Haptic exploration in the presence of vision.

Two experiments addressed initiation of haptic exploration to encode object properties when vision is present. Ss compared pairs of objects on designated properties, using only vision or with touch permitted. Tough initiation, reach, contact, and visual responses were timed. With difficult material judgments, tough occurred frequently and was initiated faster than the time to respond by vision alone. With geometric judgments, touch was rarely used and then was initiated at the typical time for a visual response. Imposing a visual preview before allowing touch did not reduce the incidence of touch but did speed its initiation. Results support a model in which preliminary visual processing quickly initiates haptic exploration for material judgments that are visually or semantically difficult.