1 Answer

I couldn’t find a specific age but I did find this on WIKI:  

Boone and Cunningham conducted a study^[88] to determine at which age children begin to recognize emotional meaning (happiness, sadness, anger and fear) in expressive body movements. The study included 29 adults and 79 children divided into age groups of four, five and eight year olds. The children were shown two clips simultaneously and were asked to point to the one that was expressing the target emotion. The results of the study revealed that of the four emotions being tested the 4-year-olds were only able to correctly identify sadness at a rate that was better than chance. The 5-year-olds performed better and were able to identify happiness, sadness and fear at better than chance levels. The 8-year-olds and adults could correctly identify all four emotions and there was very little difference between the scores of the two groups. Between the ages of 4 and 8 nonverbal communication and decoding skills improve dramatically.