The Invisible Gorilla.

And other ways our intuition deceives us.

by Christoper Chabris and Daniel Simons.

Amazon review: 4 stars.

Christoper Chabris and Daniel Simons wonderful book ''The invisible Gorilla'' is all about how our intuition deceives us. The book has its name from the authors ''basketball experiment'', where people fail to recognize a Gorilla in their midst.
Indeed, our brains routinely plays tricks on us! Sure, we may think we experience and understand the world around us. But actually, often, we can miss the gorilla standing right in front of us! When we assume there should be no gorilla in front of us, we tend not to see any gorillas, even if they are there...
The authors gorilla experiment is a brilliant illustration that looking is not necessarily seeing. But there are a myriad of other illusions out there. The ''gorillas'' are lurking everywhere.

Our brains does indeed create ''change blindness'', ''the illusion of confidence'', ''the illusion of knowledge'', ''the illusion of always being in control'' etc. Certainly, conditioning, priming etc. tells us that we are not just objective observers of the world. Far from it actually: We are hardwired to edit our perceptions and memories, to misinterpret evidence and jump to conclusions. And as information are hurled at us from all sides in todays world, the book's key message is that we think our mental abilities and capacities are greater than they really are. Important stuff. And brilliantly presented in this book.

The ''Invisible Gorilla'' illusion (''The monkey business illusion''):

The purpose of attention is to focus our minds. Focused attention ''allows us to avoid distraction and use our limited resources more effectively; We don't want to be distracted by everything else around us.''

Change blindness:

Imagine that you are strolling along, and you see a man holding a map and looking lost. The man ask you for directions, and as you are pointing to the map, a couple carrying a wodden door rudely cuts in between you and the lost man.
Once they pass, you finish giving instructions, but would you have noticed if the lost man was replaced in all the commotion?
50 percent in the original experiment did not notice any change...

The ''Door'' Study (change blindness):

Later experiments show that people do notice if you change a man into a woman, or when you change the race. And people are more likely to notice a change to the identity of a person who is a member og their own social group. But most often changes go undetected...

The illusion of confidence:

In chess there is an objective public rating system that provides accurate, precise information about a players ''strength'' relative to other players. A master player has a rating of 2200 or above, while the average rating (US. chess federation 1998) is 1337. Ratings are set and adjusted so that over a long series of games, the player with the highest rating is the likely winner of game. If the difference in rating is big enough, the one with the lowest rating will never win. A difference of 200 points will make it unlikely that the weaker player will win, a difference of 400 points will make it almost impossible.
When chess players are asked about their current rating 75 percent believe that they are underrated.... On average players thought that they were 99 points underrated. Meaning that if they came up against a player with their own rating they would win hands down....

Chabris and Simons takes this as one example of the illusion of confidence. Which probably applies to all areas of human experience. Everyone, unless they are clinical depressed, think they are little better than the rest. 63 percent of Americans consider themselves to be above average in intelligence [p. 91]. 77 percent of Swedish college students thought that they were in the top 50 concerning driving safety.
Most people consider themselves to be above average in attractiveness. Many think they have terrific leadership skills. And sure enough, most of us have experienced an oblivious, incompetent office manager... There are even incompetent doctors out there :-) People who graduate last in their medical school classes are still doctors, and probably think they are pretty good ones.
Confidence is a big thing (even though it is not one of the traits that are usually compiled, i.e. neuroticism, extraversion. openness to experience, agreebleness and conscientiousness, See: Big Five Personality Traits).

Group leadership is determined largely by confidence. A confident person speak tend to speak first in a group - and the group tend to follow who has spoken first. Conformity is the other side of the coin here.

Confidence and Conformity:

See Soloman Aschs tests on conformity and dominance:

More group pressure - and conformity after a while:

Better still is John Darley and Bibb Latane's smoke room experiment from the late 1960s. Here a student is asked to complete a questionnaire about campus life. To do this, the student is placed in a room with other students, who where really stooges of the experimenters. Severel minutes into the experiment, a duct in the wall begins spewing out smoke, as though there is a fire in the building. The stooges pay no attention to this and just keep filling out their forms. Seeing this most students do nothing... there might be a moments hesitation and confusion, seeing the others calms them down, and they also do nothing. Even though a fire might be raging through the building and putting their lives at risk.
When a student was placed alone in the room, smoke would immediately prompt them to run out, take action or report the fire.

The smoked filled room:

Wonderful stuff. Apparently it is better to die that to stand out from the crowd?
According to Robin Dunbar (in the book ''Evolutionary psychology''): '' There must be some counter balancing benefit, otherwise evolution should select heavily against such conformity behaviour. According to dunbar: By doing what the majority are doing, we average a great number of individual learning experiences and so arrive at a behaviour that has been tested and proven successful. Allowing the prevailing culture to determine our behaviour can therefore be a smart thing to do ...''

