Fiche individuelle

Synchronization of audio-tactile stimuli represents a key feature of multisensory interactions. However, information on stimuli synchronization remains scarce, especially with virtual buttons. This work used a click sensation produced with traveling waves and auditory stimulus (a bip-like sound) related to a virtual click for a psychological experiment. Participants accomplish a click gesture and judge if the two stimuli were synchronous or asynchronous. Delay injection was performed on the audio (haptic first) or the click (audio first). In both sessions, one stimulus follows the other with a delay ranging from 0−700ms . We use weighted and transformed 3-up/1-down staircase procedures to estimate people's sensitivity. We found a threshold of 179ms and 451ms for the auditory first and haptic first conditions, respectively. Statistical analysis revealed a significant effect between the two stimuli' order for threshold. Participants' acceptable asynchrony decreased when the delay was on the haptic rather than on the audio. This effect could be due to the natural experience in which the stimuli tend to be first tactile and then sonorous rather than the other way around. Our findings will help designers to create multimodal virtual buttons by managing audio-tactile temporal synchronization.

La recherche a montré que l’interaction avec les surfaces peut bénéficier de l’ajout de retour haptique. La perception de cette retour haptique est influencée par d’autres modalités, telles que visuelles et auditives, ce qui permet de le renforcer ou de l’enrichir. Cependant, l’effet des textures 3D dans la réalité augmentée (AR), comme le rendu stéréoscopique et la déformation de surface, sur la perception tactile des textures n’a pas encore été étudié, en particulier dans une condition tactile active. Dans cet article, nous étudions l’interaction perceptuelle entre la stéréoscopie, la déformation de surface et la retour haptique dans un état actif. La retour haptique a été mise en oeuvre en utilisant une modulation par friction basée sur des vibrations à ultrasons, tandis que la retour visuelle a été implémentée avec une paire de lunettes 3D en AR. L’étude expérimentale est une exploration visuelle-tactile d’une texture virtuelle. Notre objectif est de comprendre l’interaction d’une modalité sur l’autre pour la rugosité et la perception de la profondeur. Nous avons demandé aux participants de porter des jugements de rugosité de texture visuelle et tactile et d’estimer la profondeur de la déformation de la texture sous leurs doigts. Nos résultats suggèrent que : 1) la rugosité tactile perçue peut être modifiée en ajoutant un rendu stéréoscopique et / ou une déformation de surface visuelle mais uniquement pour les textures tactiles lisses. 2) La rugosité visuelle perçue peut être modifiée en augmentant la rugosité tactile. 3) La rugosité globale (visuel + tactile) est principalement impactée par la perception tactile.

Active touch (AT) is defined as the action of touching, implying voluntary, self-generated movement. While much research has been conducted on multisensory interactions in passive touch, research on how AT influences how the senses interact remains scarce. Using a haptic surface (HS) based on ultrasonic vibrations, we investigated the perception of synchronization of audio-tactile stimuli in AT. Tactile stimuli were delivered upon sliding the finger over the tactile zone of the HS. Auditory stimuli (a white noise burst) followed the tactile stimuli with a delay ranging from 0 to 700 ms. Participants reported whether the two stimuli were perceived as coinciding in time or not. Two conditions were employed for the discrimination task: (i) either with a visual clue showing the location of the tactile zone on the screen; (ii) or with a black screen below the HS. Time delays (ms) between the tactile-auditory inputs were converted in displacement (mm), depending on the sliding velocity of the participant’s finger across the HS, to calculate spatial distances at which the two stimuli were perceived as coinciding or not with the same probability. The average distance was 5.87mm with visual cues and 5.63mm without a visual cue. No significant difference was found between the two visual conditions suggesting performance is not affected by the presence of a visual cue regarding the location of the tactile stimulus. Our results provide insights into the sensitivity of participants in perceiving spatiotemporal differences between tactileauditory stimuli generated during AT exploration.