Verbal deficits, which predict low academic achievement (e.g., Mayes & Calhoun, 2007; Wiese, Lamb, & Piersel, 1988) and school problems (e.g., Ackerman, Brown, & Izard, 2003; Ackerman, Smith, & Kobak, 2009), have been conspicuous in the research on violence. Some authors characterize verbal abilities as among the “most well-established neurocognitive impairments associated with conduct behavior problems” (Barker, Seguin, White, Bates, Lacourse, Carbonneau, & Tremblay, 2007; p. 593). Moffitt (1997) concludes from her own review of the empirical literature that “... verbal deficits of antisocial children are pervasive ...” (p. 132), even controlling for social disadvantage. Seguin et al. (2009) control for other neurcognitive abilities and find that frequent aggression is related to receptive vocabulary deficits. In their study, physical aggression problems were associated with language deficits, while hyperactivity problems were related to nonverbal deficits.
The mechanisms by which poor verbal ability affects antisocial behavior have been discussed extensively. Because communication is an important part of social interaction, deficits in this area would be expected to disrupt the development and maintenance of normal social relationships. Verbal ability has been said to promote “verbal mediation” of self-control and communication with others, which may help avoid interactions that lead to violence (Barker et al., 2007). Children with poor communication skills may receive more physical punishment and develop more troubled parent-child relationships. Verbal deficits make it more difficult to label emotions expressed by others and may limit the ability to respond verbally rather than physically. At least one study has demonstrated that verbal ability predicts self-control (Beaver, DeLisi, Vaughn, Wright, & Boutwell, 2008).
Moffitt (2006) theorizes that verbal cognitive deficits limit options for handling conflict. Language abilities are needed to process parent’s instructions and discipline (Moffitt, 1997b). Moffitt (1997b) sees poor verbal comprehension and expression as part of a larger set of neurological difficulties important for the development of persistent criminal behavior. She reviews numerous ideas about links between verbal deficits and antisocial behavior. For example, language abilities are needed to process parent instructions and discipline, and applying verbal labeling helps children classify sets of behaviors as wrong. Because language helps allow anticipation of consequences and creation of mental representations, it may help delay gratification and low verbal intelligence may thus lead to a present- oriented cognitive style.
Theory of mind appears to be closely linked with language development. Schneider, Lockl, and Fernandez (2005) found that performance on ToM tasks was strongly dependent on language proficiency in their sample. Sodian (2005) also emphasizes that language acquisition is “. by far the best predictor of theory of mind development ...” (p. 110). Cutting and Dunn (1999) found that variation in language ability explained the greatest amount of variation in emotion understanding in their sample of young children. They interpreted this finding to indicate that children’s language acquisition is very important for ToM development.