The development of end-state comfort planning in preschool children.

We investigated the development of the end-state comfort effect in young children. Fifty-one children from three age-groups (3, 4, and 5 years old) participated in the study. They performed the dowel placing task, which required them to reach for a horizontal dowel and to insert one of its ends into a target disk. Depending on which end was instructed, end-state comfort could be reached by picking up the dowel either with an overhand or with an underhand grip. All children reached for the dowel with an overhand grasp when this resulted in a comfortable end-state (i.e., thumb-up posture). A different pattern emerged when an underhand grip had to be selected. Here, 18% of the 3-year-olds, 45% of the 4-year-olds, and 67% of the 5-year-olds used an underhand grip and finished the action comfortably. For the first time, these results show a distinct pattern of gradual improvement in children's sensitivity to reach end-state comfort across three age-groups.