Tactile and Multisensory Perception of Low-Level Spatial Features: Investigating the Effects of Crossmodal Interaction and Temporal Context

Abstract

Low-level surface features, such as orientation and spatial frequency, are critical for both somatosensory and visual perception. These features are extracted early in cortical processing and serve as the foundation for higher-order processing in both modalities. While traditional sensory research often focuses on unisensory perception and isolated trials, accumulating evidence highlights the important roles of multisensory and temporal context, challenging the validity of such approaches. This thesis investigates how crossmodal influences and perceptual history affect tactile perception of low-level spatial features. In Chapter 3, the characteristics of orientation perception in the somatosensory domain are examined, establishing a tactile oblique effect independent of exploration method (active vs passive) and demonstrating a parallel serial dependence effect. Chapter 4 explores the crossmodal transfer of orientation adaptation using a modified tilt aftereffect paradigm, revealing an asymmetrical crossmodal adaptation effect (tactile adaptation elicits a visual tilt aftereffect) and asymmetrical intramodal serial dependence effect. Chapter 5 investigates crossmodal integration of spatial frequency between vision and touch in virtual reality and shows a statistical optimal integration that is unaffected by spatial proximity between stimuli in different modalities. Together, these findings reveal a complex crossmodal interplay between vision and somatosensation in the perception of low-level spatial features and highlight the intertwined effects of temporal context (as revealed by serial dependence and adpataion effect). Collectively, these findings underscore the need for an integrative and holistic approach in perception research.