Young children's understanding of desire formation

Two studies examined preschoolers' appreciation of how mental states arise. In Study 1, children aged 3 to 5 (24 at each age) better understood percep tion-generated beliefs (e.g., that looking in a certain location generates a belief about the location's content) and attitude-generated desires (e.g. , that positive experiences with an activity generate a desire to partake o f the activity again) than physiology-generated desires (e.g., that not eat ing for a long time generates a desire for food). Ln Study 2, 4- and 5-year -olds (48 at each age) better understood the effects of quantity of experie nce (e.g., eating a lot vs, a little) than of time of experience (eating ju st now vs. a long time ago) on physiological states and desires. The findin gs suggest that whether children reason in more advanced fashion about desi res or beliefs depends on which aspects of these mental states are consider ed.