Monday, March 19, 2012

How ‘Hugo’ Gave One Neuroscientist the Gift of Stereo-Vision

I’d like to share with my readers an email forwarded to me from Dr. Sue Barry. Dr. Bruce Bridgeman is a fellow neuroscientist who, like Dr. Barry had lived with a type of strabismus commonly called walleyes where the eyes point outward rather than inward.  Dr. Bridgeman wrote the email to Dr. Oliver Sacks, one of the most inspiring neuroscientists in contemporary literature. I decided to post this as a follow-up to “People Who Hate 3D Movies Should Get Their Eyes Examined” because Dr. Bridgeman’s revelation of stereovision happened while watching Hugo. I believe it was the way Martin Scorsese masterfully pushed the stereo envelope that gave him his first sense of volume and depth in the world. The last sentence in Dr. Bridgman’s email summarizing his new found stereo vision once again points to the immense value of immersive 3D in feature films,  “I feel myself to be in the visual world, rather than at it.” 

Email From Dr. Sue Barry 

Dear Barry,

Below is the complete text of an email that Dr. Bruce Bridgeman, a professor at UC Santa Cruz, wrote to Oliver Sacks regarding stereovision. As you'll see, Hugo had a profound impact on his vision.

All the best,

Email From Dr. Bruce Bridgeman to Dr. Oliver Sacks (published with permission from Dr. Bridgeman)

Dear Dr. Sacks,

I'm a neuroscientist who recently had restored stereopsis similar to that of 'Stereo Sue' in 'The Mind's Eye', but with experience rather than professional intervention. My case combined with Stereo Sue's makes me think that therapy for stereo-blindness, perhaps beginning with amplified disparity in natural scenes, should be part of every optometrist's toolkit. I teach the behavioral neuroscience course at UC Santa Cruz; my website below will tell you more than you ever will want to know about my career.

I have had flat fusion since my first corrective lenses at age 21, when my congenital exotropia (walleye) was corrected without prisms.  Here is a brief piece about my recent experiences. You can call me 'Binocular Bruce'.

There is a paper on my previous condition:

Schor, C., Bridgeman, B., and Tyler, C.W., Spatial Characteristics of Static and Dynamic Stereo Acuity in Strabismus. Investigative Ophthalmology and Visual Science, 1983, 24, 1572-1579.

Dr. Bruce Bridgeman’s Account Of His Experience With Hugo

In Mid-February 2012 I saw the movie ‘Hugo’ in 3D. Going into the theater my wife and I paid a surcharge for 3D glasses, which I thought were a waste of money for me – having been exotropic since childhood, I was nearly stereo-blind. But I took the polarizing glasses to avoid seeing annoying fringes in the film. To my great surprise, I immediately experienced the film in vivid stereo. I was enthralled. But perhaps the filmmakers exaggerated the stereo disparities in the film to enhance the value of the 3D technology. I still don’t know whether that’s true. I could find only qualitative estimates of the disparities used in the movie; perhaps the filmmakers thought only in relative terms. Hugo’s VFX supervisor Ben Grossmann said “We checked and checked: We were four to six times bigger than any other 3D movie. But everything looked amazing.”

I had to concentrate to appreciate the stereo effects, and purposely-blurred objects in the foreground bothered me – they captured my attention even though the filmmakers clearly wanted me to attend elsewhere.

When the movie ended we turned in our polarized glasses and walked out into the street. I was astonished to see a lamppost standing out from the background. Trees, cars, even people were in relief more vivid than I had ever experienced. Clearly the disparities weren’t amped up on the street. Did a few hours of enhanced disparity wake up long-neglected binocular neurons in my visual cortex?

There was also an effect on memory; I recall vividly what the street looked liked that night, though I don’t particularly recall the appearance of streets after exiting other movies before or since.

