Small Study Suggests More Investigation Needed Into VR’s Effect On Kids

by Ian Hamilton • November 8th, 2017

An alarming headline in The Guardian popped up late last month: Virtual reality headsets could put children’s health at risk. After seeing that I reached out the researchers who conducted the original study and looked through a 40-page report I was provided explaining their methodology, which involved only 20 children. As the researchers note, “hardware manufacturers often advise that VR use is limited to children over 13 years old, but there appears to be no rationale behind the choice of 13 as a lower limit.”

“We restricted the sample of children to 20 as a precaution,” the report reads. “We were unsure of the effects of VR and saw this study as preliminary, with a view to expanding once results were known.”

The small study performed three tests before and after kids aged 8-12 spent 20 minutes wearing a VR headset. The three tests were eyesight, stereoacuity (depth perception) and balance. Researchers found no difference in eyesight and in both the stereoacuity and balance tests most children experienced no changes. In the stereoacuity examination, however, two children experienced a worsening effect in their test performed after wearing a VR headset.

In the balance test, one child “showed a dramatic decrease in postural stability” following VR use.

Under a summary header the report suggests “these findings present a starting point for investigations into health and safety issues related to VR.” That’s a much less eye-catching headline than the one The Guardian used.

“Overall, every child who took part in the study loved the VR experience,” another section of the report reads.

One thing I found interesting is the nature of the stereoacuity test researchers used:

“The test involved asking children to determine which direction a pac-man shaped character was facing whilst viewing a pair of stereo images comprised of random dots. These images were designed so that, when viewed using 3D (red and cyan anaglyph) glasses, the silhouette of the pac-man character would leap-out in front of the display (as a result of binocular disparities). Following each correct response, the task increased in difficulty (it became harder to detect the character as the disparities became smaller) and the point at which a child could no longer make out the character’s orientation provided an index of their stereoacuity (with lower scores indicating better performance). This test has previously been shown to have discriminative power and strongly correlates with the gold-standard TNO stereo test. Sixteen of the twenty children could see the character without any problems pre VR play. Fifteen had the same score post VR, and one participant’s score worsened. From the remaining four participants, one child was was unable to perform the assessment on both attempts – indicative of impaired stereoacuity in that child. Two remained stable, and one had a steep drop off in their stereo sensitivity- from being able to discriminate the orientation of the object with relative small binocular disparities, to only just managing to make out the pac-man shape in the easiest conditions.”

It seems odd they would use an old method of simulating a 3D visual effect (red and cyan glasses) as a way of examining the effect of a VR headset, and I’ve reached out to the researchers to find out more detail. Update: Professor Mark Mon-Williams at the University of Leeds, Specialist advisor to the health and safety phase of the VR study, offered more detail in an email regarding their stereoacuity test:

It was conducted under more controlled conditions (e.g. lighting, distance) than in a standard ophthalmology clinic – but is basically the gold standard assessment technique.

There are two important points. First, a child’s stereoacuity should remain stable, Second, good binocular function is required if a child is to enjoy good levels of stereoscopic vision.

In the small study described within the report, the important point is that the SAME assessment was carried out before and after the VR exposure. The expectation is that the same levels of stereoscopic vision should be measured before and after.

The fact that the levels changed indicates that the binocular system was placed under some stress. In this regard, the stereoacuity measure is a proxy measure of whether the visual system was affected by the VR exposure.

The way that the assessment system presents the stereoscopic images is not a factor when using this measure to detect change before and after exposure.

An example of the red/cyan 3D glasses referenced in the report.

From the report:

“Whilst it is difficult to draw broad conclusions from these tests, the results suggest that for the majority of children, one 20 minute VR game play will have little impact on their stereoacuity in the short-term. These data also indicate that, for a very small population of children, VR use may disrupt normal binocular coordination. These data make sense in the context of a relatively small number of children having less stable binocular vision, and it is this population that might be expected to be affected adversely through use of VR (at least in the short term – the long term consequences have not been established). The characteristics of children who might be most prone to disruption of binocular vision are currently unknown. We also do not know how long any disruption persists, nor the consequences of repeated exposure over a longer time frame. Further research into these potential factors is planned.”

