ABSTRACT
An object affords grasping if its properties are compatible with the actor’s morphology, functional capabilities, and biomechanical constraints. In order to allow adaptive behavior to occur, certain object properties, such as size, must be perceived in the scale of the actor’s body dimensions. The absolute transition point at which the action mode changed was defined as the smallest cylinder diameter that exclusively required a two-handed pattern. Mean transition values were 8.42, 11.00, and 10.75 cm for the three groups, respectively. The quality of the transition was analyzed according to the number of cylinders that gave rise to ambiguous solutions, that is, the 1–2 and the 2–1 grasping patterns. Mean values were 1.66, 0.66, and 0.57 for the younger, intermediate, and older group. Although sharp transitions have been observed in adults, our results suggest that the sharpness of transition in children may be a part of an acquisition process that becomes stable during infancy, with little evolution after the age of five.
