The first step in penetrating beyond the capacity to recognize the facial expression of emotion, is the generation of that same facial expression at appropriate moments. The key to this stage is the appropriateness of the expression.
Newborns respond to the sound of another child crying in turn with their own crying. Between 4 and 8 months a child will mimic the emotional facial expressions of their care giver. Piaget explains this phenomena by saying that ``infants can not differentiate themselves from their environment, thus they are imitating what they perceive'' [Piaget, 1962]. His claim that the infant is confusing the acts of others with her own, has been actively debated with many supporting and contradictory studies: Meltzoff and Moore 1983, Abravanel and DeYoung(1991), Legerstee(1991) Fontaine(1984) Hayes and Watson(1981), Koepke et all (1983) MeKenzie and Over(1983).
Piaget named such behavior `pseudo-imitations' because of the lack of intentionality. He thought of the expressions in newborns as a reflex rather than a true display of an emotion. Piaget views imitation as the bridge from the sensorimotor response to intelligence. When the child becomes proficient at imitation, she will begin to imitate internally, thereby forming a mental representation of the expression. This signals the internalization of the emotion, value, or belief. Internalization is exhibited as the ability of the child to imitate or reference something to which they have been previously exposed.
Piaget's studies concluded that children don't internalize or emphasize emotion until age seven. However these results are contradictory even to his own findings that the pre-conceptual child (aged 2 to 4) also achieves the capacity to form mental representations for absent things or events.
By four years of age, children attempt to talk themselves out of their frustration by trying to convince themselves that they did not want whatever it was they could not have, or, alternatively, attempt to remove the prohibition by persuading others that they should have the object they desire [Sigman and Capps, 1997].
This more sophisticated use of logic demonstrates a mastery of control over emotional expression. While mimicry is and important tool for understanding the emotional development of the child, it can not be used alone. Rather, in conjunction with physical and verbal cues (captured on video tape), their combination forms the measure of the child's developmental level. Specifically, part of the Affective Tigger project was designed to use these criterion to asses the child's ability, and found evidence corroborating the above conclusion, that it is during the beginning of the fourth year that children finally internalize their understanding of emotional expressions.