Scientists from University of Tampere studied how the infants, between 5-7 months, react to negative facial expressions. They found that infants aged 5 months react very differently to a fearful face than those aged 7 months.
"At the age of 7 months babies will watch a fearful face for longer than a happy face, and their attentiveness level as measured by EEG is higher after seeing a fearful than a happy face," said Mikko Peltola, researcher at the University of Tampere.
"By contrast, infants aged 5 months watch both faces, when they are shown side by side, for just as long, and there is no difference in the intensity of attention in favour of the fearful face," Peltola added.
The researchers believe that important developmental changes take place in the way that infants process significant emotional expressions
A fearful face attracts intense attention by the age of 7 months. In addition, it takes longer for infants to shift their attention away from fearful than from happy and neutral faces.
"Our interpretation of this is to suggest that the brain mechanisms that specialise in emotional response and especially in processing threatening stimuli regulate and intensify the processing of facial expressions by age 7 months," said Peltola.