In the next few days (after seeing ‘Hugo’) I began examining the world in a new light. I also enjoyed using binoculars that also magnify disparities, now with 3 modes of vision, left eye, right eye, and stereo; previously I would look through only one side or the other, not needing to close the other eye to suppress the image. Riding to work on my bike I looked into a forest beside the road and saw a riot of depth, every tree standing out from all the others, a 3D feast. At first the best stereo effects were limited to stationary or slowly moving objects, but now a month later I appreciate stereo even as it enhances parallax.

In the ensuing weeks I enjoyed new stereo experiences every day. Trees in the view from our living room previously were just a panel of green, but now were separate objects jumping out at me. On March 7th, a windy day, I saw wind-whipped waves of grass in our back yard. It gave a whole new meaning to ‘amber waves of grain’. In dull spots during meetings or talks I can sit back and enjoy the stereopsis.

Entering awe-inspiring European cathedrals I always had to keep moving, sometimes to the annoyance of my companions, to appreciate the dimensionality of the space from parallax alone; I suspect that I could now experience them even better from stereo disparity alone. A year ago Dr. Suzanne McKee gave a masterful talk on stereopsis at our department; I objected that parallax could provide the same information, but she informed me that stereopsis provides finer-grained stereoscopic information than motion parallax, at lower thresholds. That took me aback, as I had thought and taught for years that the two sources of 3D information should be equivalent, one successive and the other simultaneous.

I remember only one stereo experience from my childhood. The back of a cereal box had little cutouts that could be bent forward to stand up when the background cardboard was lying on the kitchen table. Stooping down to put the figures at eye level, I saw them pop out. The disparities must have been enormous, and of course the 3D effect was hyped on the cereal box. I must have been seven or eight at the time. I have had exotropia and alternating strabismus since childhood. At the age of eight I was examined at the Wills Eye Hospital in Philadelphia, where the ophthalmologist recommended against surgery. No treatment was started, but we were poor and may not have been able to afford it. I remained misaligned until I was worked up at the Palo Alto Medical Clinic in 1968, having obtained health insurance as a Stanford graduate student. The optometrist discovered a large horizontal disparity, more than 20 diopters, and a small vertical one. I got my first corrective lenses and did orthoptic exercises such as pencil pushups etc. My eyes became aligned most of the time, but the effect seemed mostly cosmetic.

I have always had the ability to look through either my left or my right eye at will – it’s like a saccadic eye movement, except that it’s my end of the line of sight that moves rather than the far end. I had the habit of doing near tasks with one eye and far tasks with the other. After getting a spherical correction that gave me good focus simultaneously in both eyes I was able to fuse binocularly if I concentrated and if targets weren’t too close, but I got no benefit from it so I didn’t do it much.

Something is also lost with stereopsis. Previously I had a vivid perception of juxtaposition of objects, sometimes seeing amusing illusions where one object seemed attached to another. Now each object stands apart, no longer adjacent to more distant objects. But I feel myself to be in the visual world, rather than at it.


Bruce Bridgeman

Research Professor of Psychology
University of California, Santa Cruz
Dept. of Psychology
409 Social Sciences 2 Tel. (831) 459 4005
Santa Cruz, Ca. 95064 Fax (831) 459 3519

I wish to thank Dr. Sue Barry for bringing Dr. Bridgeman’s case to my attention and I wish to thank Dr. Bridgeman for permission to publish his letter to Dr. Oliver Sacks.

With over 100 scientific articles in peer-reviewed journals as well as several book chapters Dr. Bruce Bridgeman’s research centers on spatial orientation by vision and perception/action interactions.  His book, "Psychology and Evolution: The Origins of Mind" (Sage Press, 2003) explores the functions and neural basis of consciousness and theapplication of evolutionary theory to psychology. It introduces students to the emerging field of evolutionary psychology. Dr. Bridgeman applies concepts of evolutionary theory to basic psychological functions to derive new insights into the roots of human behavior and how that behavior may be viewed as adaptation to life’s significant challenges. Examining courtship, reproduction, child rearing, family relations, social interaction, and language development, Bridgeman uses evolutionary theory to help in the search to elucidate the foundations of human perceptions, experiences, and behaviors.