastfed.
A similar reaction to the smell of the mother is known for many species of animals: for example, from laboratory studies, it is known that young rats feel calmer if they sniff their mother. For infants, however, this was shown for the first time, and it also turned out that such a reaction is regulated by breastfeeding – that is, apparently, the presence of constant close contact between the infant and its mother. The results of the work show not only that even the sense of smell can be used to calm the baby, but also that smell can be an important social signal for a person.
The infant’s response to the mother’s presence also depends on many other factors, but all of them are very important for the formation and maintenance of attachment.