The Categorical Representation of Facial Expressions by 7-Month-Old Infants

We investigated the ability of 7-month-olds to categorize the facial expressions happy, fear, and surprise when these expressions varied both by the model depicting the expression and by how intensely the expression was portrayed in a series of three experiments. In Experiment 1, infants successfully discriminated a single model posing a mild versus an extreme version of happy and fear. In Experiment 2, infants categorized happy when depicted by for different models posing mild and extreme versions and discriminated happy from fear. In Experiment 3, infants categorized both happy and surprise posed by five models varying in degree of expressiveness and discriminated these expressions from fear. In both Experiments 2 and 3, there was no evidence that infants could also (a) categorize the fear expressions and discriminate fear from happy or from surprise or (b) discriminate surprise from happy after habituating to surprise. These results are discussed in the context of the importance of experience in recognizing facial expressions and of how such experience influences the ease with which various expressions can be encoded and discriminated from other expressions in the laboratory