Thursday, February 23, 2012

3D Movies and the Primal Brain

In my previous blog, Engaged in 2D and Immersed in 3D I pointed out that in a 2D movie, motion is perceived as changes in the up, down and sideways position of one object in relation to other 2D objects. We can perceive three dimensions in a 2D movie via single eye or monocular cues such as occlusion, motion, shading, size, parallax, texture gradient, perspective, saturation and brightness. However, lacking in a 2D movie is the most powerful 3D influence on the brain—disparity. Disparity is the term used to define the two slightly different perspectives of the world that we see due to the separation of our eyes and the distance between them. It’s this separation of our eyes and our ability to converge them toward an object that gives us a true sense of depth and volume. We all remember from biology that our eyes send this visual information along bundles of nerve fibers or pathways to our primary visual cortex. It’s now known that this visual information subsequently travels from the primary visual cortex to higher portions of the brain that are specifically tuned to the degree of disparity created within the visual fields of our two eyes. In this, the second in my series on the neuroscience of 3D, I will point out that there is likely even more going on in a 3D movie than what we consciously perceive.

Can We See Without Seeing?

Seems like an odd question but one that has been a major source of research and controversy within the field of neuroscience for many years. There is a condition described decades ago by Dr. Larry Weiskrantz that was given the oxymoron, “blindsight” in which patients with severe damage to their primary visual cortex can nonetheless “see” emotionally charged objects. While these patients claim they see nothing, they nonetheless exhibit physiological responses indicative of emotional recognition of the objects.

How Can Patients That Are Blind From Visual Cortex Damage See?

There are neuroscientists, including one of my professors, Dr. Michael Gazzaniga who claims that the phenomenon of blindsight is simply a matter of tiny islands of spared visual cortex that are no longer fully connected as they would be in the intact brain. Others postulate the more intriguing idea that there are visual pathways, separate from those projecting to the more commonly known parts of the brain that mediate a type of vision that falls below the radar of conscious visual perception. Whether blindsight is a real phenomenon or merely severely degraded normal vision, the search for an explanation of how the blind can “see” in the absence of their visual cortex has stimulated a great deal of research into the possible role that other, previously unknown visual pathways play in subconscious awareness. We now know that information from our two eyes traverses the brain along many different routes including pathways destined for the more primitive parts of the brain called the limbic system that mediate emotional responses evoked by threatening visual stimuli, often in the absence of conscious awareness.

How does this relate to 3D movies?

Let’s consider an effect sometimes used in 3D movies for its shock value that has been referred to as the “gimmick factor”. I think many of us can point to anecdotal experiences we’ve had in 3D movies where we’ve found ourselves reflexively ducking out of the way of an object rapidly accelerating and coming out of the screen toward us. Indeed, those who went to see Piranha experienced various body parts that seemingly flew out at them from the 3D screen and those who saw the 2009 release of The Final Destination 3D experienced other, more rigid objects that appeared to fly out of the screen, intruding on their personal space. I went to the later film for the purpose of studying my own reactions to shock 3D as well as that of the audience around me. 

In the formulaic premonition scene in The Final Destination there were several instances of objects flying out of the screen into the audience that were intended to create an emotionally charged startle response. In one case I had just enough time to focus my eyes on an object jettisoned a hundred feet up in the air, slowly reaching the apex of its trajectory before coming down, “smashing” into the theater, hitting an actress that appeared to be standing between me and the screen and landing “in my lap”. Even though my intention was to observe the movie objectively and analytically from a professional stereographic vantage point, I experienced an involuntary sense of heightened awareness and anticipation as the object reached the apex of its trajectory. Then in the blink of an eye, as the object dropped toward me, the disparity of the object crossed and widened, signaling to my brain that it was headed out of the screen, toward the girl in the movie and me. Literally before I had a chance to think, I found myself “instinctively” moving out of “harms way”. It was nothing I did consciously and I noticed other people in the audience reacting in the same manner.

