Binocular Rivalry—Competition, Connection, and Consciousness

  • Published14 Sep 2017
  • Reviewed14 Sep 2017
  • Source BrainFacts/SfN

Your brain combines information from each eye to form a single picture of the world. But what happens when each eye sees something different? This video explains this phenomenon, called binocular rivalry, and how it is applied in various fields of research.



Hi, my name is Anirudh. When my brother and I fight, my mum often says that we are like her two eyes. After researching the subject of binocular rivalry, I realized that this was a figure of speech, and certainly not the case.

The phenomenon of binocular rivalry occurs when two distinctly different images are presented to each eye simultaneously. The observer though, is only aware of one image at a time. There is a random switching between the images from each eye, creating a rivalry between both eyes. Sorry mum, your figure of speech isn’t quite right!

To create binocular rivalry, each eye has to be presented with a different image. This can be achieved in several ways such as anaglyph glasses, mirror stereoscopes or prism glasses. For simplicity, I will be using anaglyph glasses, commonly known as 3D glasses.

In order to understand binocular rivalry, first let me explain how the brain processes images. Each of our eyes normally see slightly different images and the brain fuses these images into one. However, when presented with two distinctly different images, the brain does not merge these images, instead, suppressing one image and making the other dominant. This process continues indefinitely.

Visual attention flickers between the two images causing binocular rivalry. When the brain processes two distinctly different images, signals run through the optic nerve and to the brain, processing each individual image separately. The group of neurons processing the dominant image inhibits the group processing the suppressed image. After a while, the system fatigues and then the suppressed image becomes dominant. This processing of the images switches from time to time and continues indefinitely.

Now, I hope that you would have some understanding of binocular rivalry. I know what you are thinking. What is the use of this? Though there is no direct application of this phenomenon, it facilitates understanding of some of the complex mechanisms of the brain. Let me go through a few recent studies. There is no better way to explain the usefulness of this phenomenon.

We often find it hard to adjust to changes that we are faced with throughout our lives, but did you know our brain is adapting to change quicker than we think? Our brain is constantly changing, every minute, every second of our lives - adapting to the environment. This amazing ability, called neuroplasticity, is what makes it unrivalled in comparison to machines and computers.

Let me explain how Pisa Vision Lab utilized the phenomenon of binocular rivalry to test that the brain can easily adapt to change and makes new connections within short timespans. They measured binocular rivalry in normal settings and again after patching one eye for two and a half hours. The results showed that the patched eye was more dominant than the other.

The concentration of a neurotransmitter, Gamma Amino Butryic Acid, GABA for short, may trigger neuroplasticity.

The research concluded:
• The change in resting GABA strongly correlates with deprived eye perceptual boost
• A decrease in resting GABA triggers homeostatic plasticity in adult primary visual cortex

This is a classic example of how researchers use the phenomenon of binocular rivalry to test some of the amazing abilities of the brain such as neuroplasticity.

You may be wondering why I am meditating. What is this got to do with binocular rivalry? Well, consciousness is the state of being aware and alert in your surroundings. Among neuroscientists there has been contention around the precise identification of the neural correlates of consciousness.

The study of binocular rivalry attempts to understand this phenomenon. A recent study by Olivia Carter and Jack Pettigrew explores whether focused meditation can lead to a higher level of control and stability of mental processes. The results were quite interesting and concluded that meditation could actually slow down or even stop binocular rivalry. These results conclude that the fluctuations in visual perception can be stabilized through focused meditation. This creates a stabilization of mental processes and, is a step forward in our understanding of the neural correlates of consciousness.

The phenomenon of binocular rivalry can be used as a basis to understand neural processing in many different fields. Researchers use the concept of binocular rivalry to understand some of the complex mechanisms of the brain. So, not all rivalries are bad. Sometimes we can learn from them! So.... does that mean we can fight now?

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