Perceiving the affordance of contact in four- and five-month-old infants.

The focus of this study was on the ability of infants to perceive whether an object is positioned at a distance that would make contact possible. As a toy was presented, sometimes within and sometimes beyond reach, the initiation of reaching and leaning forward was scored. Infants were divided into leaning and nonleaning groups. Both leaning and nonleaning 5-month-olds changed their behavior dramatically when the object was placed beyond, as opposed to within, reach. The nonleaners showed a decline in reaching when this boundary for contact was crossed. The "leaners" did not; rather, they began to lean forward. These results suggest that 5-month-olds use information for the affordance of contact. 4-month-olds provided less evidence that arm length regulates reaching. 5-month-old infants acted as if they not only had some sensitivity to the absolute distance of an object but also to the effect that leaning forward has on their ability to make contact with a distant object.