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Do 3D films make you dizzy 鈥� or is it just your imagination?

Dr Jenny Read writes about the effect 3D TV can have on a viewer in The Conversation.

The realism of today鈥檚 3D blockbusters can blow audiences away. By using 3D glasses to present different images to the two eyes, stereoscopic rather than a flat image on a screen. Now 3D televisions enable viewers to experience the effect at home as well.

Yet 3D has not become as popular as some might have hoped. Many people say watching 3D gives them unpleasant side-effects such as . Scientists don鈥檛 fully understand why this is. It鈥檚 true that . However, makers of 3D content are Basic_Principles_of_Stereoscopic_3D_v1 and work hard to avoid them.

A more fundamental problem may be conflict between different senses. When we watch a film such as , our visual system may tell us that we are wheeling high in the skies of a distant moon, but other senses tell us that we are sitting motionless in a chair. Of course, 2D films present this kind of conflict as well, but our brains may simply be more used to accepting that 2D content is not 鈥渞eal鈥�.

Some people have suggested that 3D content may cause more serious side effects. For example, 3D-tv-warning_en links its 3D TV set to a vast range of possible symptoms 鈥� not only headache, fatigue, motion sickness and eye strain, but also decreased postural stability, altered vision, dizziness, cramps, convulsions and even loss of awareness. Clearly if 3D TV has such effects, there are important safety implications. But to date, very little work has been done to assess this.

We recently , aged from 4 to 82 years, into my lab to watch the film on either a 2D or 3D TV. We used two common types of 3D TV, known as 鈥渁ctive鈥� and 鈥減assive鈥�. Participants carried out a battery of tests designed to assess their balance and coordination, both before and after viewing. They wore two triaxial accelerometers 鈥� small devices to record their body movements 鈥� as they walked around a simple obstacle course. To assess eye-hand coordination, participants played a 鈥渂uzz the wire鈥� game, guiding a hoop along a convoluted wire track without allowing the two to come into contact.

We argued that, if viewing 3D made participants dizzy, they would take longer to complete the obstacle course, and/or the accelerometers would show that their body movements were less stable. If it affected their vision, they would take longer to complete the 鈥渂uzz the wire鈥� game, and/or make more mistakes.

that adverse effects with 3D reflect underlying visual problems. So we also had our volunteers鈥� vision by eye care professionals before they visited the lab.

(Picture courtesy of Shutterstock)

On our objective tests of balance and coordination, we couldn鈥檛 detect any effects of 3D at all. Not surprisingly, people tended to perform a little better the second time round. But it didn鈥檛 seem to matter whether they had watched the film in 2D or 3D, or whether the 3D was active or passive. We also couldn鈥檛 find any links between age or eyesight and whether people were affected by 3D.

We did find that people who had viewed the 3D movie reported that the depth was . They also reported more , mainly headache and eye strain, but also including dizziness or nausea. However, it鈥檚 not clear that the dizziness was really due to 3D.

Craftily, we gave some of our volunteers 3D glasses, making them think they were viewing in 3D, but showed them the film in 2D. These people at about the same rate (3%) as those viewing real 3D. In contrast, people viewing real 3D were much more likely to report headache or eyestrain (around 10%) than people who just thought they were viewing 3D. This suggests that while 3D gives some people a headache, it doesn鈥檛 really make people dizzy 鈥� people just expect it to.

Of course, it鈥檚 possible that 3D caused an impairment that was so subtle or transient that our tests failed to detect it. On the other hand, that also implies less cause for concern in everyday life. We also tested only one 3D film, choosing Toy Story as something fun and engaging for all age-groups. Even if computer-generated 3D from the experts at Pixar doesn鈥檛 cause dizziness, it remains possible that less carefully-controlled 3D content 鈥� say, live-action football 鈥� could do so.

Nevertheless, given the lack of previous work in this area, our study provides welcome reassurance. Can 3D effects give you a headache? Yes, for some people. Can they make you dizzy? Probably not. Do they make Toy Story more exciting? That depends who鈥檚 watching.

is Reader in vision science at .

This article was originally published on . Read the .

published on: 29 July 2015