Stocks and flows (SF) are essential to every-day judgments: debt changes with rates of incomes and expenses, and body weight with calories consumed and energy expended. Research suggests that individuals with strong mathematical skills have a poor understanding of SF. However, past research used homogeneous participant samples and the relationship between mathematical knowledge and performance in SF tasks was not tested. In two studies involving different populations from China and the U.S.A, we find that individuals with better general mathematical knowledge tend to be more accurate in SF tasks. We find that most participants who make mistakes follow an erroneous correlation heuristic; however, we also find that the use of this heuristic is not related to mathematical knowledge. Our results open the door to new research questions, including the type of mathematical knowledge needed and the relationship of mathematical knowledge and cognitive processes that people need for solving SF tasks.

People's understanding of accumulation (stock) and of rates of change (flows) is essential to successful decision making in dynamic environments. However, past research suggests that highly educated Western people are often unable to infer the behavior of stock-flow systems. In an empirical study involving a population of university students in China, we tested whether mathematical knowledge, global-local processing and domain experience affect participants' performance in stock-flow tasks. We find that Chinese undergraduates had good performance in general, and individuals with more mathematical knowledge performed better on stock-flow tasks. We discuss the possible reasons that explain these participants' success. Future research needs to extend our work to more diverse populations across different cultures, nations and education systems. Comparative studies on the content of math education under a cross-cultural frame are desirable to uncover more essential factors for people's understanding of stock-flow structures.

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