Was I experiencing a type of blindsight?

Was I subconsciously sensing danger causing me to instinctively move away? David Ellis, the director of The Final Destination is a master of emotionally priming us with images that build tension and anticipation before hitting us almost instantaneously with extremely disturbing images that strike our retinas and literally shock our nervous system. The significance of 3D in facilitating my reaction was obvious to me after the fact. The added dimension provided precise information about where the object was in the air relative to my own body and the subsequent changes in dynamic disparity during the drop signaled the speed and direction of its path through the screen and into my personal space. I don’t believe there was sufficient time for me to consciously move out of the way, nor do I think I would have been motivated to move if I had been fully aware of what was happening.

Experiencing the film in 2D would have distanced me from the action.

As I reflected on the film, I wondered if I might have experienced similar reactions had I seen the movie for the first time in 2D. I believe there would have been a startle reaction in 2D but not as intense as the one I experienced in 3D and there is a very compelling reason why. In Engaged in 2D and Immersed in 3D I discussed that in our everyday lives we converge our eyes on objects that are in close proximity to us, creating two perspectives that are slightly offset horizontally because of the separation of our eyes. Our brain fuses the two perspectives into a single 3D image creating the impression of depth and volume. However, when objects are viewed at distances of several hundred yards, depth cues that we can detect with one eye such as relative movement of objects and occlusion (one thing passing in front of another) exist, but the horizontal offset of the images from our two eyes becomes less and less as the distance of the object from us increases. Because our eyes do not converge on objects in the distance, the resulting images falling on both retinas are precisely the same with no horizontal offset. This lack of disparity in the presence of monocular depth cues signals to the brain that objects are far away. 

In 2D movies our brain is constantly presented with a cue conflict in which objects on the screen that might normally be perceived as close to us, have no disparity. Consequently our brain interprets those objects and the entire 2D storytelling as taking place at a distance from us. Our attention in 2D movies is directed to the screen “over there”. This is in contrast to how we perceive a 3D movie where we experience full dynamic disparity that can evoke conscious and subconscious responses to objects appearing all around us as well as objects that appear deep behind the screen. Indeed, our attention during a 3D movie is influenced by the entire spatial expanse of the movie theater. As a consequence, dramatic emotional effects directed to the audience in a 3D movie become very personal to each audience member.

The high road and low road of vision

There are volumes of data in the scientific literature to support the notion that emotionally charged visual information, perhaps like the object I experienced in The Final Destination travels through the brain via several different pathways some of which do not include the primary visual cortex and conscious awareness.  One of these pathways - the Parvocellular Pathway - is metaphorically called the high road.  It sends data-rich visual information (color, texture, shape, etc.) that we perceive consciously about what something is to higher portions of the brain including the visual cortex. The other pathway - the Magnocellular Pathway – called the low road sends sparse visual information (i.e., edges, location, direction and speed) about where something is in spatial relation to our body to primal neural structures lying deep within the brain.  It is thought that this pathway often operates in the absence of consciousness.

To be effective in immediate danger situations the low road brain cells must carry critical information about the location of objects more rapidly than the high road that in turn sends more detailed information about what the object actually is. The information carried by the low-road traverses the brain faster because it filters out only mission critical survival information about location, direction and speed and also, the neurons that make up the low-road are heavily insulated by a fatty sheath that increases neuronal conduction times through the brain. In other words, information transmitted via the low road causes us to duck out of the way before we have time to consciously assess what it is we are moving away from. 

Disparity is a key element in low road activation and transmission

The above is admittedly a simplistic view of the way the brain handles instantaneous, emotionally packed visual information. In reality the brain is a complex matrix of neuronal activity constantly in flux and shifting in location, intensity and frequency depending on many things including attention, sensory input and motivational factors. To focus on one structure within the brain and point to how it functions in isolation from the rest of the brain is not particularly valid. However in an effort to better understand the brain and how it functions in relation to 3D movies it is reasonable to postulate from the scientific literature that a key to subconscious visual startle reactions is dynamic disparity, the most sensitive indicator of position in space, speed of movement and direction of movement. In analyzing reflexive emotional responses it would appear obvious that the number of way stations that visual information relevant to survival must pass through has to be limited and those structures that are involved initially should have influence that outweighs other ongoing priorities in brain activity.

