Age-related changes in children's use of external representations

This study explored children's use of external representations. Experiment 1 focused on representations of self: Self-recognition was assessed by a ma rk test as a function of age (3 vs. 4 years), delay (5 s vs. 3 min), and me dia (photographs vs, drawings). Four-year-olds outperformed 3-year-olds; ch ildren per formed better with photographs than drawings; and there was no e ffect of delay. In Experiment 2, 3- and 4-year-olds used a delayed video im age to locate a sticker on themselves (self task) or a stuffed animal (othe r task). The 2 tasks were positively correlated with age and vocabulary par tialed out. Experiment 3 used a search task to assess whether children have particular difficulty using external representations that conflict with th eir expectations: 3- and 4-year-olds were informed of an object's location verbally or through video; on half of the trials, this information conflict ed with children's initial belief. Three-year-olds performed worse than 4-y ear-olds on conflict trials, indicating that assessments of self and other understanding may reflect children's ability to season about conflicting ex ternal representations.