This chapter presents an overview of interesting scientific findings related to human haptic perception and discuss the usability of these scientific findings for the design and development of virtual environments including haptic rendering. The first section of the chapter deals with pure haptic perception whereas the second and third sections are devoted to the integration of kinesthetic information with other sensory inputs like vision and audition. Bresciani, J. P., Drewing, K., & Ernst, M. O. (2008). Human haptic perception and the design of haptic-enhanced virtual environments. In The Sense of Touch and its Rendering (pp. 61-106). Springer, Berlin, Heidelberg.
This study investigates the influence of stimulus properties on movement control in active perception. We studied exploratory movement parameters in haptic perception of stimuli with different stiffness values. Virtual stimuli were generated using a PHANToM force-feedback device. Participants freely explored pair-wise presented stimuli and were asked to select the softer one. Afterwards we analyzed their exploratory movements considering the parameters velocity, pressure and the indentation depth. We found a systematic influence of stimulus' stiffness on pressure/indentation depth and velocity. We conclude that observers adapted the movement parameters depending on stiffness variations. We discuss whether such adaptation might serve to optimize perception, extending optimal observer models known from vision towards active touch. Kaim, L., & Drewing, K. (2008). Observers vary movement parameters in active touch depending on stimulus stiffness. Perception ECVP abstract, 37, 49-49.
This chapter examines the application of a psychophysical evaluation technique to quantify the fidelity of haptic rendering methods. The technique is based on multidimensional scaling analysis of similarity ratings provided by users comparing pairs of haptically-presented objects. Unbeknownst to the participants, both real and virtual deformable objects were presented. In addition, virtual objects were either rendered under high fidelity condition or under lower-fidelity condition in which filtering quality was reduced. The analysis of pairwise similarity data provides quantitative confirmation that users perceived a clear difference between real and virtual objects in the lower-fidelity, but not in the higher-fidelity condition. In the latter, a single perceptual dimension, corresponding to stiffness, sufficed to explain similarity data, while two perceptual dimensions were needed in the former condition. Harders, M., Leskovsky, P., Cooke, T., Ernst, M. O., & Szekely, G. (2008). of Book: The Sense of Touch and its Rendering: Progresses in Haptics Research. Springer.
The active control of exploratory movements is an integral part of active touch. In two experiments we investigated (and manipulated) the relationship between the haptic discrimination of small bumps and the direction of exploratory movements relative to the body. Shape discrimination performance systematically varied with the direction of stimulus exploration. Further, if they were rewarded for good perceptual performance and had the choice, participants displayed clear strategic preferences for certain exploratory directions. Chosen directions, at least on average, were accompanied by low discrimination thresholds. Overall, the findings emphasize the necessity to focus at the explorator’s active contribution to haptic perception, and provide the first hints that exploratory behavior might be exploited to optimize haptic perception. Drewing, K. (2008, June). Shape discrimination in active touch: Effects of exploratory direction and their exploitation. In International Conference on Human Haptic Sensing and Touch Enabled Computer Applications (pp. 219-228). Springer, Berlin, Heidelberg.
