Understanding the interplay between surface roughness and material elasticity in haptic texture perception is important. In the real world, these characteristics do not occur isolated from one another, yet, the haptic perceptions of surface features and material properties are often investigated individually. This highlights the need for suitable stimulus material for haptic perceptual experiments. The present research details the manufacturing and validation of a database of stochastically-rough, elastic stimuli tailored for haptic perceptual experiments. The stimulus set comprises 49 3D-printed samples, offering a systematic variation in stochastic microscale roughness and material elasticity, replicating natural surface features without compromising experimental control. The surfaces were generated using an algorithm that produces randomly rough surfaces with well-defined spectral distributions, demonstrating fractal properties over a large range of length scales. Controlled variations in elasticity were implemented via variations of the printing material composition. Finally, we present preliminary perceptual data from two observers, illustrating the discriminability of the stimulus space for roughness and softness discrimination. This database aims to facilitate haptic research on material and texture perception, offering a controlled yet naturalistic set of stimuli to explore the intricate interplay between surface roughness and material elasticity in shaping haptic texture perception.@en

Temporal binding refers to a systemic bias in the perceived time interval between two related events, most frequently voluntary motor actions and a subsequent sensory effect. An inevitable component of most instrumental motor actions is tactile feedback. Yet, the role of tactile feedback within this phenomenon remains largely unexplored. Here, we used local anesthesia of the index finger to temporarily inhibit incoming sensory input from the finger itself, while participants performed an interval-estimation task in which they estimated the delay between a voluntary motor action (button press) and a second sensory event (click sound). Results were compared to a control condition with intact sensation. While clear binding was present in both conditions, the effect was significantly enhanced when tactile feedback was temporarily removed via local anesthesia. The results are discussed in light of current debates surrounding the underlying mechanisms and function of this temporal bias.

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Recent studies, [1, 2], suggest that the mechanics of fingertip-object interactions can provide insight into the functional link between the hand, the brain, and our haptic perception of the world. When two convex objects, a finger′푓′and a surface′푠′, come into Hertzian contact, the respective elastic moduli퐸&, and 퐸', the radii of curvature, 푅&and 푅', the pressing force,푓, the deflection, 푑, and the size of the contact area, 푎, of these bodies are interrelated. If we assume that the finger and the surface are incompressible, and that the finger is a homogeneous, isotropic sphere, (its behaviour does not deviate much from that theory [3]), then it can be shown that 퐸'and 푅'play interchangeable roles in the relationship that link 푎to 푓. If 푎is an adequate representation of the mechanical state of the finger, then two behavioural hypotheses follow, namely:There exists perceptual metamers of compliance, i.e, physically distinct stimuli give rise to the same perception becauseRsandEsare confounds.An object's surface curvature and compliance are increasingly confused with increasedEs.Our findings suggest that, indeed, the interaction between a fingertip and a convex surface produces a perceptual outcome equivalent to decreasing 퐸', while the interaction between the fingertip and a concave surface creates a perceptual estimate of surface compliance equivalent to an increase in 퐸'. A low or high 퐸'both yield a metameric response, however, as predicted, for low 퐸', the effect diminishes significantly. These results, for the first time, provide evidence of a tactile perceptual metamer that can be predicted basic mechanics. The implications of this finding for perceiving and rendering object properties are discussed with respect to the functional link between the hand, brain and environment. @en

This workshop aims to generate an interdisciplinary research agenda for digital touch communication that effectively integrates technological progress with robust investigations of the social nature and significance of digital touch. State-of-the-art touch-based technologies have the potential to supplement, extend or reconfigure how people communicate through reshaping existing touch practices and generating new capacities. Their possible impact on interpersonal intimacy, wellbeing, cultural norms, ways of knowing and power relations is far-reaching and under-researched. Few emerging devices and applications are embedded into everyday touch practices, limiting empirical exploration of the implications of digital touch technologies in everyday communication. There is, thus, a real need for methodological innovation and interdisciplinary collaboration to critically examine digital touch communication across social contexts and technological domains, to better understand the social consequences of how touch is digitally remediated. This agenda-setting workshop will bring together HCI researchers and designers with colleagues from sociology, media & communications, arts & design to address key research challenges and build the foundations for future collaborations.

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