Haptic Conservation of Amount in Blind and Sighted Children: Exploratory Movement Effects1

The present study compared blind and sighted children's haptic exploratory movement styles while performing conservation of solid amount judg-ments. The purpose was to examine the possibility that exploratory hand movements might provide an index to the occurrence of centrated or decen-trated attention in haptic conservation, as seems to occur with eye move-ments in visual conservation. Blind children showed more sophisticated hand movements than sighted children, and blind conservers frequently used strategies that decentered haptic attention. However, the blind children still showed a 3.5-year average delay in the appearance of the con-servative response compared to sighted children. Considerable evidence from studies of concrete operational thought in blind children suggests significant developmental delays in the onset of certain conceptual functions, including conservation, sedation, and spatial reason