Characterizing Perceptual Differences Due to Haptic Exploratory Procedures: An MDS Approach

Previous work in real and virtual settings have shown that the way in which we interact with objects critically influences their perceptual representation. This paper provides new, quantitative evidence that the exploratory procedure used in haptic interaction with a set of objects changes the way they are represented in the brain. Subjects rated similarity on a set of nine novel, 3D objects after either following their contours, laterally rubbing their centres, gripping them, or sequentially touching their tips. A multidimensional scaling (MDS) technique was used to analyze the similarity data. The analysis showed that subjects were able to recover the topology of the input parameter space and perceived its dimensions as shape and texture. A large amount of variability in the way subjects weighted dimensions was found for all procedures except lateral motion, in which the texture dimension strongly dominated shape. The results provide clear evidence that using different procedures changes the relative perceptual weighting of object properties, but that even when exploratory procedures are strictly controlled, there can be large individual differences in the weightings of object properties. Our MDS-based analysis framework can be used to visualize and quantify perception under various real-world scenarios. In addition, this paper discusses its use as a benchmarking and validation paradigm for haptic rendering and virtual environments in general.