We know that one of the first areas of the brain to receive low road information is the superior colliculus, lying deep within the brainstem.  This is an area that controls gaze and head turning and can subconsciously trigger rapid head and eye movement, forcing us to converge toward an immediate danger situation. Significantly, the majority of brain cells in the superior colliculus are specifically tuned to react to variations in the disparity coming from our two eyes.  In fact neurons have been described in the superior colliculus that respond selectively only to “near” objects and other neurons only to “far” objects.  It’s not likely that the disparity information reaching the superior colliculus results in the fusion of the two perspectives from our eyes into a 3D image.  Instead, I believe that the data received by disparity-tuned neurons in this brain structure is processed to determine relative distance, direction and speed in the absence of constructed 3D images.

These disparity sensitive neurons in the superior colliculus subsequently send processed disparity information directly to the amygdala in the limbic system as well as to other primitive brain structures that have been well established as modulating emotion. In extreme survival situations, the activated amygdala is known to trigger behavioral and autonomic responses (visceral responses below the level of consciousness) that evoke flight or fight reactions such as instantly ducking or moving out of harms way in response to threatening visual stimuli.


We know that our highly evolved frontal cortex mediates cognitive functions that normally inhibits or controls the amygdala and consequently evoked emotions.  I contend that our brain’s reaction to a 2D movie is more of a top down cognitive process involving the higher order frontal cortex.  The greater our suspension of disbelief, the more these higher cognitive functions come into play, releasing emotions mediated by the lower order amygdala.  On the other hand, in a 3D movie, emotionally packed visual information more directly affects these lower order emotional areas of the brain in a bottom up fashion, evoking a more primal subconscious response.

The description of my experience in the shock film The Final Destination is intended as an example of one end of a continuum of emotional and affective responses in the brain that are likely evoked during 3D movies; from the very subtle to the extreme. Indeed it’s likely that the subtle but effective single frame image of Brad Pitt appearing behind Ed Norton as his alter ego in Fight Club might have had a greater emotional impact had it been in 3D.  I believe the more extreme subliminal instances of Captain Howdy’s face in The Exorcist would have had an even greater effect in 3D, not only because of the underlying story but also because threatening faces and faces exhibiting extreme fear are some of the most effective emotional visual stimuli in humans.  On the other end of the spectrum, simply the timing and the framing of a 3D shot, the relationships of the characters in frame and the relative motion of the antagonist can create a greater degree of anticipation, anxiety and/or fear with the proper use of disparity.

All the parameters of binocular vision that we experience in the real world also exist in the 3D theater. At Legend3D, we apply many of the established neuroscience principles related to binocular vision and perception in our process of creating the most effective 3D to enhance the storytelling as well as in producing the most comfortable 3D to watch. I believe it will be found that the same binocular visual mechanisms that have served our species so well for hundreds of thousands of years are very much in play when we experience a 3D movie.  How disparity is choreographed in a 3D movie can enhance or detract from the overall experience. In the wrong hands 3D can be distracting and even quite painful, but in the right hands a great story, great characters and skillful direction coupled with the proper use of disparity will always enhance the storytelling.

