Two systems for thinking about others’ thoughts in the developing brain

Abstract

Human social interaction crucially relies on the ability to infer what other people think. Referred to as Theory of Mind (ToM), this ability has long been argued to emerge around 4 y of age when children start passing traditional verbal ToM tasks. This developmental dogma has recently been questioned by nonverbal ToM tasks passed by infants younger than 2 y of age. How do young children solve these tests, and what is their relation to the later-developing verbal ToM reasoning? Are there two different systems for nonverbal and verbal ToM, and when is the developmental onset of mature adult ToM? To address these questions, we related markers of cortical brain structure (i.e., cortical thickness and surface area) of 3- and 4-y-old children to their performance in novel nonverbal and traditional verbal TM tasks. We showed that verbal ToM reasoning was supported by cortical surface area and thickness of the precuneus and temporoparietal junction, classically involved in ToM in adults. Nonverbal ToM reasoning, in contrast, was supported by the cortical structure of a distinct and independent neural network including the supramarginal gyrus also involved in emotional and visual perspective taking, action observation, and social attention or encoding biases. This neural dissociation suggests two systems for reasoning about others’ minds—mature verbal ToM that emerges around 4 y of age, whereas nonverbal ToM tasks rely on different earlier-developing possibly social-cognitive processes.

On the (lack of) association between theory of mind and executive functions: a study in a non-clinical adult sample

“…For example, Richardson et al 55 using fMRI show that in typically developing children (3-12 years) the ability to solve cognitive ToM tasks relies on the same brain network recruited when adults reason about others' mental states (i.e., medial prefrontal cortex, temporoparietal junction, and precuneus) and that over time this network gradually becomes more integrated and distinct from other networks. More importantly, combining white matter measures acquired by means of tract-based spatial statistics and probabilistic tractography with behavioural performance in false belief tasks, it has been recently demonstrated that the developmental breakthrough in false belief understanding in 3-and 4-year-old children is associated with age-related changes in local white matter structure in temporoparietal regions, the precuneus and medial prefrontal cortex, and that these effects are independent of co-developing EFs 29,56 . As suggested by Grosse Wiesmann et al 56 , these findings are inconsistent with the view that young children only fail explicit ToM tasks due to extrinsic executive demands of these tasks because, in that case, brain regions involved in EFs should be related to success in the tasks.…”

Testing the stability of theory of mind: A longitudinal approach

“…Interestingly, and in accord with previous research, verbal skills did not relate to performance on this task in contrast to the well-established link between explicit false belief tasks and language [ 73 ]. Furthermore, performance on implicit and explicit theory of mind tasks in childhood did not converge, suggesting that distinct cognitive processes underlie implicit and explicit false belief reasoning, as recently confirmed in a study showing dissociated brain regions involved in processing implicit and explicit false belief tasks [ 74 ]. The results are therefore compatible with a dual process view of implicit and explicit ToM which suggests an automatic, cognitively efficient (possibly unconscious) belief-tracking system already present in infancy, and an explicit more flexible but cognitively more demanding belief processing system, which develops later [ 12 , 29 , 75 , 76 ].…”

Maturational indices of the cognitive control network are associated with inhibitory control in early childhood

“…To obtain measures of cortical thickness and surface area, we used the preprocessed brain images from a recent study using the current dataset (Grosse Wiesmann et al, 2020 (Fischl & Dale, 2000). Surface area of the GM/WM boundary and cortical thickness, defined as the closest distance from the GM/WM boundary to the GM/CSF boundary, was calculated at each vertex.…”