Functional roles and cultural modulations of the medial prefrontal and parietal activity associated with causal attribution.

Causal understanding of physical events is culturally universal. However, behavioral studies suggest that how we perceive causality is culturally sensitive, with East Asian culture emphasizing contextual factors and Western culture emphasizing dispositional factors guiding causal relationships. The present study investigated potential neural substrates of the cultural difference in causal attribution of physical events. Using functional magnetic resonance imaging, Experiment 1 scanned Chinese subjects during causality or motion direction judgments when viewing animations of object collisions and identified a causal-attribution related neural circuit consisting of the medial/lateral prefrontal cortex, left parietal/temporal cortex, and cerebellum. Moreover, by manipulating the task demand of causal inference and the complexity of contextual information in physical events, we showed that the medial prefrontal activity was modulated by the demand to infer causes of physical events whereas the left parietal activity was modulated by contextual complexity of physical events. Experiment 2 investigated cultural differences in the medial prefrontal and left parietal activity associated with causal attribution of physical events by scanning two independent groups of American and Chinese subjects. We found that, while the medial prefrontal activity involved in causality judgments was comparable in the two cultural groups, the left parietal activity associated with causality judgments was stronger in Chinese than in Americans regardless of whether the contextual information was attended. Our findings suggest that causal inference in the medial prefrontal cortex is universally implicated in causal reasoning whereas contextual processing in the left parietal cortex is sensitive to cultural differences in causality perception.