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Crossing the arms impairs vibrotactile frequency perception by degrading sensory evidence: Evaluation with a Drift Diffusion Model.

Poster Session D - Monday, March 9, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Naoya Tachibana¹ (), Yuko Yotsumoto¹; ¹The University of Tokyo

The present study explores the interaction between egocentric and external reference frames in non-spatial processing, specifically vibrotactile frequency perception. While previous studies primarily investigated the impact of reference frames on spatial judgments, such as in temporal order judgment with arm crossing (Yamamoto & Kitazawa, 2001), their effects on non-spatial processing, including texture and frequency perception, have been largely unexplored. Tactile frequency perception is known to exhibit an assimilation effect, wherein perceived frequency shifts towards that of a distracting stimulus, even when individuals attempt to ignore it (Kahrimanovic et al., 2009; Kuroki et al., 2017). This effect is pronounced when stimuli are synchronized. Here, we investigated the combined influence of stimulus simultaneity and arm-crossing on tactile frequency perception. In the experiment, vibrotactile stimuli were presented to the left and right index fingers, and participants identified which finger received the higher frequency. Stimuli were delivered either sequentially or simultaneously, with arms either uncrossed or crossed. Behavioral results revealed that non-spatial vibrotactile frequency perception was impaired not only by the absence of simultaneity but also by arm-crossing. To examine the underlying decision-making process, we applied the Drift Diffusion Model (DDM) to response time and accuracy data. The modeling revealed that the drift rate—a parameter reflecting the quality of sensory evidence—was significantly reduced in the arm-crossed condition compared to the uncrossed condition. These results suggest that non-spatial tactile perception is influenced by spatial information, and that reference frames affect not only spatial localization but also early sensory evidence accumulation in non-spatial perceptual decisions.

Topic Area: PERCEPTION & ACTION: Other