# The illusion of a “sense of body lightness” while walking: a preliminary exploratory study

## TL;DR

This study introduces a new illusion where people feel lighter while walking when given specific visual feedback, which could help in medicine and virtual reality.

## Contribution

The study introduces a novel illusion of body lightness during walking using subjectively preceding visual feedback.

## Key findings

- Nine out of 30 participants felt a sense of body lightness with subjectively preceding feedback.
- The illusion may be useful in medical rehabilitation and extended reality technologies.
- The illusion is generated by manipulating the timing of visual feedback during treadmill walking.

## Abstract

Illusions have historically been used in experimental psychology to reveal information about perceptual processes. A recent study reported that participants felt a sense of body heaviness when given slightly delayed (incongruent) visual feedback compared with the predicted somatosensory feedback. In this study, we reported a novel illusion of feeling a sense of body lightness while walking. There is consensus that an important factor in a body’s perceptual process is congruency between the senses. When our 30 participants experienced “subjectively preceding feedback” while walking on a treadmill, nine of them felt a sense of body lightness. In this report, we discussed how we were able to generate the subjectively preceding feedback, the mechanism that induces the illusion of a sense of body lightness, and the potential applications of this illusion. Although this study was just a preliminary and exploratory research, this new illusion has the potential to contribute not only to the medical and rehabilitation fields but also to extended reality technology and other interdisciplinary fields.