Tactual Perception Experiments And Models

Results of five studies on tactual perception, involving airjet stimulators and a computer-controlled facility, are given. In the first study, alphabetic shapes were presented on an 8x6 airjet array that was translated in a small circle. The increased performance with movement suggests a hypothetical model that qualitatively accounts for the display motion effects. The second study involved pairs of alphabetic shapes presented in rapid succession at the same anatomical location. The interaction effects were: increased letter reversals for short interstimulus intervals; more first-response errors for short-stimulus onset intervals and more second-response errors for long-stimulus intervals; a crossover in first- and second-response error rates of 100 to 200 msec after onset of the first stimulus. In the third study, point airjet stimuli were applied simultaneously to the 24 interjoint regions of the fingers. The results suggest a tactile short-term memory with greater capacity than immediate-memory span but with 0.8-sec decay rate. In the fourth study, visual and tactile stimuli giving equal mean simple reaction times were used. With increased response alternatives, mean visual times increased less than mean tactile times; but with simultaneous presentation of both stimulus types, mean reaction time was much shorter than with either type alone.

This report describes basic studies on tactile perception and communication. In Section II are described experimental sessions in which words, sentences, and paragraphs were transmitted to subjects by a tactile display. Sessions in which a specially designed tactile alphabet was developed are discussed in Section III. Factors such as learnability, edge effects, letter packing, and number of fingers used are considered. Tactually naive subjects were able to identify these letters correctly at a rate of two random letters a second after 25 hours of practice. In Section IV, studies of two-dimensional compensatory tracking with a continuous visual display, a discrete visual display, and a discrete tactile display are described. Finally, in Section VI three series of quantitative studies are reported. The first is a study of the effect of deliberate stimulus pattern 'jitter' on performance. Next, a study concerned with methods of tactually transmitting the magnitude of a single analog parameter is described. Third, the theory of signal detection is applied to a study of the human observer's ability to discriminate among different loci of tactual stimulation.

This work forms part of the EU funded HAPTEX project, which is aimed at developing a VR system for the visual and haptic presentation of textiles. Written by experts in the field, the book presents the state-of-the-art of VR based tactile perception.

This book explains the mechanisms underpinning the tactile perception of electrovibration and lays the groundwork for delivering realistic haptic feedback on touchscreens via this method. Effective utilization of electrovibration can only be accomplished by simultaneously investigating both the physical and perceptual aspects of the finger-touchscreen interaction. Towards this goal, present work blends the available knowledge on electromechanical properties of the human finger and human tactile perception with the results of new psychophysical experiments and physical measurements. By following such an approach that combines both theoretical and experimental information, the study proposes new methods and insights on generating realistic haptic effects, such as textures and edges on these displays. Besides, state-of-the-art research on the field is reviewed, and future work is discussed. The presented interdisciplinary methods and insights can interest students, broad communities of haptics, neuroscience, engineering, physics, and cognitive sciences, as well as user-interaction experts and product designers from the industry.