ABSTRACT
The second year is distinguished by at least four psychological competences that, although dissimilar in their surface features, may depend, in part, on the same, or similar, changes in the brain. The quartet of abilities includes (a) initial comprehension and expression of meaningful speech; (b) a capacity to infer selected mental and feeling states in others; (c) representations of actions that are prohibited, as well as encouraged, by adults together with an early understanding of the semantic concepts “right,” “wrong,” “good,” and “bad”; and (d) the conscious awareness of some of self’s feelings and intentions. The close temporal correspondence in the time of emergence of these four functions, usually between 12 and 24 months, suggests that they share a set of biological features that are necessary, but not sufficient, for their actualization.
