University of Toronto Study Finds Virtual Reality Distorts Body Perception

Body Size Perception and Virtual Reality Distortion

Researchers at the University of Toronto’s Faculty of Kinesiology & Physical Education (KPE) set out to test how accurately people judge their own body size relative to their surroundings in VR. Participants embodied a life-sized avatar to explore a virtual world built to match the scale of the real one, then were asked to estimate the minimum distance needed to clear a gap between two poles. The study found that participants predicted they would need a wider gap in VR than they did outside it. This phenomenon mirrors the experience of a giant navigating a small-scale world, a comparison drawn by the study’s authors to the protagonist of Gulliver’s Travels.

It was surprising to find how much larger people seemed to perceive their body in VR, says Xiaoye Michael Wang, a research associate at KPE who co-authored the study with professors Tim Welsh and Catherine Sabiston. People behaved as though their body had become larger relative to the world around them, even though nothing had actually changed in scale.

The study found that the distortion is not merely a transient effect of being inside the simulation. Notably, the researchers found that after taking their headsets off, participants still judged that they needed slightly wider openings in the physical world than they had before entering VR. The effect carried over after participants returned to the real world, suggesting that VR had temporarily recalibrated how they perceived the relationship between their body and surrounding space, Wang says.

Drivers of Perceptual Error

The research team identified two main explanations for these findings. First, because movement in VR was less precise, participants may have given themselves more room than necessary to pass through the opening without bumping into anything. Second, VR also changed visual perception itself: the opening appeared narrower than it was intended to be, which made people think they needed even more clearance.

This study adds to a broader body of work investigating human perception in immersive environments. Other researchers have aimed to reconcile conflicting findings regarding virtual hands and objects by using strict psychophysical methods. For instance, studies using consumer immersive VR devices have measured biases in size perception, often finding an underestimation of approximately 5% for virtual hands and objects. Analyses of reach-to-grasp movements in such environments have revealed longer movement times and larger maximum grip apertures (MGA) for virtual, as opposed to physical, environments. These findings confirm that human biases in the perception of size, distance, and shape of virtual objects remain a significant area of study.

Broader Scientific Context

Understanding these perceptual shifts is vital, as the scientific community continues to explore how anthropometric measurements and body size relate to various health outcomes in different contexts. While the KPE study focuses on the psychological recalibration of body schema in VR, other large-scale research, such as a retrospective cohort study of approximately 135,000 male construction workers, has examined how objective physical metrics like height, weight, and BMI are associated with long-term health risks like prostate cancer. These diverse studies highlight that whether in the physical world or a virtual simulation, body size remains a fundamental component of how individuals interact with and are affected by their environments.

Sources: Techxplore.