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How Statistics Fool Juries

Peter Donnelly is a statistician with a sense of humor. He starts his talk with a classic statistician joke: "How do you tell an introverted statistician from an extroverted statistician? The extrovert is the one who looks at the other person's shoes." But he's not all fun and games. In a 2005 TED Talk, Donnelly explains a little about with it's like to be a professional statistician, then launches into a fascinating explanation of how statistics are misunderstood by typical audiences. He gives examples for the audience to examine (a few multiple-choice questions), to prove his point -- and I'll admit, he got me. I didn't get the examples right, though I was pretty confident in my answers.

This reminds me of when I was on a jury room in a personal injury case. While my experience wasn't related to statistics, it was an issue of science which seemed like we should have been able to prove the right answer one way or another -- but we failed. The jury had an hour-long argument about physics, trying to determine whether a driver's upper body in a car would be pushed forward or backward when the car was hit from behind. (There was a key question regarding whether a specific injury could have been caused by the impact, or was a pre-existing condition.) We even built a model, but that failed to convince anybody of what the real-world behavior would be. Everyone on the jury insisted that his or her own mental model was correct (which tended to align with their gut feeling about the guilt or innocence of the defendant), and neither demonstrating the physics of the situation, nor thinking through it with a shared mental model made any difference. It was an interesting day, to say the least. (See also: whiplash.)

Anyway, Donnelly's talk is a great example of how attorneys (or really anyone) can exploit general misunderstanding of statistics in order to make an invalid point -- and most of us won't notice that anything is wrong. There's even a term for one specific statistical misuse, the prosecutor's fallacy, and Donnelly explains how it was exploited in the Sally Clark case. Definitely worth a look!

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The American Museum of Natural History
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10 Surprising Ways Senses Shape Perception
The American Museum of Natural History
The American Museum of Natural History

Every bit of information we know about the world we gathered with one of our five senses. But even with perfect pitch or 20/20 vision, our perceptions don’t always reflect an accurate picture of our surroundings. Our brain is constantly filling in gaps and taking shortcuts, which can result in some pretty wild illusions.

That’s the subject of “Our Senses: An Immersive Experience,” a new exhibition at the American Museum of Natural History in New York City. Mental Floss recently took a tour of the sensory funhouse to learn more about how the brain and the senses interact.

1. LIGHTING REVEALS HIDDEN IMAGES.

Woman and child looking at pictures on a wall

Under normal lighting, the walls of the first room of “Our Senses” look like abstract art. But when the lights change color, hidden illustrations are revealed. The three lights—blue, red, and green—used in the room activate the three cone cells in our eyes, and each color highlights a different set of animal illustrations, giving the viewers the impression of switching between three separate rooms while standing still.

2. CERTAIN SOUNDS TAKE PRIORITY ...

We can “hear” many different sounds at once, but we can only listen to a couple at a time. The AMNH exhibit demonstrates this with an audio collage of competing recordings. Our ears automatically pick out noises we’re conditioned to react to, like an ambulance siren or a baby’s cry. Other sounds, like individual voices and musical instruments, require more effort to detect.

3. ... AS DO CERTAIN IMAGES.

When looking at a painting, most people’s eyes are drawn to the same spots. The first things we look for in an image are human faces. So after staring at an artwork for five seconds, you may be able to say how many people are in it and what they look like, but would likely come up short when asked to list the inanimate object in the scene.

4. PAST IMAGES AFFECT PRESENT PERCEPTION.

Our senses often are more suggestible than we would like. Check out the video above. After seeing the first sequence of animal drawings, do you see a rat or a man’s face in the last image? The answer is likely a rat. Now watch the next round—after being shown pictures of faces, you might see a man’s face instead even though the final image hasn’t changed.

5. COLOR INFLUENCES TASTE ...

Every cooking show you’ve watched is right—presentation really is important. One look at something can dictate your expectations for how it should taste. Researchers have found that we perceive red food and drinks to taste sweeter and green food and drinks to taste less sweet regardless of chemical composition. Even the color of the cup we drink from can influence our perception of taste.

6. ... AND SO DOES SOUND

Sight isn’t the only sense that plays a part in how we taste. According to one study, listening to crunching noises while snacking on chips makes them taste fresher. Remember that trick before tossing out a bag of stale junk food.

7. BEING HYPER-FOCUSED HAS DRAWBACKS.

Have you ever been so focused on something that the world around you seemed to disappear? If you can’t recall the feeling, watch the video above. The instructions say to keep track of every time a ball is passed. If you’re totally absorbed, you may not notice anything peculiar, but watch it a second time without paying attention to anything in particular and you’ll see a person in a gorilla suit walk into the middle of the screen. The phenomenon that allows us to tune out big details like this is called selective attention. If you devote all your mental energy to one task, your brain puts up blinders that block out irrelevant information without you realizing it.

8. THINGS GET WEIRD WHEN SENSES CONTRADICT EACH OTHER.

Girl standing in optical illusion room.

The most mind-bending room in the "Our Senses" exhibit is practically empty. The illusion comes from the black grid pattern painted onto the white wall in such a way that straight planes appear to curve. The shapes tell our eyes we’re walking on uneven ground while our inner ear tells us the floor is stable. It’s like getting seasick in reverse: This conflicting sensory information can make us feel dizzy and even nauseous.

9. WE SEE SHADOWS THAT AREN’T THERE.

If our brains didn’t know how to adjust for lighting, we’d see every shadow as part of the object it falls on. But we can recognize that the half of a street that’s covered in shade isn’t actually darker in color than the half that sits in the sun. It’s a pretty useful adaptation—except when it’s hijacked for optical illusions. Look at the image above: The squares marked A and B are actually the same shade of gray. Because the pillar appears to cast a shadow over square B, our brain assumes it’s really lighter in color than what we’re shown.

10. WE SEE FACES EVERYWHERE.

The human brain is really good at recognizing human faces—so good it can make us see things that aren’t there. This is apparent in the Einstein hollow head illusion. When looking at the mold of Albert Einstein’s face straight on, the features appear to pop out rather than sink in. Our brain knows we’re looking at something similar to a human face, and it knows what human faces are shaped like, so it automatically corrects the image that it’s given.

All images courtesy of the American Museum of Natural History unless otherwise noted.

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Learn to Spot the Sneaky Psychological Tricks Restaurants Use
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iStock

While dining out, you may have noticed (but perhaps didn’t question) some unusual features—like prices missing dollar signs, or burgers served on plates that could accommodate a baby cow.

These aren’t just arbitrary culinary decisions, as the SciShow’s Hank Green explains in the video below. Restaurants use all kinds of psychological tricks to make you spend more money, ranging from eliminating currency symbols (this makes you think less about how much things cost) to plating meals on oversize dinnerware (it makes you eat more). As for the mouthwatering language used to describe food—that burger listed as a "delectable chargrilled extravagance," for example—studies show that these types of write-ups can increase sales by up to 27 percent.

Learn more psychological tricks used by restaurants (and how to avoid falling for them) by watching the video below. (Or, read our additional coverage on the subject.)

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