April 11 (UPI) -- In the first six months of life, babies can draw correlations between visual and vocal cues.
Before infants can talk, they use posture, voice and facial expressions to communicate their emotions. New research suggests babies can also interpret emotional cues.
Previous studies have found babies show a preference for happy faces and voices during their first six months of life, and can differentiate between the vocal and visual expressions of happiness from cues representing fear, sadness and anger.
But scientists at the University of Geneva in Switzerland wanted to know if babies really recognize emotions, or if they simply recognize the physical characteristics of faces or voices.
To find out, scientists presented 24 six-month-old babies with voices and faces expressing happiness and anger. First, the infants listened to 20-second clips of neutral, happy or angry voices while staring at a blank screen. Next, the babies were presented with 10-second visual clips of happy and angry faces.
Eye-tracking technology allowed researchers to analyze what the babies focused on when looking at the faces. When babies had previously heard a neutral or angry voice, they focused on each of the two faces equally. However, the babies spent longer looking at the mouth of the face expressing anger if they had previously heard a happy voice.
"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," researchers wrote in a news release.
The researchers published their findings on Wednesday in the journal PLOS One.
The study proves babies as young as six-months-old can transfer information from the auditory mode to the visual when interpreting emotional cues, researchers say.