The ability of babies to differentiate emotional expressions appears to develop during their first six months. Researchers from the University of Geneva (UNIGE), Switzerland, have just provided an initial answer to this question, measuring the ability of six-month-old babies to make a connection between a voice (expressing happiness or anger) and the emotional expression on a face (again, of happiness or anger).
The findings, published in the journal PLOS ONE, show that babies look at an angry face - especially the mouth - for longer if they have previously heard a happy a voice. This reaction to something new demonstrates for the first time that babies have an early ability to transfer emotional information from the auditory mode to the visual.
The ability of babies to differentiate emotional expressions seems to develop in the first six months of life. During this period, new-borns and babies have a preference for smiling faces and happy voices. Prior to six months, they can distinguish happiness from other expressions such as fear, sadness or anger. From seven months onwards, they develop the ability to discriminate between several other facial expressions.
In an attempt to study this feature further, 24 six-month-old babies took part in a study at the Geneva BabyLab. They were exposed to voices and faces expressing the emotions of happiness and anger. During a first phase devoted to auditory familiarisation, the babies faced a black screen and listened to a neutral, happy or angry voice for 20 seconds. In the second stage -- based on visual discrimination lasting 10 seconds -- the babies were placed in front of two emotional faces, one expressing happiness and the other anger.
The research team used eye-tracking technology to measure the baby's eye movements with great precision.
The results of the study revealed that six-month-olds did not have a preference for either of the emotional faces if they had already heard a neutral voice or a voice expressing anger. On the other hand, they spent longer looking at the face expressing anger -- especially its mouth -- after hearing a voice expressing happiness. This visual preference for novelty on the part of six-month-olds testifies of their early ability to transfer emotional information about happiness from the auditory to the visual mode.
Based on this study, we can conclude that six-month-old babies are able to recognise the emotion of happiness regardless of these auditory or visual physical characteristics.