In english the ''con'' part of ''con man'', ''con artist'' and ''con game'' is short for confidence. As humans believe that confidence predict ability.....
Unfortunately this is not always so. Confident people are no more accurate the less confident people. Confidence is also unrelated to intelligence. Confidence is a quality that varies from one person to the next but has relatively little to do with ones underlying knowledge or mental ability.
''In medicine, the confidence cycle is sel-perpetuating. Doctors learn to speak with confidence as part of their medical training (of course there may also be a tendency for inherently confident people to become doctors). Then patients, mistaking confidence for competence, treat doctors more as priests with divine insight than as people who might not know as much as they profess to. This adulation in turn reinforces the behaviours of doctors, leading them to be more confident.''
''A number of studies show that patients are more likely to trust and confide in doctors who are dressed formally and wear a white lab coat than those who dress more casually. Yet, the worst doctor is able to put on a lab coat, just as the best doctor, so what doctors wear should have no bearing on our estimation of their abilities....''

When dealing with people we know very well, we can judge whether their confidence is high or low for them. With knowledge of the range of confidence someone exhibits, you can use confidence as a reasonable predictor of that persons knowledge in a given situation.
The problem is that confidence is also a personality trait. So confidence as a measure of ability becomes a potentially catastrophic everyday illusion, when we deal with people we hardly know.

Illusion of knowledge:

There are no illusions of blindness, amnesia, idiocy and and cluelessness...
''Instead, everyday illusions tells us that we perceive and remember more than we do. That we're above average, and that we know more about the future than is justified. That we have a deep understanding of what a project will entail, when all we have is a rough and optimistic guess based on shallow familiarity.''
E.g. The Sydney Opera house was forecast in 1960 to cost 7 million Australian dollars. By the time it was finished it had cost 102 million Australian dollars. -- It always takes longer than you expect.

Indeed, we would all be better off if we followed Einsteins word: ''Everything should be as simple as possible, but not simpler'':
Tim Roberts won the $25.000 top prize in the 2008 edition of the computer programming tournament called the Top coder Open. He had six hours to write a program that met a set of written specification. Unlike his competitors Roberts spent the first hour studying the specs and asking questions . Only after verifying that he completely understood the challenge did he start to code. The time he spent escaping the illusion of knowledge was an investment that paid off handsomely in the end.

And obviously we should actually understand, not just see pretty pictures, and think we understand:
Brain Porn ''the colorful images of blobs of activity on brain scans that can seduce us to into thinking we have learned more about the brain, than we actually have.''.
In one study it was found that ''.... Subjects who read the text with the brain porn thought that the article was significantly better written and made more sense...The kicker is that none of the fictious studies actually made any sense. - they all described dubious claims that were not at all improved by the decorative brain scans.''

And we should remember that our memories are not that good: ''What is stored in memory is not an exact replica of reality; but a re-creation of it. We cannot play back our memories like a DVD - each time we recall a memory, we integrate whatever details we do remember with our expectation for what we should remember.''
Continuity errors are common in movies (e.g. see Star Wars continuity problems). Its has to do with how movies are made. Rarely are they shot in sequence, and in real time from start to finish. Each scene is filmed from many different angles, and the final film is spliced together in an editing room.

Spotting patterns and being in control:

Pattern perception is central to our lives, and skill in many professions is based almost entirely on the ability to spot patterns.
Actually, evolution has built our minds to crave causation.
Stories, sport events, grap and hold peoples attention because the outcome is in doubt.
Unfortunately, at times we perceive patterns where none exist. And we misperceive them where they do exist.
Sometimes we don't see the causation that is right there in front of us.


Sure, we all have tremendous potential to learn new skills and to improve our abilities. The plasticity of the adult brain - its ability to change its structure in response to training, injury etc. - is great indeed.
We can learn new things and change how we behave in the world

But, we might not have as much control over why we change behaviours, and when we do it, as we would like to think...
Surely, other people can't put stuff into our minds and change our behaviour without us knowing...?
Guess again ! :-)

In one simple experiment all it took (to change peoples behaviour) was letting them count money (giving them the illusion of having resources).
Strangely, counting money was enough to unconsciously change how they thought about hunger, helpfulness and handling of pain later on...

See more at Chabris and Simons page The Invisible Gorilla.

Amazon: [1], [2].
Posterous: [3].

From: Simon Laub
Newsgroups: sci.psychology.misc,alt.psychology
Sent: Sunday, February 20, 2011 6:44 PM
Subject: The invisible gorilla and other brilliant illusions


Simon Laub

About | Site Index | Post Index | Recent psychology book reviews | Connections | Future Minds | Contact Info
© February 2011 Simon Laub - -
Original page design - February 19th 2011. Simon Laub - Aarhus, Denmark, Europe.