Mixed Messages: How your brain deals with conflicting information

October 17th, 2023

Written by: Barnes Jannuzi

Mixed Messages

Every waking moment your brain is abuzz with activity, constantly trying to take in the chaotic and beautiful sensory world around you. But your brain does so much more than passively absorb information. It actively warps the signals coming from your sensory systems such as your eyes and ears. To put this another way, you do not directly see, feel, hear, smell, or taste the real world; but rather you perceive an altered and filtered interpretation. This may sound a bit off-putting, but it allows for a seamless understanding of a complex environment that is always changing. One of the most important ways your brain alters what you perceive is by accounting for disagreements between information coming into your brain from your senses. This conflict can either be within a sense, or between two different senses. Your brain successfully mediating these conflicts in sensory information allows you to have amazing abilities such as seeing in three dimensions, while failures to solve conflicts can cause confusions in understanding and even you getting carsick. To put it simply, your brain resolves conflicts and mixed sensory messages to allow you to better understand the world around you. In this article you will learn about some examples of how your brain processes mixed messages; how it gets things right, how it gets confused, and when things get a little strange.

The Good

Your brain successfully resolves many sensory conflicts while you are not even aware it is happening. Let’s start with the two seeing spheres in the front of your face. The fact that you have two of them is a big difference between your eyes and a simple camera, and it makes sensory conflict resolution a must for the brain. Although similar, each eye sees a slightly different view of the world  in front of you. This phenomenon is known as ocular disparity¹.  Every moment you look at something, your brain is taking the two separate viewpoints from your eyes and merging them into one visual experience. Having these two viewpoints allows you to see in three dimensions. Interestingly, your view of the world likely doesn’t come equally from both eyes. Just as many people have a dominant hand or foot, there is often one eye that is dominant to the other, meaning that when the brain resolves the conflict of viewing angle between the two eyes, it defaults to using the information from the dominant eye most of the time. 

Try it yourself!

To figure out which eye is your dominant eye try this: With both eyes open, point at something in the distance like a clock on a wall or a mountain peak. Put your finger so that your fingernail is right under what you are pointed at. Holding your arm still, close your left eye, are you still pointing at it? Now repeat this, only this time close your right eye. Are you still pointing at it now? You likely noticed that after closing one of your eyes you were no longer pointing at the object. By closing an eye, you have cut off the sensory information your brain was receiving from it. If shutting an eye changed where you were pointing, it means that your brain had been using the information from that eye as the dominant information. However, now that it is not getting information from that dominant eye, it will change which eye it is relying on to and in doing so, change where your finger appears to be pointed. Put simply, Whichever eye being closed caused you to no longer be pointing at the object is your dominant eye. Eg. If closing your left eye caused you to no longer be pointing at the object, you are left eye dominant. If closing your right eye caused you to no longer be pointing at the object, you are right eye dominant.

These conflicts don’t just happen within vision, but for other senses like hearing as well. Similar to your two eyes viewing the world from different angles , your ears hear the same thing at slightly different times. This tiny time lag allows you to pinpoint where a sound is coming from. Despite these lags, you’ve probably never actually perceived the sound hitting your ears at different times. Typically, you simply perceive a single sound in both ears at the same time that comes from a particular direction. This effortless, unconscious processing and resolution is critical for your smooth perception of the world, and is a brilliant example of how important it is for your brain to solve mixed messages. But what happens when this sensory conflict resolution does not work out as well?

The Bad

Mixed sensory messages do not just happen within senses, but also between them. Being able to use all of your senses together enables us to perceive the world in a much richer way. However, more sensory information means more sensory conflict which needs to be resolved by the brain. When these conflicts are not properly resolved, it can lead to some unpleasant failures. Have you ever driven down a windy road when suddenly your stomach started to spin? Motion sickness can be associated with a variety of symptoms, however none is more infamous than nausea and vomiting^2,3. Motion sickness is thought to be caused by a failure to resolve conflicting sensory information between vision and body position/movement. . When moving fast in a car, or while using virtual reality technology, there is a mismatch between how much your body is expecting to move based on what you can see, and how your body feels like it is accelerating based on some internal receptors of motion. This is believed to be caused by something known as the sensory conflict theory⁴, and when the discrepancy between these two senses is too great, you get motion sickness. 

The Strange

Finally, sometimes your brain resolves sensory conflict in strange ways that are not necessarily distressing, but are fascinating and can seem a little odd. The Mcgurk Effect⁵ is an auditory illusion where the same noise/sounds are perceived differently depending on what you see. For example, this video demonstrates a compelling example where a looping sound of  “BAH BAH BAH” is played as someone mouths the sound “BAH BAH BAH” and “FAH FAH FAH”, changing how you hear the same sound and molding it in your mind to what was mouthed. What is so compelling about this illusion is that even after knowing what your brain is doing, it is difficult if not impossible to only hear “BAH BAH BAH” while looking at someone mouth the sound “FAH FAH FAH”. 

To see the World

Perceiving the world is anything but a passive process for the brain. It is a constant battle by your brain to take the bombardment of information from all senses and convert it into an understanding of the world around us. It is astounding how much of this battle goes on without your direct awareness; the good, the bad, and the strange. However, perception is the foundation of everything you do and know, and it is therefore important to understand the power and equally so, the limitations of your own ability to make sense of what you see, hear and feel. 

References 

1. Gardner JC, Raiten EJ. Ocular dominance and disparity-sensitivity: why there are cells in the visual cortex driven unequally by the two eyes. Exp Brain Res. 1986;64(3):505-14. doi: 10.1007/BF00340488. PMID: 3803488.
2. Zhang LL, Wang JQ, Qi RR, et al. Motion sickness: current knowledge and recent advance. CNS Neurosci Ther. 2016;22(1):15–24. doi: 10.1111/cns.12468.
3. Lackner JR. Motion sickness: more than nausea and vomiting. Exp Brain Res. 2014 Aug;232(8):2493-510. doi: 10.1007/s00221-014-4008-8. Epub 2014 Jun 25. PMID: 24961738; PMCID: PMC4112051.
4. Kohl RL. Sensory conflict theory of space motion sickness: an anatomical location for the neuroconflict. Aviat Space Environ Med. 1983 May;54(5):464-5. PMID: 6870740.
5. MCGURK, H., MACDONALD, J. Hearing lips and seeing voices. Nature 264, 746–748 (1976). https://doi-org.proxy.library.upenn.edu/10.1038/264746a0

Cover Photo by Jos van Ouwerkerk on Pexels.