(1)   Bacon, B.A., Villemagne, J., Bergeron, A., Lepore, F., Guillemot, J.P. Spatial Disparity Coding in the Superior Colliculus of the Cat. Experimental Brain Research 1998 119, 3, 333-44.
(2)   Campion, J., Latto, R. & Smith, Y. M. Is Blindsight an Effect of Scattered Light, Spared Cortex, and Near-threshold Vision? Behavioral and Brain Sciences 1983 6, 423-448.
(3)   de Gelder, B., Vroomen, J., Pourtois, G. & Weiskrantz, L. 1999. Non-conscious Recognition of Affect in the Absence of Striate Cortex. Neuroreport 10, 3759–3763.
(4)   Fendrich, R., Wessinger, C., Gazzaniga, M. Speculations on the Neural Basis of Islands of Blindsight. Elsevier. 2001, 134, 353-366.
(5) LeDoux, J. E. Brain Mechanisms of Emotion and Emotional Learning. Current Opinion in Neurobiology.  1992, 2, 191–197.
(6)   LeDoux, J. E. 1996.The Emotional Brain. Simon & Shuster, New York.
(7)   LeDoux, J.E. Emotion Circuits in the Brain. Annual Review of Neuroscience. 2000, 23, 155–184.
(8)   Liddell, B., Brown, K., Kemp, A., Barton, M., Das, P., Peduto, A.  Gordon, E. and Williams, L. 2005. A Direct Brainstem–Amygdala–Cortical “Alarm” System for Subliminal Signals of Fear.  NeuroImage 1999, 24, 235– 243.
(9)   Linke, R., De Lima A.D., Schwegler, H., Pape H.C.  Direct Synaptic Connections of Axons from Superior Colliculus with Identified Thalamo-Amygdaloid Projection Neurons in the Rat: Possible Substrates of a Subcortical Visual Pathway to the Amygdala. The Journal of Comparative Neurology. 1999 403, 2, 158–170.
(10) Mimeault, D., Paquet, V., Molotchnikoff, S., Lepore, F., Guillemot, J.P. Disparity Sensitivity in the Superior Colliculus of the Cat. Experimental Brain Research. 2004 1010, 1-2, 87-94
(11) Morris, J.S., Ohman, A., Dolan, R.J., A Subcortical Pathway to the Right Amygdala Mediating ‘Unseen’ Fear. Proceeding of the National Academy of Sciences of the United States of America. 1999 96, 1680–1685.
(12) Phelps, E. A. & LeDoux, J. E. Contributions of the amygdala to Emotion Processing: From Animal Models to Human Behavior. Neuron 2005 48, 175–187.
(13) Tamietto, M. and Gelder, B. 2010.Neural Bases of the Non-Conscious Perception of Emotional Signals. Nature Reviews Neuroscience. 11, 697-709
(14) Weiskrantz, L. 1986. Blindsight: A Case Study and Implications. Oxford: Oxford     University Press.
(15) Whalen, P. J. and Phelps, E. A. 2009. The Human Amygdala. Guilford Press.

I wish to acknowledge the review and suggestions of the following professionals:

David Loiselle, Ph.D. is Clinical Associate Professor of Neurology at the University of Rochester and Director of Intraoperative Neuro-monitoring at the University of Rochester Medical Center. Dr. David Loiselle is an internationally recognized clinical neurophysiologist. He was one of the first innovators and a leading proponent of interoperative electrophysiological monitoring to help reduce the risk to patients undergoing surgeries involving the nervous system. He was the first neurophysiologist to establish a curriculum for training medical residents and fellows in the clinical utilization of evoked potentials. Dr. Loiselle He is an active member of the American Academy of Neurology, American Clinical Neurophysiology Society, American Epilepsy Society, International Society of Intraoperative Neurophysiology, and the American Society of Neurophysiological Monitoring, where he is member of the Board of Directors. 

