Gorillas that we missed: The deceptive powers of perception

Our visual system is great at doing what it's designed to do, which is to focus attention and stay on task. The way we do that is by avoiding distraction. Inattentional blindness - the failure to see someone in a gorilla suit - is really a byproduct of a system that works really well for what it does.

The Globe and Mail
May 24, 2010

Gorillas that we missed: The deceptive powers of perception
Ig Nobel Prize winners with a new book that explains just how fallible our minds really are talk with The Globe's Adriana Barton
Adriana Barton

Did you hear the one about the gorilla?

It's not a joke - it's psychology's famous "gorilla experiment," used in schools, corporations and anti-terrorism units to show how blind we can be when we're paying attention.

In the test, observers are asked to count basketball passes between two teams - half of them don't see a woman in a gorilla suit walking into the action and thumping her chest.

It illustrates the phenomenon of "inattentional blindness"- how people can miss events occurring directly in front of them. That, and many other illusions about our mental abilities can wreak havoc in our daily lives, according to psychologists Christopher Chabris and Daniel Simons, who won the 2005 Ig Nobel Prize in Psychology for the paper that detailed the experiment.

In their new book, The Invisible Gorilla And Other Ways Our Intuitions Deceive Us, they explain how fallible the mind is.

Bestselling books such as Malcolm Gladwell's Blink urge us to trust our intuition. How can gut feelings lead us astray?
Simons: There's a particular kind of intuition that's most dangerous and that's intuition about how your own mind works. Gut judgments can be useful when you're making decisions about things that wouldn't benefit from more data, for example, what kind of food you like - it's inherently emotional and personal. But many decisions, like which company to invest in, do benefit from more careful analysis. We would argue that the power of intuition has been somewhat oversold.

We're hearing a lot about neuroplasticity - how the brain can rewire itself. If that's true, why don't brain exercises work the way we hope?
Chabris: The fact that we can visualize changes in the brain with fancy new technology doesn't prove that exercising your brain with Soduku and crossword puzzles and video games is going to make you generally smarter. One thing it will do is make you better at all those things. But there's not much evidence that suggests those things will reduce your likelihood of developing Alzheimer's or even improve your ability to do everyday tasks.

Why do we miss what's in front of us and fail to remember things accurately?
Simons: Our visual system is great at doing what it's designed to do, which is to focus attention and stay on task. The way we do that is by avoiding distraction. Inattentional blindness - the failure to see someone in a gorilla suit - is really a byproduct of a system that works really well for what it does.

Chabris: As for memory, we think we are recording a lot more detail than we really are. It's really effortless to recall memories and I think that gives us the illusion that whatever comes in must be perfectly accurate.

What are the implications for the criminal justice system?
Chabris: It is a serious problem. The legal system kind of assumes that every memory is more accurate than it is and that people pay attention more than they do and that the more confident a witness is, the more likely [he or she is] to be truthful. One thing to do is to start to devalue the concept of eyewitness testimony.

Simons: In the cases of exonerated death-row inmates, most were based on the testimony of eyewitnesses that were flawed and most [inmates] were exonerated based on circumstantial evidence, such as DNA testing.

You cite Hillary Clinton's erroneous claim of landing in Bosnia under sniper fire as an example of a mental illusion. If false memories are as common as you suggest, how can we tell them from falsehoods?
Simons: There's the rub, of course. There are very few cases like Hillary's Bosnia landing, where there is documentary evidence of exactly what did happen, as opposed to people's memories of it.



The authors of The Invisible Gorilla, psychologists Christopher Chabris and Daniel Simons, caution against six distorted beliefs about our brains.

When focused on a task, we assume we won't miss things right in front us.

We trust our memories, but they are personal interpretations - not factual recordings - of past events.

We equate self-assurance with competence, in ourselves and others.

We mistake familiarity with subject matter for knowledge.

We draw conclusions about a root cause based on the order and relationship of events.

We think simple tricks can unleash untapped brainpower.

Adrianna Barton


Everyday myths and illusions

Tiger Woods' infidelities

Illusion of competence
A celebrity who sends text messages to multiple mistresses and thinks they'll never make headlines overestimates his ability to convince others to keep secrets, Dr. Chabris and Dr. Simons say.


Harvard fraud

Illusion of confidence
Accused of larceny and identity fraud for faking his way into Harvard and getting $45,000 (U.S.) in grants, Adam Wheeler of Delaware may be a modern-day Frank Abagnale, Jr., the imposter immortalized in the film Catch Me If You Can, the psychologists say. A con man ("confidence" man) takes advantage of others' blind faith in people who act as if they know what they're doing.


Gulf oil spill

Illusion of knowledge
BP executives who celebrated the project's safety record at the time of the explosions didn't understand the ongoing risks involved in drilling rigs, they say.


Bernie Madoff's Ponzi scheme

Illusion of Intuition
Dr. Chabris and Dr. Simons attribute this to the myth of intuition: Investors - and investigators - put such stock in Mr. Madoff's claim of having a "gut feel" for the market that his scheme wasn't exposed until he had bilked investors of billions.


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Risks: Bias: Illusory superiority (overestimate positive and underestimate negative traits), Heuristics: rule of thumb decision making that can sometimes result in catastrophe, Inattentional blindness: we fail to see what is right before us, Overconfidence effect, Unskilled and unaware bias (Dunning–Kruger effect), Your mind is tricked quite easily, Canada, 20100524 Gorillas that

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