Visuo-tactile integration in texture perception: A replication and extension study

Abstract

Employing a sensory conflict paradigm, previous research has found that vision and touch contribute, on average, equally to the visuo-tactile perception of surface texture. Our study aimed to, firstly, replicate the original findings using a comparable setup and stimulus set; secondly, examine whether equal modality contributions can also be observed on an individual basis (using a within-subject design); and thirdly, explore how visuo-tactile integration is affected by illumination angle (top vs. oblique). Participants explored a discrepant standard consisting of different abrasive papers by vision, touch, and using both modalities simultaneously, and subsequently had to find the closest visual, tactile, and visuo-tactile match from a set of matching stimuli. We replicated equal contribution from vision and touch across the whole sample in both illumination conditions. We also found considerable inter-individual variations in the modality contributions when the stimuli were illuminated from the top. Interestingly, this variation decreased under oblique illumination, with most participants showing an about-equal contribution from both modalities to the combined texture percept. These findings are consistent with the assumption that the perceived discrepancy between vision and touch was reduced under oblique illumination suggesting overall that visual and tactile information are only weighted equally within a certain range of experienced discrepancy. Outside this individual range, one of the modalities is weighted higher with no clear preference for either modality.

Crossmodal Texture Perception Is Illumination-Dependent

“…Our findings on crossmodal matching are also in line with a previous study from our group on bimodal visuo-tactile matching where we investigated the relative contributions of vision and touch to roughness perception (Kangur et al, 2022). In this study, we employed a discrepancy paradigm in which a smoother visual stimulus (150 grit) was always paired with a much rougher tactile stimulus (60 grit), and matches had to be selected uni-or bimodally.…”

“…Thus, lower grit values indicate rougher and higher grit values finer abrasive papers. We chose grid values based on previous research (Kangur et al, 2022;Lederman and Abbott, 1981), and pilot experiments to ensure stimuli were perceptually distinguishable and increased monotonically in perceived roughness. The setup used for stimulus presentation consisted of a black rectangular box (H: 60 cm, W: 73 cm, D: 30 cm) placed on a table with two openings: the upper one (W: 15 cm, H: 10 cm) for the visual and the lower one (W: 15 cm, H: 3 cm) for the tactile exploration of the stimuli (comparable setup to, Kangur et al, 2022;Lederman and Abbott, 1981).…”

“…We chose grid values based on previous research (Kangur et al, 2022;Lederman and Abbott, 1981), and pilot experiments to ensure stimuli were perceptually distinguishable and increased monotonically in perceived roughness. The setup used for stimulus presentation consisted of a black rectangular box (H: 60 cm, W: 73 cm, D: 30 cm) placed on a table with two openings: the upper one (W: 15 cm, H: 10 cm) for the visual and the lower one (W: 15 cm, H: 3 cm) for the tactile exploration of the stimuli (comparable setup to, Kangur et al, 2022;Lederman and Abbott, 1981). Two sandpapers (7.5 cm × 12.5 cm in size) of each grit value were affixed on a rotating table with a diameter of 60 cm which was placed inside the box just below the tactile exploration opening (see Fig.…”