Most of us have seen a movie that drastically altered our view of the world, but how many can say that a movie changed their vision? Bruce Bridgeman, a neuroscientist at the University of California, can! Growing up stereoblind, Bridgeman always saw the world as flat because he could not perceive depth-of-field. To him, trees in a forest looked like simple green panels, and he would have to reposition his head to figure out how close or far objects were. However, all that changed after a fateful visit to the cinemas. After watching the movie “Hugo” in 3D, Bridgeman was able to see depth for the first time in his life. The movie had essentially cured his condition permanently.
Because of a condition called “alternating exotropic strabismus” or “lazy eye,” Bridgeman could never look at an object or scene with both eyes at the same time, which caused stereoblindness or the inability to see depth.
From the Roman physician called Galen of Pergamon to Leonardo Da Vinci, scientists and experts have known for centuries that two eyes perceive images better than one. The image that we see with our left eye is slightly different from how we see the same image with our right eye. It was later discovered that the slight difference actually allows our brain to perceive depth-of-field.
However, Bridgeman had a condition known as “alternating exotropic strabismus,” which caused his eyes to drift outward. That means he could look at a particular scene with one eye at a time but never with both eyes at the same time. Because of this, his brain was unable to form stereovision, which is the ability to perceive depth. However, he used other clues such as motion parallax, occlusion, perspective, and shading to gather information about depth.
Those who are born with impaired stereovision come to rely on these alternative clues to perceive depth. That is why they often do not realize they have this condition until they are adults. Moreover, the standard vision tests that optometrists perform do not include stereovision, which leads to delayed diagnosis.
The movie Hugo came as a revelation for Bridgeman. From the moment he put on his 3D glasses, he noticed a stark difference in his vision. Even after the glasses came off, Bridgeman was able to see the world in 3D, which is something could never do before.
In February of 2012, the 67-year-old neuroscientist went to the theater with his wife to watch the Martin Scorsese movie called Hugo. Much like everyone else, he paid extra to get his 3D glasses. The moment he put on those glasses, he saw the scenery and the characters in the movie leap out. He had never experienced stereovision like this before. Surprisingly, the improved ability to perceive depth did not leave him even after he took off the glasses. Lampposts, trees, cars, and people looked more vivid than ever. Bridgeman was seeing the world in 3D for the first time ever!
As a neuroscientist, Bridgeman’s area of work was the visual system. Naturally, he began researching for a possible explanation for what had happened to him. Turns out, his case was exceptional, and watching a 3D movie may not be a cure for stereoblindness.
After researching the work of Torsten N. Wiesel and David H. Hubel’s with kittens, Bridgeman came up with some possible explanations. The 1981 Nobel Prize winners had extensively studied the visual systems of kittens with misaligned eyes. Their research showed that most of the cells in the visual cortex of the brain get activated by one of the eyes. However, a small percentage of these cells respond to both eyes. Bridgeman hypothesized that these analogous cells in his visual cortex must have been activated while watching the movie, and that allowed stereoscopic vision.
Other experts have stated that although the same strategy may not fully work for everyone, the movie might have had something to do with his improved vision. Several scientific studies have also shown that people can improve their stereo vision by training their eyes and changing their visual habits. A famous example of that is Sue Barry, also known as “Stereo Sue,” who is said to have experienced stereovision for the first time when undergoing vision therapy.
A few months after watching the movie, Bridgeman visited his optometrist, who conducted tests to gauge his stereo threshold. He had taken the same test decades earlier. However, this time, the results showed a dramatic improvement in his stereovision, though it was still not within the normal range. 1,2,3