Tactile Masking by Electrovibration

Abstract

Future touch screen applications will include multiple tactile stimuli displayed simultaneously or consecutively to single finger or multiple fingers. These applications should be designed by considering human tactile masking mechanism since it is known that presenting one stimulus may interfere with the perception of the other. In this study, we investigate the effect of masking on tactile perception of electrovibration displayed on touch screens. Through conducting psychophysical experiments with nine subjects, we measured the masked thresholds of sinusoidal electrovibration bursts (125 Hz) under two masking conditions: simultaneous and pedestal. The masking stimuli were noise bursts, applied at five different sensation levels varying from 2 to 22 dB SL, also presented by electrovibration. For each subject, the detection thresholds were elevated as linear functions of masking levels for both masking types. We observed that the masking effectiveness was larger with pedestal masking than simultaneous masking. Moreover, in order to investigate the effect of tactile masking on our haptic perception of edge sharpness, we compared the perceived sharpness of edges separating two textured regions displayed with and without various masking stimuli. Our results suggest that sharpness perception depends on the local contrast between background and foreground stimuli, which varies as a function of masking amplitude and activation levels of frequency-dependent psychophysical channels.

The Perception of Ultrasonic Square Reductions of Friction With Variable Sharpness and Duration

“…Promising rendering of bumps and holes has been implemented by mapping the shape geometry to the frictional force [20], [21], [27]. Important perceptual dimensions such as the perceived roughness [28], the pitch [29], or the pleasantness [30] of the signal can also be modulated by changing the waveform and frequency of the stimulation and the perception of frictional signals can be additionally modulated by a masking background noise [31]. Data-driven rendering of textures is also possible by replaying the acceleration or force signals elicited during tactile exploration of the natural textures [32], [33].…”

Electroadhesion for soft adhesive pads and robotics: theory and numerical results

“…The electrical attraction between a charged surface and a human finger was discovered by Johnsen and Rahbek. In 1953 Mallinckrodt et al [3] applied an alternating voltage to insulated metal electrodes and observed an alternating electrostatic force that periodically attract and release the finger from the surface; this is now denoted electrovibration [4][5][6][7], and forms the basis for electroadhesion based haptic devices such as touchscreens and tactile displays. For these applications, tactile sensations are produced by the application of a voltage to the conductive layer of an insulated haptic device such as a touchscreen, inducing electroadhesive forces between the device and the approached user finger.…”

“…For these applications, tactile sensations are produced by the application of a voltage to the conductive layer of an insulated haptic device such as a touchscreen, inducing electroadhesive forces between the device and the approached user finger. If the applied electric voltage is modulated in time the friction force acting on the finger will generate sensorial experiences [4][5][6][7].…”

Effect of Remote Masking on Detection of Electrovibration

“…Different tactile masking types are usually defined based on their temporal order (see Vardar et al [4]). As one of the most frequently applied techniques, forward masking has been shown to increase detection level for both low and high frequency stimuli, and can be used to selectively mask psychophysical channels [5], [6], [7], [8].…”

“…Considering that the interaction area of a touch screen is much larger than that used in earlier vibrotactile studies, tactile masking has great potential for the latest techonological applications utilizing electrovibration. So far, only two research studies have been conducted to investigate tactile masking on touch screens actuated by electrovibration [4], [21]. One was on the effect of local masking on perception of electrovibration, with masking stimuli also presented as electrovibration [4].…”