This is obviously an important subject to the many parents out there (myself among them) who have children begging to play games like Job Simulator. The report suggests the following guideline for parents:

Restrict use to children with no history of ophthalmological problems

“You will note that this pilot study included a relative small number of participants and that the evidence is not conclusive (in either direction). Nevertheless, we believe it is incumbent on the VR industry to address this topic and several larger scale experiments are required to provide a comprehensive examination of the questions raised in this study,” University of Leeds researcher Dr. Faisal Mushtaq wrote in an email, adding they are also “extremely excited about all the possibilities that VR has for improving health.”

I will update this post if I hear more from the researchers, and of course I will follow this subject closely going forward. You can check out the full report here.

Update: Information added from an email received from one of the researchers and a paragraph was removed about a hypothetical test.

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What's your reaction?
  • Sven

    I would say VR gives a good counterpoint to always staring at close range screens like tablets, handhelds and phones. Give the eyes some time to relax and focus on infinity.

    The methodology is indeed laughable. The only concern would be VR untraining or undermining the vergence accommodation relation your brain is used to. You can’t test that by using the same flawed stereoscopic method. The only way is to check how long it takes to switch between focusing on something that is near and far. You could set up displays at varying distances from the test subject and see how long it takes them to identify a series of letters appearing on the screens.

  • Stranger On The Road

    I wonder if the child that had a worsen results was suffering from motion sickness or not. The 1st time I tried VR I did have a small case of motion sickness, but since than I have gotten used to it.

    any way, wasn’t the age 13 chosen because doctors said that at that point the eyes of the child have stabilized, or something along those lines. At an age younger than that, the eyes are still developing and the use of VR is feared to interfere with that development.

    P.S. a link to the study (if published) would have been appreciated, or at the very least its name so that we can look it up. Reading the biased bits of a lengthy paper is not my thing.

    • Ian Hamilton

      Looks like it is available here:

      • Stranger On The Road

        Thank you for the link, it is most appreciated.

  • bschuler

    I am so torn on VR for my nephews X-mas. I still remember growing up with PC games will make kids murders, monitors will give you cancer, etc.. fake scares.. but now with the shoe on the other foot, I am very afraid of throwing caution to the wind. Wish a real test could be done to ease people like myself’s fears. With VR becoming so common, where are all the massive government tests?

  • Ryan

    What headset where they using? Could have been cardboard.

    • Stranger On The Road

      16 used Vive and OR, while 4 used Google Cardboard. The child referenced is in the group that used the high-end HMD. (Pages 21-23)

  • Stranger On The Road

    What I found surprising in the study is that in the balance test, one of the children had improved balance after using VR! While another had a worsen balance and even fell during the test, I wish that the report indicated whether this is the same child with the worsen stereo acuity. Since this would mean that the child was suffering from motion sickness; which affects adults in VR as well.

    I don’t know if any of the researches would be reading this, but if anyone of them is. Then a clear indication between the lose of balance and worsen stereo acuity should be included since it might indicate that the child is suffering from motion sickness. And a nice test to try after that is to see if the motion sickness solutions (such as sea bands) could help that child or not.

    P.S. Page 10: What sorts of experiences would you like to have in virtual reality? in the US it is going to a fantasy world, in the UK it is going to a theme park….. the UK’s main wish…how sad is that!

    • Jurgen Hierck

      Depends on how you perceive it. Perhaps UK children don’t feel a need for escapism as much but just want a theme park more readily available;)

  • Jurgen Hierck

    Thanks for the article. Much appreciated. Being a parent myself it’s good to take notice of these kind of studies.

  • John

    I am a post grad researcher myself. The child’s stereo vision was effected for a short time after leaving VR. That suggests after leaving VR they needed to adjust BACK to normal vision. This suggests when the went into VR, they needed to adjust TO VR. The answer may lie with IPD.

    Which VR system did they use and is the IPD set up for each child? I have an IPD of 57. This is quite unusual for an adult and I find I am below the minimum IPD for my Vive, or an Rift. They could not have used these without the children (with smaller IPDs) needing time to let their eyes adjust to an unnatural IPD. If it was another system I am not surprised it needed time to adjust. I hope future HMDs, or those aimed at children with have much wider ranges which could minimise strain like this.

    One last point. All academics worth their salt are angling for more funding to further their research. This is just how academia works. This is a worthy topic, we should just keep that in mind. The reason this has not been done before is because it has been hard to convince backers to fund this kind of research without a commercial case.

  • Yeah, you wrote a great article. I shared the original article and got almost lynched by the VR community because it was too biased. But the study remains interesting.