Scott Squires has a full range of experience working with both traditional and cutting edge digital techniques to create photo real visual effects. His career began with the development of the Cloud Tank Effect for Close Encounters of the Third Kind. Among the many feature films he has worked on, he received Oscar nominations for Best Achievement in Visual Effects for The Mask, Dragonheart and Star Wars: Episode 1 - The Phantom Menace. Scott is the recipient of a Scientific and Engineering Award from the Academy of Motion Picture Arts and Sciences for his pioneering work in the area of Film Input Scanning. He was co-founder of Dream Quest Images, a leading visual effects facility where he was Visual Effects Supervisor, as well as the company’s president for six years before the company was acquired by Disney Studios. From there he went to ILM where, where for 20 years he was its first CTO as well as visual effects supervisor and commercial director. Scott Squires is a member of the Academy of Motion Pictures Arts and Sciences - Visual Effects Branch. He is on the board of the Visual Effects Society, serves on the technical committee and is an author of several chapters in the Visual Effects Handbook. Scott Squires serves as consulting visual effects supervisor for Legend3D. He maintains a very popular blog The Effects Corner read by many visual effects professionals. 

Carlos G. Perez-Garcia, Ph.D. is Senior Research Associate in neuroscience at the Salk Institute. He is considered an expert in human neuro-anatomy and molecular genetics in developmental neuroscience. His career is focused on the study of genes involved in embryonic development of human and mouse neo-cortex – specifically the study of the defects caused by deficiencies of those genes in human brain disorders such as lissencephalies and double cortex syndrome as well as schizophrenia and bipolar disorders. Dr Perez-Garcia is also a collaborator in the study of neurological aspects of genes strongly expressed in a variety of cancers/tumors in human central nervous system.

Wednesday, February 1, 2012

Engaged in 2D and Immersed in 3D

This month, the multiple 3D films being recognized by the 84th Academy Awards cement the fact that 3D is here to stay. On the heels of the Best Visual Effects nominations for Hugo and Transformers: Dark of the Moon, Legend3D Founder, President, CCO/CTO Barry Sandrew dissects the appeal of 3D for the moviegoer in this two-part blog series on the neuroscience of 2D and 3D feature films. Relying on our current understanding of stereopsis, as described in scientific literature, Sandrew contemplates how our brains differentially perceive images and activate emotional responses when viewing a 2D movie versus a 3D movie.

The group dynamics of the 2D experience

When we attend a 2D movie, the group dynamics of the audience come into play as we direct our collective attention as observers to the images on the screen. Our personal space is infringed upon only tangentially by the other audience members that are sitting on either side of us, as well as by those behind and in front of us. The tangential influence upon us of the surrounding audience is a reminder that we are in a theater with strangers, all watching images being projected on the screen. However, in a 2D movie, our fellow audience members typically do not detract from the experience.  In fact, the audience in a 2D movie is intended to be an integral part of the total feature film experience and has been presented as one of the selling points of attending a 2D move in a theater rather than watching it on DVD or Blu-ray at home. As we become engaged in the movie, we can introspectively sense surprise, anger, sadness and happiness based on the perceived action on the screen and to a lesser degree, through the reactions of the audience members around us. We can empathize and sympathize with the characters being portrayed and we can experience anxiety and fear as we follow the storyline.

DisparityA key element in the perception of stereo

Our brains receive 2D information in a theater as images presented sequentially at 24 frames per second. In a 2D theater experience, motion is perceived as changes in the up, down and sideways position of one object in relation to other 2D objects.  We perceive three dimensions in a 2D movie via single eye or monocular cues such as occlusion, motion, shading, size, parallax, texture gradient, perspective, saturation and brightness. However, lacking in a 2D movie is the most powerful 3D influence on the brain—disparity. Due to the separation of our eyes and the distance between them, we see a slightly different image from each eye.  This separation causes a horizontal displacement between the images, which is referred to as disparity. The best way to test this is to put your thumb in front of your eyes and alternately close one eye and then the other. You will see two separate perspectives of your thumb displaced horizontally and your thumb will appear to jump from side to side. When these separate images from our left and right eye reach our visual cortex, they are directed to highly specialized neurons that are tuned to critical parameters of disparity.  As a consequence, the two images are fused into one uniquely different image that exhibits the appearance of depth and volume. The result is 3D perception.

