The Dress
In 2015, a badly-taken photo of a dress caused mayhem on the internet. Some were adamant that the dress was blue and black; others believed that it was white and gold. Either way, the image drew the attention of many illusion researchers who were equally confused.
Pascal Wallisch, a neuroscientist at New York University, was among these researchers. He wanted to understand why different people were seeing different colors. Scientists in the field of optics have long accepted the theory that we come to a judgment by unconsciously filtering out the type of light that we believe shines on an object. As such, he deduced that people made different assumptions about the quality of light being cast on the dress; some people would have assumed it was natural light while others would have assumed it was artificial indoor light.
But why? According to Wallisch, these assumptions were due to chronotype— the time when you usually go to bed. Wallisch wanted to test his theory, so he created an online study that consisted of 13,000 people. The survey results concurred with his hypothesis; Wallisch found that night owls were more likely to see the dress as black and blue, whereas early risers (or larks) were more likely to see it as white and gold.
Therefore, it was not any complex slight of the mind that resulted in the disagreement among the internet users, but rather their different life experiences—of being either a lark or a night owl—which led the internet users to see the dress in distinct lights. Since larks spend more time in the daylight, they are more likely to assume that the dress is being bathed in bright sunlight. Their brains will filter the blue lightning out, and they are left seeing white and gold. On the other hand, night owls are more likely to assume that the dress is under artificial lighting, and filtering that out makes the dress appear black and blue. Nonetheless, Wallisch admits that the case is not closed. “There are still lots of other factors that must have a strong influence here. It could be prior experience with the subject matter, or related to other aspects of people’s personality,” he says.
The dress is merely one example in a plethora of others that mystify researchers and neuroscientists alike. This image of a strawberry tart created by Japanese researcher Akiyoshi Kitaoka is another optical illusion that deals with color. To any normal person, the strawberries will appear as red, but they are actually gray. The coined concept for this phenomenon is called “color constancy,” which refers to our ability to perceive colors as relatively constant over varying illuminations.
These two optical illusions tell us a lot about the way our brain perceives and processes ambiguous, or even missing visual information.
Moreover, our ability to perceive depth, movement, and shapes is also limited. Many people, at this point, make the assumption that our brains are the source of these errors. However, while most optical illusions result from processes in the cortex, some can originate in the retina. One such illusion is the Hermann grid. The grid features gray spots at the intersections of the squares because of a phenomenon called “lateral retinal inhibition”. If you stare directly at one of these intersections, the gray spot disappears, and the intersections begin to look white. Experts say that this phenomenon is because your eyes switch to using the cells of the fovea after a period of time, which do much less correction.
According to some researchers, our brain limits the information it receives due to the substantial amount of information that we are exposed to every second of the day. The task is not only overwhelming, but also unnecessary; if we were to remember every detail, we would not have space to store the more important information. Consequently, some information is distorted, resulting in visual illusions.
Susana Martinez-Conde, a neuroscientist and illusion researcher at SUNY Downstate Medical Center, suggests that even if we had the capacity to process all of this information, “we wouldn’t even want it.”
In closing, while our eyes and our brain are accurate for the most part, we should not assume that we know the world in its entirety. In order to adapt to its environment, our brain constantly makes assumptions about the world—educated guesses, if you will. Nonetheless, as these optical illusions teach us, the reality that we perceive is quite separated from whatever reality lies out there. Knowing this, we should approach our perception with greater care.
Resources:
https://thebrain.mcgill.ca/flash/a/a_02/a_02_p/a_02_p_vis/a_02_p_vis.html
Others to read:
https://www.all-about-psychology.com/optical-illusions.html