Applying a novel visual-to-touch sensory substitution for studying tactile reference frames

Or Yizhar,Galit Buchs,Amir Amedi,Doron Friedman,Benedetta Heimler

doi:10.1038/s41598-021-90132-7

Or Yizhar, Galit Buchs + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-90132-7

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Abstract

Perceiving the spatial location and physical dimensions of touched objects is crucial for goal-directed actions. To achieve this, our brain transforms skin-based coordinates into a reference frame by integrating visual and posture information. In the current study, we examine the role of posture in mapping tactile sensations to a visual image. We developed a new visual-to-touch sensory substitution device that transforms images into a sequence of vibrations on the arm. 52 blindfolded participants performed spatial recognition tasks in three different arm postures and had to switch postures between trial blocks. As participants were not told which side of the device is down and which is up, they could choose how to map its vertical axis in their responses. Contrary to previous findings, we show that new proprioceptive inputs can be overridden in mapping tactile sensations. We discuss the results within the context of the spatial task and the various sensory contributions to the process.

Highlights

Perceiving the spatial location and physical dimensions of touched objects is crucial for goal-directed actions
The current study investigated the role of proprioception mapping tactile sensations to a visual image by measuring the effects of posture on reference frame selection
With the use of a visual-to-tactile Sensory Substitution Device (SSD), we asked participants to map vibrotactile stimulations delivered on their arms to a visual image and report its spatial location or orientation

Summary

Methods

For each white-colored pixel detected in a column, an actuator simultaneously vibrates on the inner arm This procedure results in the image’s Y-axis represented by the spatial location on the arm, and the X-axis represented by timing (e.g., the participant senses first the left part of the image). We investigated the properties of reference frame preferences when relying solely on proprioceptive cues To this aim, we used a visual-to-tactile SSD that transforms 2D black and white images into a series of vibrations delivered on the inner arm. We presented participants with an image of a line (Fig. 1b) and asked them to report on the line’s spatial location or orientation (towards the upper/lower bound of the picture), focusing on the perceived vertical axis of the stimuli. We did not exclude participants nor samples from the study

Results

Gravitational 3 Arm-centered

Discussion