Mouse Reactions to Optical Illusions: How This Can Guide Our Understanding About Consciousness

By Hunter Shaw

The goal of a visual illusion is to guide your brain into the event of disassociation between physical reality and subjective perception.  When we focus our attention onto these images or objects, areas in the brain have been observed to light up.  Subconsciously, your brain will predict the image’s context by falsely filling in “missing pieces” in areas that may trigger a sense of familiarity.  For reference, if you were to direct your attention to the top image, you will observe there to be a Coca-Cola can.  You may also perceive the can in the image to be red.  Now, if you look closer, you will find that the can is black and white.  With previous knowledge of what a Coca-Cola can look like, your brain essentially predicts and falsely perceives the physical state of the image.  Although the can is not red, the trademark design of the can being imprinted in your mind allows for it to subconsciously form a familiar perception of the external environment.

Applying similar concepts, a new study uses the neon-color-spreading illusion (as seen in the bottom image).  This illusion uses four primary circular structures consisting of smaller circles, stacked 2-by-2.  Parts of the circles are a lime green, and the rest, black.  Combining the four structures, the lime green sections form one large circle structure in continuity between the four primary circles.  When directing your focus to the illusion, the brain may detect the green circle as a solid shape – thus forming a solid border around the green circle.  Additionally, the green circle can be described as relatively “bright” – given it’s neon characteristic.  Masataka Watanabe and colleagues at the University of Tokyo of the department of systems innovation discovered a technique that allows them to dive into the minds of rodents’ brains while they observe the neon-color-spreading illusion.

As part of the experiment, they focused on the physical reaction of the eyes of mice when observing the illusions.  As a result, they found that their eyes constrict in response to the brightness of the green circular formation.  It was further assessed that there was a high neuronal reaction within the area of the brain that receives and perceives visual data, specifically light.  Using a 6 layer system of neurons (brain cells) , the visual system processes visual data; sixth being most complex and first being least complex.  Like this test, another test (the control examination) was conducted, however the illusions did not cause perception using color.  Consequently, the mice’s eyes did not constrict.  Using implanted electrodes, Watanabe observed the mice’s visual system did not process a change in light.  These results directly correlate to how humans react to and perceive changes in light levels, as well as how we process visual data.

The data from this study allows for understanding the event of consciousness, as this study proves, the brain uses a technique called top-down processing.  As the visual data travels through the layers of brain cells, different information is processed, consequently constructing an image.  This is how we interpret our surroundings in every given moment.  Not solely relying on visual stimuli, the brain utilizes prior experiences. The contrast example would be bottom-up processing, which is the act of building a picture or perception of the surroundings, by putting pieces of the environment together.  This would typically consist of combining all senses; memory is not involved in this event.

Being conscious as humans, we absorb our surroundings based on level of familiarity from a top-down process.  Your brain will recognize smells, objects, settings and sounds of any spectrum that allow for perception of any external environment.  The physical ability to perceive an environment, as proven by Watanabe, utilizes surrounding stimuli to construct a reality.  Considering what we discussed today, and considering the two referred optical illusions, how much do we perceive is actually a TRUE reality?

References

Macknik, Stephen L., and Susana Martinez-Conde. “The Neuroscience of Illusion.” Scientific American, 20 Feb. 2024, www.scientificamerican.com/article/the-neuroscience-of-illusion-2010-05/.

“Watanabe Masataka: 東京大学大学院システム創成学専攻.” WATANABE Masataka | 東京大学大学院システム創成学専攻, www.sys.t.u-tokyo.ac.jp/en/memberpage/3366/?lang=en. Accessed 9 May 2024.