Stanford Study Highlights Potential Negative Effects of Passthrough Headsets

Researchers at Stanford warn that headsets block out natural light and use cameras to create passthrough images of the world around you, which could have a negative psychological effect. 

Passthrough technology is fundamental in mixed reality and spatial computing. Sensors on headsets take in information from the surrounding environment. This digital reconstruction is displayed on opaque displays. Augmented reality elements can be added, and the images manipulated. 

However, the Stanford field study suggests that technology like the Meta Quest 3 and Apple Vision Pro may impact a user’s mental well-being in the long term. Now, scientists suggest we need further research into the potential downsides of mixed reality. 

What are these long-term effects, and what does this mean for the future of metaverse and spatial computing? Find out more about this new research here. 

The Benefits and Downsides of Passthrough

Passthrough is becoming a standard feature in headsets as we move toward increased spatial computing usage. Although it’s been around for a few years, the current market leaders include passthrough, and developers are innovating heavily around this feature. 

Passthrough isn’t the only way to achieve the result it does. Optical headsets like Magic Leap and Hololens use transparent displays that let you see the world around you while projecting digital additions through the glass and into your eyes. 

Headsets with passthrough improve on optical headsets. Optical headsets have a limited field of view, while passthrough headsets like the Quest 3 and Vision Pro offer nearly double this. 

The Stanford study says the optical headset field of view is “akin to holding a piece of printer paper horizontally at arm’s length and viewing the virtual layer of the world only through that small window.” 

That said, there are downsides to passthrough. Seeing the world through a live video means you lose focal depth, detail, and a lot of colour. 

At the moment, headsets with passthrough are also bigger and heavier. This means wearing headsets for long periods of time can become uncomfortable, making them impractical for the kind of tasks envisioned in the future of spatial computing. But this will all change as tech companies develop lighter hardware. When this happens, it’s likely that we’ll spend more time wearing these headsets. 

And this is where Stanford’s research comes in. What will it be like for headset users locked into a mixed-reality world for hours at a time?

“Seeing the World through Digital Prisms: Psychological Implications of Passthrough Video Usage in Mixed Reality”

This is the title of the recent research that has been conducted at Stanford’s Virtual Human Interaction Lab (VHIL). The team at VHIL has been working with virtual reality since 2003. Their studies explore VR’s effects on humans, and the VHIL is the top lab working in this area of research. 

A team of 11 researchers has authored the study that evaluates the use of  “headsets that block out light from the real world and instead rely on passthrough video as an enabling technology for mixed reality,”

While conducting the research, each researcher wore headsets with passthrough for several hours. The headsets were worn in public and private spaces, and the field study documents each user’s experiences. The study also analysed previous explorations on the psychological effects of passthrough. 

Due to the fact that Apple has only recently released the Vision Pro, this was not used in the field study. 

What Negative Effects Did the Study Highlight?

The study found passthrough technology to be impressive and noted that it has a range of uses. But it also highlighted the fact that it may have negative effects, and the researchers called for caution surrounding the use of the technology. 

The study authors stated: “We recommend caution and restraint for companies lobbying for daily use of these headsets and urge scholars to rigorously and longitudinally study this phenomenon.” 

The areas of concern were simulator sickness, visual aftereffects, distance judgment issues, and social absences. 

Judging Distances

Although the studies indicated that users found difficulty catching balls or picking up jigsaw pieces while using passthrough, the real problems were experienced “when trying to understand the position of moving people, such as navigating through crowds.”

Other issues faced while using the passthrough included pressing the elevator buttons and eating. 

Simulator Sickness

Passthrough users experienced a range of simulator sickness-related problems during the studies. These included nausea, eye strain, dizziness, headaches, and sweating. 

Factors that affected this included the user’s gender and age, content duration and locomotion type, and the headset resolution, latency and field of view. The study also found that short exposure to the same app over two separate days reduced the sickness by up to 40% over time. 

Distortion and Visual After Effects

The researchers note that although video distortion is rare, it does happen, and stationary objects often appear to move or stretch by 15% when a user turns their head. 

When dealing with moving objects, such as passing bicycles, these could sometimes disappear and reappear elsewhere in view. 

The movement of objects becomes particularly problematic when the user is concentrating on a task like drawing, as the images they create can become distorted. 

The studies showed that many of the difficulties a user faces in processing visual information carry on after the headset is removed, leading to “after effects”. 

How Does Passthrough Impact Social Behaviour?

With “social absence” highlighted as an adverse effect of using passthrough devices, you may wonder what this means. 

The VHIL team say that users will feel disconnected socially from anyone who is physically in the same space. The researchers state, “Based on past research as well as our field notes, one should not assume
that the social presence of other people beamed in via passthrough is equivalent to face-to-face

A Warning From Researchers

This isn’t the first study into the use of headsets. Previous studies have indicated that there are consequences to using headsets long-term. Until now, there hasn’t been specific research into passthrough video and how it will affect children. 

Based on the study’s findings, the researchers recommend that guidelines be implemented to restrict headset use. But as with previous warnings around the use of technology such as smartphones, when the technology and content are available, very few people will heed the advice. 

Last week saw the launch of the Apple Vision Pro with its best-in-class passthrough. But despite the improvement it offers compared with rival devices, the Vision Pro has a long way to go. The Verge editor-in-chief, Nilay Patel, was critical of Apple’s passthrough efforts, suggesting that it may be a “technological dead end” because it may never compare to natural vision. The Verge review also went on to highlight the fact that the EyeSight display doesn’t allow for genuine eye contact. 

But passthrough is an emerging technology. As with every aspect of mixed reality headset design, it will evolve to improve user experience. After all, Meta and Apple want us to spend more time wearing their devices, which won’t happen if users have a negative experience. 

You can read the full VHIL study here.

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