At first glance what do you see -- a young woman? Or perhaps a smooth jazz artist? This classic optical illusion occurs due to a phenomenon known as binocular rivalry. Here, the brain is presented with two images simultaneously. Instead of superimposing the two images, the brain suppresses the image input from one eye, making the input from the other more dominant.
Looking at this visual illusion, binocular rivalry means your brain can only perceive a single image at a time - quickly toggling between either the woman or the saxophone player. In this video by BrainCraft, the mechanism by which this optical experience occurs is explained.
The interest in binocular rivalry goes back to the Greek philosopher Aristotle, who theorized that sensory information from each eye is fused together into one, resulting in us viewing the world as a singular mash-up. Today, binocular rivalry has disproven Aristotle’s theory and is now a commonly-used empirical tool for studying perception and consciousness.
Earlier this year, scientists from Johns Hopkins University and the Department of Psychological and Brain Sciences at Dartmouth University discovered that binocular rivalry could also be an early diagnostic marker of autism.
People on the autism spectrum can experience extreme hypersensitivity to everyday sensory stimuli, including visual overload. Researchers are now able to link these sensitivities to an inability to focus and gain clarity when presented with complex visual stimuli like bright colors, intricate patterns or flashing lights.
To test their hypothesis, researchers hooked up electrodes to autistic and neurotypical participants to measure their brain activity. They were then shown patterned pictures, with two different colors shown to each of the left and right eyes. The autistic participants struggled significantly with shifting their attention between the two images using binocular rivalry, as compared to the neurotypical group.
By using the rate of binocular rivalry as a measurement, the researchers were able to predict how advanced the symptoms of autism were in an individual with impressive accuracy. Using this new methodology, they were able to correctly predict that a participant was on the autism spectrum 87 percent of the time.
The neuroscientists are hopeful that this will serve as a simple, non-verbal diagnostic tool for autism in the future.