Are These Dots Purple, Blue Or Proof That Humans Will Never Be Happy

February 21, 2019

A new optical illusions study in the journal Science asks whether a series of colorful dots is purple, blue or proof that humans are destined for a lifetime of grief and bad decisions.

In the study, published on June 29, a team of scientists from Harvard, Dartmouth and New York University showed a series of 1,000 dots, which ranged in color from very blue to very purple, to several groups of U.S. college students. (You can see the full spectrum in the video below.) The participants only had to answer one question. Are the dots on the screen blue or not?

It sounds simple enough, and at first it was. For the first 200 trials, participants saw an equal number of points in the blue and purple parts of the spectrum, and most participants were able to recognize the difference well. However, over the remaining 800 trials, the number of blue dots steadily declined until participants saw almost exclusively shades of purple. Perversely, their answers didn’t reflect this.

The researchers wrote in the study that “as blue dots became rare, participants began to see purple dots as blue”. In fact, in the final 200 trials, dots that participants had previously identified as purple now appeared to them to be blue. Participants continued to mistake purple dots for blue dots even though they were specifically warned that the number of blue dots would decrease, or when they were offered a $10 reward in response to repeating the color at the end of the study in the same way they had at the beginning of the study.

So why the sudden change in perception? The researchers believe it may be that the human brain doesn’t make decisions based on cold, hard rules, but rather on previous stimuli. As the balance of blue to purple dots changed, the participants expanded their definition of what exactly “blue” looked like to match the expectations formed by previous experiments.

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The bottom line here, as with most optical illusions, is that your magnificent human mind is really, really easy to deceive. No news there. But to demonstrate some of the potential real-world consequences of this mental design flaw, the researchers went a step further and conducted two more experiments in which the “blue or purple” decision was replaced with something heavier.

In a follow-up experiment, the researchers showed participants 800 computer-generated faces that varied on a continuum from “threatening” to “non-threatening.” When the number of malicious mug shots the researchers showed participants decreased after 200 trials, participants began to label the non-threatening portraits as threatening.

These results were replicated in a final experiment in which participants were presented with 240 proposals for a fake research project. These mock proposals ranged from the ethical (e.g., “Participants will list the cities around the world they would most like to visit and write down what they would do in each city”) to the unethical (e.g., “Participants will be asked to lick a frozen piece of human feces…”). . . will measure the amount of mouthwash used [afterwards]”).

The participant must then decide whether the proposed experiment should be allowed to proceed. When the study was halfway through, the number of unethical proposals decreased and the participants changed their minds again and began to rate the ethical proposals as unethical.

“These results may have sobering implications,” the researchers wrote.

If your brain is constantly recalibrating its perceptions based on previous experiences, how can you be sure that you ever really saw something? On a larger scale, if human societies keep expanding their definitions of these problems to include new transgressions, can they actually solve their problems – crime, poverty, prejudice, etc.?

“While modern societies have made extraordinary progress in solving a wide range of social problems, from poverty and illiteracy to violence and infant mortality, most people believe the world is getting worse,” the researchers conclude. Perhaps, they say, the more problems a society solves, the more that society expands its definition of a problem. It’s not that the glass of water is only half empty; maybe we just perceive the glass in front of us as getting bigger.