Using numbers strategically: Proportional reasoning induces wealth in-group bias in an equity task

Prior work in cognitive development has shown a strong association between our numerical cognition abilities and our abilities to engage in equity-based social evaluation. At the same time, work in social development has found that children generally prefer wealthier others and prefer in-group members. Integrating these two perspectives, we investigated whether children’s developing proportional reasoning skills might help overcome their in-group preferences, or alternatively, to enact them. In a social evaluation task (modeled after McCrink et al., 2010), 4–8-year-olds viewed a series of characters with different resource constraints (e.g., one character had 2 cookies and another had 6), each of whom then shared a proportion of their resources with a friend (e.g., one character shared 1/2 of his cookies while another shared 2/6). Children were then asked to make a series of social evaluations about the characters. We also assessed children’s proportional reasoning skills, cognitive control, and subjective social status. Children’s proportional reasoning skills prompted them to select their wealth-ingroup members: High-income children were more likely to select the richer participant if they had high proportional reasoning skills, whereas low-income children were more likely to select the poorer participant if they had high proportional reasoning skills. Results suggest that proportional reasoning abilities help enact strategic in-group bias.