Antecedents of Theory ofMind

This entire book, of course, is devoted to one approach to the question of antecedents: the role of parents. In this section I consider other possible contributors.

A 1994 article by Perner, Ruffman, and Leekam was the first to identify one potential contributor: namely, siblings. They reported a positive relation between number of siblings and false belief performance: the more siblings, the better the performance. The effect, moreover, was a fairly substantial one. The performance gap between children with no siblings and children with two siblings was equivalent to the gap between young 3-year-olds and old 4-year-olds.

Research since that reported by Perner et al. (1994) has provided a mixed picture. Some studies (e.g., McAlister & Peterson, 2013) have confirmed the sibling effect; others (e.g., Cole & Mitchell, 2000; Tompkins, Farrar, & Guo 2013) have failed to do so. In some studies (e.g., Ruffman, Perner, Naito, Parkin, & Clements, 1998) only older siblings have proved helpful; in other studies (e.g., McAlister & Peterson, 2007) siblings of any age have been shown to confer a benefit. A reasonable conclusion is that siblings are neither necessary nor always helpful for theory-of-mind development; in some cases, however, experience with siblings may accelerate the developmental process. Presumably, such experience does so because growing up with siblings provides experiences (e.g., pretend play, being teased, being tricked) that help children learn about the thoughts and feelings of others. Studies that have looked directly at how siblings interact (e.g., Dunn, 1999; Randell & Peterson, 2009) provide support for this conjecture. It has also been suggested that the effects of siblings may be in part indirect, in that the presence of multiple children in the family may affect both parenting and children’s experiences of parenting. This is a possibility that I return to in Chapter 7.

Siblings and parents are not the only possible sources for developmentenhancing experiences. Family size in general has been shown to relate to theory-of-mind development (Lewis, Freeman, Kriakidou, Maridaki-Kassotaki, & Berridge, 1996). Experience with peers can also contribute (e.g., Jenkins & Astington, 1996; Wang & Sue, 2009), as can experience in school (Pillow, 2012) and exposure to storybooks and children’s movies (Mar, Tackett, & Moore, 2010).

The discussion thus far has concerned various social agents and social experiences that can affect theory-of-mind development. Another approach to the antecedents question attempts to identify prerequisite abilities—that is, skills that must be in place for theory-of-mind understanding to emerge or to be expressed. Two presumed prerequisites have proved to be important.

One is language. A large research literature is quite consistent in demonstrating positive relations between language and theory of mind: On the average, children with advanced language skills are also more advanced in theory of mind (Milligan, Astington, & Dack, 2007). Although most of the evidence concerns first-order abilities, similar relations have been shown for higher- order developments, such as second-order false belief (e.g., Hasselhorn, Mahler, & Grube, 2005). No single aspect of language has emerged as critical; rather a variety of measures have proved predictive. The Milligan et al. (2007) meta-analysis surveyed five general categories of measures, all of which related significantly to theory of mind: syntax, semantics, receptive vocabulary, memory for sentential complements, and overall language ability.

The second presumed prerequisite is executive function. Executive function is an umbrella term for general problem-solving resources (e.g., inhibition, planning, working memory) that contribute to performance in a variety of cognitive domains. Among the cognitive domains for which executive function has been shown to be predictive is theory of mind, especially performance on false belief tasks: Children who are relatively advanced in executive function tend to do better on false belief (Devine & Hughes, 2014). The ability to inhibit a dominant response appears to be especially important in this regard (Moses, Carlson, & Sabbagh, 2005). This finding makes sense: To attribute a false belief, the child must inhibit the tendency to respond on the basis of what he or she knows to be the true state of affairs.

Although I have divided the discussion of antecedents into social agents and prerequisite skills, these two kinds of contributors are of course not independent of each other. Clearly, children’s language skills depend on the social agents with whom they have interacted, and in the typical case the most important of these agents are the child’s own parents. One way, therefore, that parents contribute to theory of mind is by nurturing the language skills that underlie the emergence and expression of theory-of-mind competence. Beyond such general parental support, research suggests that particular forms of verbal input from parents may be especially helpful in teaching children about the mental world. This research is discussed in Chapter 7.

What about executive function? Behavior genetics studies indicate that there is a substantial genetic contribution to individual differences in executive function (Friedman et al., 2008), which, of course, is an effect of parents but not of parenting. Differences among children are not solely genetic in origin, however, and recent research indicates that parental practices can make a definite contribution (Fay-Stammbach, Hawes, & Meredith, 2014). In Chapter 3 we will see that a particularly effective form of parental teaching is an approach called scaffolding: a flexible, contingent mode of instruction that adapts continually to the child’s level of understanding. A relatively high use of maternal scaffolding is positively associated with the development of executive function skills (Bibok, Carpendale, & Muller, 2009). In the other direction, various indices of family adversity relate negatively to executive function (Hughes & Ensor, 2009). Thus another way in which parents contribute to their children’s theory of mind is through their influence on the development of executive function.