I give you a cup, I get a cup: A kinematic study on social intention

When participants (Agents) performed a reach-to-grasp movement to give the target object, in presence of eye-gaze communication they reached the wrist׳s acceleration peak faster if the Other previously interacted with the second object in accordance with its conventional use. Consistently participants reached faster the MFA when the objects were related by a functional-individual than a functional-cooperative relation. The Agent׳s getting response strongly affected the grasping component of the movement: in case of eye-gaze sharing, MFA was greater when the other previously performed a manipulative than a functional grip. Results reveal that humans have developed a sophisticated capability in detecting information from hand posture and eye-gaze, which are informative as to the Agent׳s intention.