Does temporal asynchrony affect multimodal curvature detection?

Multiple sensory modalities gather information about our surroundings to plan appropriate movements based on the properties of the environment and the objects within it. This study was designed to examine the sensitivity of visual and haptic information alone and together for detecting curvature. When both visual and haptic information were present, temporal delays in signal onset were used to determine the effect of asynchronous sensory information on the interference of vision on the haptic estimate of curvature. Even under the largest temporal delays where visual and haptic information were clearly disparate, the presentation of visual information influenced the haptic perception of curvature. The uncertainty associated with the unimodal vision condition was smaller than that in the unimodal haptic condition, regardless of whether the haptic information was procured actively or under robot assistance for curvature detection. When both visual and haptic information were available, the uncertainty was not reduced; it was equal to that of the unimodal haptic condition. The weighting of the visual and haptic information was highly variable across subjects with some subjects making judgments based largely on haptic information, while others tended to rely on visual information equally or to a larger extent than the haptic information.