Neuropsychologia 48 (2010) 1767–1774 Contents lists available at ScienceDirect Neuropsychologia journal homepage: www.elsevier.com/locate/neuropsychologia Dopaminergic functioning and preschoolers’ theory of mind Christine L. Lackner a , Lindsay C. Bowman b , Mark A. Sabbagh a,∗ a Queen’s University, Kingston, Canada b University of Michigan, Ann Arbor, USA article info Article history: Received 15 April 2009 Received in revised form 23 February 2010 Accepted 25 February 2010 Available online 4 March 2010 Keywords: Theory of mind Executive functioning Dopamine Developmental neuropsychology Social neuroscience abstract Representational theory of mind (RTM) development follows a universal developmental timetable whereby major advances in reasoning about mental representations occur between the ages of 3 and 5 years old. This progression appears to be only absent in the case of specific neurodevelopmental impair- ments, such as autism. Taken together, this suggests that neuromaturational factors may play a role in RTM development. Recent EEG work has shown that one neuromaturational factor pacing this universal developmental timetable is the functional maturation of medial prefrontal cortex. The neurotransmit- ter dopamine (DA) is thought to play a crucial role in typical frontal lobe development. Therefore, the goal of the present study was to investigate the role that DA may play in RTM development. Ninety- one 48–62-month olds were given a battery of RTM tasks along with EEG measurement. EEG recordings were analyzed for eyeblinks, a reliable indicator of DA functioning, and we calculated their average eye- blinks per minute (EBR). Regression analyses showed that EBR was associated with RTM after controlling for children’s performance on a Stroop-like measure, language ability, gender, and age. These findings provide evidence that DA functioning is associated with RTM in the preschool years, and are discussed with respect to how DA might provide a mechanism that helps to account for both neurobiological and experiential factors that are known to affect the timetable of preschoolers’ RTM development. © 2010 Elsevier Ltd. All rights reserved. Theory of mind is the understanding that human action is motivated by internal mental states such as beliefs, desires, and intentions. In the preschool period, children’s understanding of oth- ers’ minds appears to change rapidly. Specifically, children come to explicitly understand that others’ mental states, in particular their knowledge and beliefs, are person-specific representations of the world (Wellman, Cross, & Watson, 2001). This new under- standing is sometimes called a “representational theory of mind” (RTM), and is indexed by a canonical battery of tasks, including the false-belief task. Although recent research suggests that the ori- gins of this understanding may be present early in infancy (Onishi & Baillargeon, 2005), children’s ability to recruit these concepts to explain behavior in everyday settings seems to follow a more pro- tracted trajectory. What is perhaps most interesting is that the rapid changes in preschoolers’ RTM development have been observed across cultures with vastly different world views and across multi- ple variants of the same basic experimental paradigm (Wellman et al., 2001). One exception to this stereotyped developmental time course includes the neurodevelopmental disorder of autism, in ∗ Corresponding author at: Department of Psychology, Queen’s University, 62 Arch St., Kingston, Ontario, Canada K7L 3L3. Tel.: +1 613 533 2887; fax: +1 613 533 2499. E-mail address: sabbagh@queensu.ca (M.A. Sabbagh). which theory-of-mind reasoning is specifically impaired (Baron- Cohen, Leslie, & Frith, 1985). These findings taken together suggest that the timetable of RTM development may be constrained, at least in part, by neurodevelopmental factors, including perhaps neurochemical ones. The goal of this research is to test this hypothesis by examining the extent to which individual differences in dopamin- ergic functioning are associated with young children’s theory of mind. Dopamine (DA) is of primary interest in the present context for several reasons. First, recent electroencephalographic (EEG) research has shown that the functional development of the dorsal medial prefrontal cortex (dMPFC) is a specific neurodevelopmental correlate of preschoolers’ RTM development (Sabbagh, Bowman, Evraire, & Ito, 2009). The dMPFC is rich in DA receptors and lies at the end of the mesocortical dopamine pathway. DA affects cell proliferation in regions that receive DA projections, including the frontal cortex (e.g., Popolo, McCarthy, & Bhide, 2004). Given that cell proliferation is a critical neurodevelopmental process, these findings provide some reason to suspect that DA might play a criti- cal role in the healthy development and functioning of the dMPFC. Thus, we might expect DA to be associated with RTM development in preschoolers. A second and perhaps more intriguing reason to suspect a role for DA comes from a consideration of the role that DA plays 0028-3932/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.neuropsychologia.2010.02.027