Illusions at work


We say that “seeing is believing,” but visual illusions can trick us, whether we’re looking at checkerboards or human faces. How can we outsmart them?


NARRATOR: Want to catch your brain making a mistake in real-time?

Take a look at this checkerboard, created by vision scientist Edward Adelson.

The squares labeled “A” and “B” are exactly the same shade of gray.

Don’t believe me? I don’t blame you. I see them as different too.

But here’s the proof: simply connect the two with this gray bar, and voilà! Suddenly, it’s obvious: A and B are identical.

Here’s the strange thing: remove the bar and the illusion comes back immediately, just as strong as it was before. We can do this again for the skeptics: different shades of grey; same shades of grey; different; same. Our eyes can see that A and B are identical. But our brains fall for it every time, no matter how often you debunk the illusion. Why?

Professor Adelson points to two specific details of his illusion:

First: contrast. “A” looks darker because it’s surrounded by lighter-colored squares.The opposite is true for “B.”

Second: Take a look at the soft edges of this darker section. Our brains see this and think “Ah, it’s a shadow.” We know that objects in shadows look darker than they actually are, so our brains compensate for that by making us actually see “B” as lighter.

Something else to consider? We all know what a checkerboard pattern looks like. So we come into this illusion already expectingA and B to be different, and that could influence what we see.

What about our expectations about people?

Which face is darker? The one on the left? Or the one on the right?

Psychologists Daniel Levin and Mahzarin Banaji found that most people (including Mahzarin herself!) see the Black face as darker than the White face, even though the two faces are the exact same shade of gray. Again, debunking the illusion is simple; here’s an idea from Dan:

DANIEL LEVIN: Just cover up the lower parts of the faces. You’ll be left with two foreheads, and they’ll look exactly the same.

NARRATOR: Clearly, the features of the face matter. But in a second study, the researchers showed that you could create this illusion using the same face. People saw a racially ambiguous face labeled “Black” as darker than the same face labeled “White.”

Did you?

Think about what this means: We see two faces. They are identical. But we’re so used to associating different races with different skin-tones that we misperceive a simple physical reality. All because of a single word. That’s how powerful our expectations are.

Now, when it comes to judging the brightness of objects, the errors seem pretty harmless. But research shows that we also see the exact same action as being less “bad” if the perpetrator is attractive; we rate the same musician as more masterful if she’s described as a “natural” rather than a “hard-worker.” These illusions are more costly.

So how can we base our decisions on fact rather than fiction?

Think back to how we debunked illusions before: we needed to have the two tiles, the two faces in front of us at the same time to really prove the truth. So when you have multiple options in front of you (whether it’s job candidates or health insurance plans), consider them side by side. Not only does this let you test your intuitions, research shows that you’ll be more likely to. When people evaluate things together, they’re more likely to use the same specific benchmarks to compare them.

Want something stronger? If you want to avoid illusions altogether, try blinding. We’ve talked about this technique before: when orchestras put a curtain between musicians and judges during auditions and let the music do the talking, a new crop of players rose to the top.

Sometimes we perceive more than what meets the eye. But a few tweaks to the process can help outsmart your mind.


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There are illusions we all fall prey to, like Ted Adelson’s Checker-Shadow illusion or Roger Shepard’s table tops. But some perceptions vary from person to person. Remember this dress? Was it black and blue or white and gold? This simple question set fire to the internet in 2015. The real dress was black and blue… so why did some people see something so different? It turns out that the colors we “see” change depending on how our minds interpret the source of light in the photograph. Read more about the science behind the illusion at Wired.

Just as a face labeled “Black” or “White” looks darker or lighter, or how a musician labeled a “natural” or a “hard-worker” sounds different, the name at the top of a resume can change how qualified we think a person is. To learn more, read our article Can women be biased against other women? and listen to our podcast Race bias in hiring: When both applicant and employer lose.

“Some 51% of the employers who considered candidates individually chose an employee who had underperformed relative to the group. By contrast, only 8% of the employers who considered candidates side-by-side chose underperformers.” How does simultaneous evaluation help us see talent more clearly? Read more about the research at The Wall Street Journal.

“Most companies say they want to attract a diverse workforce, but few deliver. The only solution may be a radical one: anonymity.” Find out how Silicon Valley is taking steps towards a more diverse workforce (New York Times).


Basu, S., & Savani, K. (2019). Choosing Among Options Presented Sequentially or Simultaneously. Current Directions in Psychological Science, 28(1), 97-101.

Dion, K. K. (1972). Physical attractiveness and evaluation of children’s transgressions. Journal of Personality and Social Psychology, 24(2), 207-213.

Goldin, C., & Rouse, C. (2000). Orchestrating impartiality: The impact of” blind” auditions on female musicians. American Economic Review, 90(4), 715-741.

Levin, D. T., & Banaji, M. R. (2006). Distortions in the perceived lightness of faces: the role of race categories. Journal of Experimental Psychology: General, 135(4), 501.

Tsay, C. J., & Banaji, M. R. (2011). Naturals and strivers: Preferences and beliefs about sources of achievement. Journal of Experimental Social Psychology, 47(2), 460-465.


“When seeing shouldn’t be believing: Illusions at work” was created and developed by Olivia Kang, Moshe Poliak, Kirsten Morehouse, Evan Younger, and Mahzarin Banaji. Research and Development Assistants for this episode include Moshe Poliak and Megan Burns. Support for Outsmarting Human Minds comes from PwC, Johnson & Johnson, and Harvard University.

Narration by Olivia Kang, featuring Professor Daniel Levin (Vanderbilt University)

Animation and Editing by Evan Younger

Artwork by Evan Younger and Olivia Kang

Checker Shadow Illusion image created by Edward Adelson

Music by Peter McIsaac Music, Origami Pigeon, Immersive Music, and Taizo Audio via Premium Beat.