Perceiving heaviness by dynamic touch: An investigation of the size-weight illusion in preschoolers

This study investigates preschoolers' ability to perceive the heaviness of objects by dynamic touch, a perceptual system that relies on the use of the muscle as a sensory organ. In total, 18 preschoolers were asked to hold objects by a handle without being able to see them. The 9 objects differed in mass and volume, allowing us to test the size-weight illusion by dynamic touch. Children were asked in the context of a game to make judgments about the heaviness of the objects. Even the youngest children were sensitive to the rotational inertia of objects, a property that is commonly used by adults to determine the heaviness of an object. Rotational inertia is a function of both volume and mass. This suggests that the size-weight illusion in children is due not to a process of intermodal integration but to children's sensitivity to invariant properties of the input.