Abstract: Young children’s deontic reasoning has been abundantly addressed by developmental psychologist since Wason Selection Task was simplified to explore the development of children’s reasoning ability. It has been found that children around 2 to 3 years of age can make different judgments toward violations in moral and conventional domains. In the mean while, researches on children’s Theory of Mind development also boomed. These studies, to some extent, all seemed to support the domain specific theory of children’s cognitive development. In a recent research by Liu, Fang, & Keller (2003), children’s deontic reasoning was explored in conditional promises between mom and her child such as, “if you dress yourself everyday this week, mom will take you to the zoo on Sunday”. In their task with vignette, both mom and her child knew about the other’s action before the contract was due. In Keller, Gummerum, Wang, & Lindsey (2004)’s study, however, both sides in the contract had no idea what the other was doing during the contract period. The ignorant deontic reasoning paradigm of Keller et al (2004) was deemed to be simpler in procedure and related to children’s theory of mind development, thus was used in combination with the rule content of morality and social conventions, affirmative or inhibitive, to explore young children’s deontic reasoning and have a tap on the domain specificity of children’s cognitive development. Ninety-six 4-, 5-, and 6-year-olds (48 girls) were randomly selected from an ordinary kindergarten of Xuzhou, Jiangsu Province, who was organized into three age groups: 3-year-olds, Mean age =4.03; 4-year-olds, Mean age =4.93; 5-year-olds, Mean age =5.94. They were tested individually by telling stories accompanied by illustrations. Results show that: 1) Similar developmental trends and role effects were found in preschoolers’ deontic reasoning of both moral rule and conventional rules, that is, most preschoolers can detect the peer (the child protagonist in the story) violation in the contract, and percentages detecting mother’s and bilateral violation increase with age. In particular, some of 4-year-olds detected mom’s violation successfully, and even some of the 5-year-olds detected bilateral violation. 2) Under the paradigm of ignorant deontic reasoning, many 4-year-olds falsely reported that the protagonist violated the contract under the circumstances mother was the true violator, and many 6-year-olds falsely reported that mother violated the contract under the circumstances the protagonist was the true violator. 3) Though preschoolers’ deontic reasoning of moral rules and conventional rules showed similar pattern, significant differences were observed between their reasoning about affirmative social rules and inhibitive social rules. 5- and 6-year-olds’ detection of peer’s violation in inhibitive moral rules is significantly lower (around 56%) than that in affirmative moral rules, whereas 6-year-olds’ detection of mother’s violation in bilateral violating situations in inhibitive moral rules is rather higher. 6-year-olds’ deontic reasoning of conventional rules showed similar differences caused by affirmative or inhibitive rules. These findings excelled some conclusions of previous studies, and indicated both the generality across domains and the specificity within domains in preschoolers’ deontic reasoning of moral and conventional rules.

Key words: moral, convention, deontic reasoning, preschoolers, theory of mind