Detection of elasticity as an invariant property of objects by young infants

Three-month-old infants were habituated to two different motions of deformation, presented 'live' with an object of sponge rubber. After habituation, one-third of the subjects was presented with a third deforming motion; one-third was presented with a rigid motion of the same object; and the other third was presented with a continuation of the habituation sequence. The group presented with a rigid motion dishabituated, exhibiting a sharp increase in looking time. The other two groups showed little or no increase. These results suggest that infants perceive elasticity of substance, in contrast to rigidity, as an invariant property of an object over different deforming motions.