Alan M. Leslie

Psychologists and philosophers have recently been exploring whether the mechanisms which underlie the acquisition of ‘theory of mind’ (ToM) are best charac- terized as cognitive modules or as developing theories. In this paper, we attempt to clarify what a modular account of ToM entails, and why it is an attractive type of explanation. Intuitions and arguments in this debate often turn on the role of develop- ment: traditional research on ToM focuses on various developmental sequences, whereas cognitive modules are thought to be static and ‘anti-developmental’. We suggest that this mistaken view relies on an overly limited notion of modularity, and we explore how ToM might be grounded in a cognitive module and yet still afford development. Modules must ‘come on-line’, and even fully developed modules may still develop internally, based on their constrained input. We make these points con- crete by focusing on a recent proposal to capture the development of ToM in a module via parameterization.

We use a new model of metarepresentational development to predict a cognitive deficit which could explain a crucial component of the social impairment in childhood autism. One of the manifestations of a basic metarepresentational capacity is a ‘ theory of mind ’. We have reason to believe that autistic children lack such a ‘ theory ’. If this were so, then they would be unable to impute beliefs to others and to predict their behaviour. This hypothesis was tested using Wimmer and Perner’s puppet play paradigm. Normal children and those with Down’s syndrome were used as controls for a group of autistic children. Even though the mental age of the autistic children was higher than that of the controls, they alone failed to impute beliefs to others. Thus the dysfunction we have postulated and demonstrated is independent of mental retardation and specific to autism.

Do victims’ emotions underlie preschoolers’ moral judgment abilities? Study 1 asked preschoolers (n = 72) to judge actions directed at characters who could and could not feel hurt and who did and did not cry. These judgments took into account only the nature of the action, not the nature of the victim. To further investigate how victims’ emotions might impact children’s moral judgments, Study 2 presented preschoolers (n = 37) with stories that varied in transgression type (Moral, Conventional, or None) and victim’s reaction (Crying Present or Crying Absent). As in Study 1, children’s judgments were affected primarily by transgression type, and not by emotion. In an analogous task, judgments of children with autism spectrum disorders (Study 3; n = 12) were affected by both transgression type and crying. Typically developing children’s moral judgments are thus concerned primarily with action type, not with emotional displays, but the judgments of children with autism spectrum disorders can be swayed by victims’ emotions

Number concepts must support arithmetic inference. Using this principle, it can be argued that the integer concept of exactly ONE is a necessary part of the psychological foundations of number, as is the notion of the exact equality - that is, perfect substitutability. The inability to support reasoning involving exact equality is a shortcoming in current theories about the development of numerical reasoning. A simple innate basis for the natural number concepts can be proposed that embodies the arithmetic principle, supports exact equality and also enables computational compatibility with real- or rational-valued mental magnitudes