Haptic and visual dimensions of perceived softness

Abstract

Exploring the environment with our senses is a prerequisite to successfully and efficiently interact with it. Our senses provide information about what material objects and surfaces are made of and help us to stay clear of icy patches or using the right grip of force when grasping an oily bottle. Compared to other material properties, the perception of softness has received only limited attention in the haptic and visual perception studies. Moreover, in the haptic domain, softness had been thought of synonymously with compliance. Yet, softness can have many dimensions: the softness of silk and jelly are quite different. Although silk and jelly comply with the force that is applied to them in a similar manner, the perception of softness for these compliant materials are quite different. Using a rating task we investigate here the haptic dimensions of perceived softness and compare it to the haptic dimensions derived from vision only. Results of an exploratory factor analysis suggest that for our set of stimuli, softness has indeed more than one qualitative dimension, i.e. compliance, to it. However, factor loadings were more distinct for the haptic domain. Haptic and visual domains provided rather similar information regarding slipperiness, softness, deformability and roughness. There were, however, differences between the two perceptual domains for granularity, stickiness and hairiness. We discuss these results with respect to the role of haptic and visual information in the perception of softness.