“Gender-role stereotypes are well-ingrained cognitive schemes that we use to interpret and often distort the behaviour of males and females. People even use these schemas to classify the behaviour of infants. In one study (Condry & Condry, 1976), university students watched a video-tape of a 9-month-old child who was introduced as either a girl (“Dana”) or a boy (“David”). As the students observed the child at play, they were asked to interpret his or her reactions to toys such as a teddy bear or a jack-in-the-box. The resulting impressions of the infant’s behaviour clearly depended on his or her presumed sex. For example, a strong reaction to the jack-in-the-box was labelled “anger” when the child was presumed to be a boy and “fear” when the child was presumed to be a girl.”
Source: Developmental Psychology Childhood and Adolescence 3rd ed. Author: SHAFFER