Antecedents and Consequences
The discussion to this point has concerned what develops in theory-of-mind development. I turn now to the two other questions that research seeks to answer: Where do these developments come from, and what effects do they have on other aspects of children’s development?
Some Preliminary Points
Theory of mind has both a normative aspect—developments that are universal across all typically developing children—and an idiographic aspect—ways in which children differ in their development. False belief, for example, is eventually mastered by all typically developing children; the speed with which it is mastered, however, varies across children.
Conceptually, the normative aspect of development is an important question with respect to both antecedents and consequences. We want to know, for example, why all typically developing children master false belief, and we also want to know how this mastery subsequently affects other aspects of their behavior and development. Empirically, however, we are dependent on individual differences among children to explore both antecedents and consequences. If a sample shows no variation in false belief success, then there is no way to determine where success comes from or what effects success has. This, of course, is just a general point about research: Both independent variables and dependent variables must show some variation (hence the term “variable”).
The research to be considered now, therefore, is individual-differences research, the question being where variations in theory of mind come from and what effects these variations have on other aspects of development. Conceivably, individual differences of a variety of sorts could be explored (e.g., the certainty with which the knowledge is held, the ease with which it can be applied, the breadth of application). In fact, in the great majority of studies the only individual differences that appear are differences in rate of development: Some children master the knowledge in question more quickly than do others. There are occasional exceptions; we saw one example earlier in this chapter in the work on sequences of development, and I will note others as we go along. The exceptions, however, are rare. In the concluding chapter I return to the issue of individual differences in theory of mind and possible alternatives to an exclusive focus on rate of development.