30 August 2009

Where intuition misleads

Filed under: books, intuition — David Wood @ 7:24 pm

Some visions of the future provoke a three-letter reaction: Wow!

  • The audience is inspired by the vision.

Sometimes, however, the very same vision provokes, in different listeners, an alternative three-letter reaction: Yuk!

  • The audience is disgusted by the vision.

The “Yuk!” reaction is usually sparked by intuition – a internal feeling that the vision somehow violates nature, decency, or goodness.

I have a lot of respect for intuition, but I’m in no doubt that it often throws up wrong conclusions.

Optical illusions are a case in point. I’m sure we’ve all got our own favourite optical illusions.

I recently came across the striking example of the two pictures above.  As explained in a 2007 Scientific American article,

No, you have not had one grappa too many. These images of the Leaning Tower are actually identical, but the tower on the right looks more lopsided because the human visual system treats the two images as one scene. Our brains have learned that two tall objects in our view will usually rise at the same angle but converge toward the top—think of standing at the base of neighboring skyscrapers. Because these towers are parallel, they do not converge, so the visual system thinks they must be rising at different angles

And here’s another really stunning case – created by Edward H. Adelson of MIT:

Almost unbelievably, the squares marked A and B are the same shade of gray.  (Click here for the proof.)  How badly our intuition leads us astray in such examples!

I was recently reminded of some more serious limitations of intuition by the following extracts from the opening chapter of Good and Real by Gary Drescher:

To view the universe and its contents – including us – as machines strikes many people as implausibly and unpleasantly cold, a peculiar denial of our true nature…

Distinguishing what is true from what merely feels true is important to our understanding of anything.

Our culture’s pervasive skepticism about reason and mechanism is amply proclaimed in our popular entertainment.  In Star Wars, a mentor instructs his blindfolded student to trust his true feelings, his intuition, as a substitute for the missing sensory information.  In the film’s mystical fantasy world, that advice turns out to be sound, which makes for fun storytelling.

But reality is quite different.  In the early days of aviation, for example, pilots flying inside clouds would regularly lose control of their aircraft and crash.  Unable to see the ground or the sky, the pilots literally could not tell which way was up.  They relied on their sense of balance and their overall spatial intuition.  But as an airplane banks, its flight path curves, and centrifugal effects keep the apparent downward direction pointing straight to the floor of the airplane.  To its occupant, the cloud-enshrouded airplane still feels level even as it banks and dives more steeply.

Today, safe flight inside clouds is possible using gyroscopic instruments that report the airplane’s orientation without being misled by centrifugal effects.  But the pilot’s spatial intuition is still active, and often contradicts the instruments.  Piliots are explicitly, emphatically trained to trust the instruments and ignore intuition – precisely the opposite of the Star Wars advice – and those who fail to do so often perish.

In fact, the pilot’s spatial intuition is itself based on information from mechanical sensors in the pilot’s body – sensors that provide visual, tactile, proprioceptive, and vestibular cues about spatial orientation.  Ordinarily, those sensors work well: without them, we’d be unable even to walk.  But those particular sensors are inadequate when flying inside clouds – there, we need gyroscopes.

Drescher draws the following conclusion:

The plight of the pilot illustrates a crucial principle: rationally understanding how our feelings and intuitions are mechanically implemented can help us distinguish when our intuitions are trustworthy and useful and when, on the other hand, they mislead us – sometimes calamitously.

It provides a great lead-in to the rest of Dreschler’s book:

The following chapters look into the underpinnings of some of our deepest intuitions – about consciousness, choice, right and wrong, the passage of time, and other matters – in an effort to draw a similar distinction.

I’m still at an early stage in reading the book, so I can’t yet say whether I agree with Dreschler’s more substantial proposals.  But I do think that the vivid example of cloud-enshrouded pilots will stick in my mind.


  1. I also have a lot of respect for intuition, but, as you say, it can throw up the wrong conclusions. One of the most important (and difficult) skills to learn, is that of knowing when to trust your intuition.

    Working with other smart people helps. While you can do something yourself because ‘it feels right’, you cannot expect other people to act just on your say so. Being able to work out the reasons behind your intuition and then articulate them is an important part of working in or leading a team.

    It’s also useful to distinguish between learned and inherent intuition. Inherent intuition goes badly wrong when taken out of its evolutionary context. The aviation example applies here: we did not evolve to fly in clouds, so any intuitive behaviour is likely to be wrong.

    Learned intuition is much more reliable. By learned intuition I mean the intuition gained by years of practice, for example the intuition of a chess player, or a mathematician, or how a tennis player intuitively positions themselves on the court to take the next shot. I regard this sort of intuition as a transfer of knowledge from the conscious to the unconscious mind. I find it interesting that becoming an expert in a field involves transfering much of the knowledge of a subject into the unconscious mind and thus losing the ability to explain the reasons behind ones decisions.

    Comment by Martin Budden — 31 August 2009 @ 8:43 pm

    • Hi Martin,

      While you can do something yourself because ‘it feels right’, you cannot expect other people to act just on your say so. Being able to work out the reasons behind your intuition and then articulate them is an important part of working in or leading a team…

      An aside: It’s my observation that people who are successful often don’t know which of their habits and skills are really responsible for their success, and they get it wrong when they try to articulate their own “recipes for success” (eg in autobiographical books). It’s all part of the wider problem of understanding which habits and skills really do increase the chances of personal and societal success. (After all, correlation doesn’t imply causation; just because a manager did X and became successful, it doesn’t mean that doing X is the cause of the success.)

      …intuition gained by years of practice, for example the intuition of a chess player, or a mathematician, or how a tennis player intuitively positions themselves on the court to take the next shot…

      The mention of tennis reminds me of my experience, earlier today, with holding a golf club. I’ve got an ingrained “intuition” about how I should hold a golf club. It “feels right” in a certain way. But my golf coach is able to point out how, when I hold the club that way, my shots typically veer off towards the left. If I force myself to hold the club in a different way – in a way that (currently) “feels wrong” to me, the shots tend to go straight. So I’ve got to unlearn an unhelpful intuition, and replace it with a more helpful one.

      That brings me back to my reason for blogging on this topic. The question of how to hold a golf club has more serious analogues with questions of which of our personal and societal intuitions remain good guides for life in the midst of our current technological and cultural upheavals – and which of these intuitions urgently need to be unlearnt.

      // David W.

      Comment by David Wood — 31 August 2009 @ 10:30 pm

  2. Your golf club experience is illustrative: human beings did not evolve to play golf, so any inherent intuition about how to hold a golf club is likely to be wrong. Once you have been shown how to hold the club properly and practice this sufficiently you will intuitively hold the club correctly. But your new learned intuition is not necessarily transferable – if you take up cricket or tennis or croquet you will need to learn a new grip. Some of your golfing skills (eg following through) will be transferable to other sports. When learning a new skill it’s always advisable to get some coaching – otherwise we form new bad habits which are hard to break.

    As for which intuitions remain good guides in “our current technological and cultural upheavals”, well, I find that phrase a bit too vague to offer any conclusions. I will observe that human beings did evolve to socialise, so our intuitions about how we interact with our fellow human beings are probably good, even if those interactions are through an electronic medium.

    Comment by Martin Budden — 1 September 2009 @ 8:02 pm

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