In the second year of life children are able to self-objectify. This ability makes it possible to experience empathy and to understand another person's emotional or intentional state by vicariously sharing this state. We showed that the ability to identify empathetically with another person and draw a clear-cut distinction between the emotional domains of self and other develops synchronously with the ability to recognize oneself in the mirror.
In the fourth year of life children develop the ability to reflect upon mental states of themselves and others (Theory of Mind). This, along with the ability to represent reality on an imaginary basis, in addition to perceptive representation, enables humans to go on a "mental time travel". This means being able to represent oneself at every possible instant in the past and in the future and to imagine the desires and motives at each of those instants independently of one's present motivational state ("Bischof-Köhler-hypothesis"). Mental time travel has fundamental implications for planning of the future and recapitulation of the past.
Between the ages of 4 and 6, the relationship between children and their parents changes. This prompted Freud's concept of the "Oedipal phase". Other than Freud, we see the emotional state of unrest at this age as a consequence of the emergences of several seemingly unrelated competences: the use level-II perspective taking (theory of mind), the use of a temporal buffer to anticipate non-actual motivational states (mental time travel), the consolidation of gender constancy, and a differentiation of children's affective attitude toward their parents.
Literature in English:
Zmyi, N. und Bischof-Köhler, D. (2013) The development of gender constancy in early childhood and its relation to time comprehension and false-belief understanding. Journal of Cognition and Development 16(3), 455-470.
Bischof-Köhler D. & Bischof N. (2007). Is mental time travel a frame-of-reference issue? Open peer comment to: Suddendorf T. & Corballis M.C.: The evolution of foresight: What is mental time travel and is it unique to humans? Behavioral and Brain Sciences 30(3), 316-17.
Based on current knowledge, socio-cultural influences cannot entirely explain gender-typical behavior. The understanding of the relationship of nature and nuture is too simplistic, however, and leads to resistance against the possibility of inherent gender differences. We look at possible inherent factors more closely and analize them in reference to evolutionary biology.