A lack of disparity contradicts monocular cues

In a 2D movie, each of our eyes receives precisely identical images from the movie screen with no horizontal displacement. When the two sets of identical images reach the visual cortex of our brain, they are directed primarily to neurons tuned to zero disparity. There, they are “fused” together into a single image that is exactly identical to each of the two images that originally comprised it. Other than the existence of monocular stereo cues, mentioned above, the audience does not perceive depth and volume due to the absence of disparity. This lack of disparity in a 2D movie creates a cue conflict situation that prevents us from being fully immersed in the story in the same manner as a 3D movie. The monocular cues in a 2D movie are telling us there is depth, but the lack of disparity contradicts the monocular cues—forcing the brain to try and reconcile the conflict.

The absence of disparity “pushes” the screen away from us

For some monocular cues, like motion and occlusion, there is a further complication that acts to distance us from the movie screen. As mentioned above, in a 2D movie the relative motion of objects on the screen (one 2D object moving relative to and possibly occluding another 2D object) can indicate depth in the absence of disparity. However, in the real world when there is this kind of relative motion in the absence of disparity, our brains normally interpret that information as indicating that the objects are far away. That’s because disparity in human vision drops off significantly at distances of several hundred yards.  You can prove this if you try the thumb trick above, alternately closing one eye and then the other, but this time, try the trick looking at a tree that is several hundred yards away.  You’ll see that the tree will not appear to jump from side to side like your thumb did. This is because the perspectives from our two eyes at that distance are identical. Our eyes do not converge on the tree, but rather are set to infinity.  The father away things are from us the less horizontal displacement we experience.  So our brain “comes up with” a solution in which we are literally “distanced” from the action on the screen. This distancing and lack of disparity in a 2D movie renders the spatial areas in front of and behind the theater screen irrelevant to the story and therefore irrelevant to each member of the audience. The storytelling, in its entirety, happens on the white screen at the end of the theater.

Skillful use of disparity in a 3D movie will always enhance the experience

In spite of the contradictions our brain must reconcile, a 2D movie is almost always comfortable to watch and with proper directing, cinematography and storytelling, it can evoke very strong emotions. Indeed, many of us remember the outpouring of emotions while watching the sinking of the Titanic or the building terror of T-Rex in Jurassic Park, as both movie experiences were presented in 2D. However, the influence of disparity on the audience in a 3D movie cannot be trivialized as a fad or unnecessary. Whether a 3D movie is captured with two cameras or converted from 2D-to-3D, disparity that is properly and skillfully stereographed will always enhance the storytelling experience by significantly amplifying the responses of disparity-tuned neurons and therefore more closely simulating reality.

3D a higher resolution medium

In the visual system, the absolute number of neurons activated in the brain is not as significant as the ratio of activation between subpopulations of neurons responding to zero disparity and those responding to a wide spectrum of tuned disparities, including zero.  This is analogous to an audio amplifier where the ratio between subpopulations of audio frequencies can vary and increasing the gain on the system increases the overall fidelity of the audio experience, meaning it becomes closer to the original source in resolution.  In the same manner, the ratio of activated zero disparity and disparity-tuned subpopulations of neurons in a 3D movie can vary, but it’s the intensity of the relative responses of those subpopulations that create a more accurate and higher resolution stereo image.  It appears that our brains interpret this higher resolution information as more closely simulating reality (“fidelity”) and therefore it immerses us in the movie to a greater degree, creating a heightened emotional investment in the story.  This is, of course, an oversimplification of an exquisitely complex process that has evolved from the earliest primates. However, the theater going experience is something we can all relate to and many of us recognize the profound difference between being engaged in a 2D movie versus being immersed in a 3D movie.

