Abstract
In daily life, we can perceive the softness of objects through vision and touch: We can touch a rabbit’s fur, or we can visually perceive its softness by looking at a picture. Alternatively, watching someone else petting the rabbit, not only lets us see how the material reacts to touch but might also trigger us to experience hand motions and consequences of the interaction vicariously –possibly leading to a much more vivid experience of the fur’s properties. Previously, we have shown that different dimensions such as granularity, deformability, and viscosity underlie what we haptically perceive as being soft. Here, we investigate how these softness dimensions, compare to those available from static- and dynamic visual cues. Participants rated attributes of everyday materials, such as elasticity, velvety-ness etc. under three conditions: in the haptic condition, blindfolded participants explored and rated materials, while we recorded their hand movements. In the static visual condition participants rated the attributes on close-up images depicting the same materials, and in the dynamic visual condition participants performed ratings while viewing the videos recorded in the haptic condition. Principal component analysis revealed that the three perceptual spaces constructed from visual static, - dynamic, and haptic judgments were similar, in that each was comprised of a granularity, a viscosity, and a deformability dimension. However, only the dynamic visual condition yielded a furriness dimension, and only the haptic condition yielded a roughness dimension. Explained variance was higher for haptic and dynamic visual conditions than for the static visual one. Finally, Procrustes analyses revealed a high similarity between haptic and dynamic visual spaces, and only moderate similarity between static visual and haptic spaces and static visual and dynamic visual spaces. Taken together, these results suggest that dynamic cues available through haptic and visual exploration provide similar information about material properties.