Preschool children's understanding of the desire and knowledge constraintson intended action

In two experiments, 3-, 4- and 5-year-olds were tested on their ability to distinguish between intended and unintended actions on the basis of che age nt's desire (wanting vs. not wanting the outcome) and/or the agent's knowle dge state (having vs, not having the relevant knowledge co intend the outco me). Whereas all age groups had little difficulty imputing intention oh the basis of desire, only about one-half of 3- and 4-year-olds were able to im pute intention on the basis of knowledge; mastery of this latter aspect of intention understanding was not in place until after the age of 5 years. Wi thin-subjects analyses confirmed these findings fully, and also showed chat children were able to attribute ignorance and false beliefs on the basis o f a lack of perceptual access before they were able to make judgments of in tent on the basis of an agent's knowledge state. The relative lag in young children's appreciation of the knowledge constraints on intended actions is discussed in terms of cognitive, linguistic and social factors.