3D movies are a uniquely personal experience

Dynamic disparity (i.e. the relative amount of disparity, changes in disparity over time and the rate of disparity change) transforms the movie screen from a projection screen into a window that has both an interior and an exterior. Consequently, the storytelling environment is projected throughout the entire theater, actively becoming a unique part of the personal space of each member of the audience and resulting in the space both in front of and behind the screen becoming an integral part of the story. For example, an object that might fly out of the screen at us, traveling through what is called negative parallax, becomes very personal for each member of the audience because it affects and/or “intrudes” each audience members’ personal space equally.  Surround sound has an analogous effect in that we are “in it” rather than simply listening to stereo audio in front of us.  As a result, unlike the 2D movie experience, a 3D movie is more personal and the group dynamics of the larger audience are no longer in play to the same extent.  In fact, it’s my opinion that 3D glasses actually have the positive effect of helping to separate us from the other audience members, containing the experience as a more personal one for each of us, thereby potentially amplifying the immersive nature of the experience.

The Bottom Line

When we are engaged in a 2D movie, we are doing so as passive observers, watching the story take place “over there”, on the screen in front of us. However, when we are immersed in a 3D movie, we are doing so as active participants and the action can be happening behind and in front of us—as far as infinity. This is where the central difference lies. We cannot discount the uniquely active physical and emotional reactions that we have in the 3D feature film experience which are not experienced in our more passive reception of 2D movies. I believe, this is one of the reasons why we have seen 3D continue to flourish and be adopted so enthusiastically by both national and international movie exhibitors, as well as by the entertainment and consumer electronics industries at large. Consumers and moviegoers are hungry for visuals that offer a significantly greater sense of engagement and for visuals that spark an immersive, emotional response that has the ability to transport them into the heart of the action.  This year, we will have the opportunity to test the differential 2D and 3D theatrical experiences with three iconic movies that were originally released in 2D, being released in 3D. Top Gun has been converted by Legend3D and will be re-released on its 25th anniversary by Paramount on the heels of 3D converted re-releases of Titanic and Star Wars.  I am confident that all three films will be very successful at the box office, as each was already a proven success in 2D. Depending on how skillfully each of these films was converted, now in 3D they will give those who saw them originally in 2D an immersive and refreshingly unique experience; an experience that will hopefully help to solidify 3D as an essential part of filmmaking.

Next, we will continue to look at the neuroscience of 3D movies and further explore the uniquely tuned structures and neurons in the brain that respond selectively to dynamic disparity. We’ll look at concepts of visual processing that remain contentious within the scientific community, involving differential pathways within the brain that signal separately “where something is” and “what something is.” The evolutionary survival value of binocular vision will be discussed in the context of 3D movies and we will touch upon more primitive structures in the brain that are likely triggered by disparity to elicit powerful physical emotions and ‘flight’ or ‘fight’ reactions. For more detailed information and technical reviews on stereopsis, as well as in-depth information on the uniquely tuned disparity neurons in many parts of the brain, please see the following references:

(1) Cumming BG, De Angeles GC. (2001). The Physiology of Stereopsis. Annual Review of Neuroscience. 24, 203-238.

(2) Howard, IP, Rogers, BJ. (1995). Binocular Vision and Stereopsis.  New York: Oxford University Press.

(3) Poggio, GF, Poggio, T. (1984). The Analysis of Stereopsis.  Annual Review of Neuroscience. 7, 379-412.

(4) Born, R., Bradley, D. (2005). Structure and Function of Visual Area MT. Annual Review of Neuroscience. 28, 157-189.

I wish to acknowledge the review and insightful suggestions of my neuroscience colleague, David Heeger, Ph.D., Professor at New York University ( where he is a member of the Center for Brain Imaging. The son of Nobel laureate and chemist, Alan J. Heeger, David Heeger is a contemporary neuroscientist who has been at the forefront in the field of functional magnetic resonance imaging (fMRI). Dr. Heeger was the first to bring together two separate and largely unrelated disciplinescognitive neuroscience and film studies, opening the way for the exciting new interdisciplinary field of “Neurocinematic” Studies.