Dynamics of cup-to-mouth transport
Cup-to-mouth transport is a fundamental and adaptive behavior, but the spatial planning required for this skill has not been systematically studied. Bringing a cup to the mouth can be broken down into two spatial components: translations (displacement of objects) and rotations. Prior work on other spatial fitting tasks between objects (i.e. placing a rod into an aperture) suggests that children under two years have difficulty coordinating translations and rotations. In the following experiment, we investigate a related spatial problem with an object-body task in order to understand how infants coordinate translations and rotations when transporting a cup with a spout to the mouth. Infants between 10-24 months were presented a cup on a table in one of four possible orientations relative to the infant in counterbalanced order: spout facing left, right, opposite or toward the infant. We found that spatial planning behaviors varied as a function of age and the spatial properties of the task. Importantly, the results suggest that spatial planning during cup-to-mouth transport may follow a similar developmental pattern as spatial planning during environmentally directed tasks.