Do you know what you like?

Imagine you are in a study and you are asked to pick which of two faces you find more attractive. After you make your pick, you explain why you liked the one you did. Maybe you like blonds. Perhaps you prefer strong, bold features. Everyone can give reasons for why they found one person more attractive than another, but those reasons might be entirely after-the-fact rationalizations rather than the real reasons. My favorite study of the past few years did just that. Lars Hall and Petter Johansson asked people to pick which of two portraits they found most attractive. They then handed people their selected picture and asked them to justify their choice. On some critical trials, though, they used sleight of hand to reveal a sleight of mind: They handed people the portrait that they had NOT picked — the one that they had found less attractive. Not only did people fail to spot the switch (change blindness), they gave the same sort of justification that they would have given for the picture they did select. They looked at the picture they had been handed and came up with reasons why they preferred it. Had you picked a brunette and been handed a blond, you would justify your selection by saying you prefer blonds!

Watch this short YouTube video of their study, filmed by the BBC:

Hall and Johansson call this effect “choice blindness,” and they also show that people have the wrong intuitions about what they will notice: Most people are convinced that they would notice when handed the wrong picture even though they don’t. After all, we must have chosen that face for a reason! Their discover of choice blindness was published in Science in 2005. It was also their first scientific publication — not a bad start to their careers!

Now they are back with a new paper in-press in Cognition entitled “Magic at the marketplace: Choice blindness for the taste of jam and the smell of tea.” In the new study, they set up a taste test at a local market and asked shoppers to sample tea or jam.  Even with radically different flavors (cinnamon-apple replaced by bitter grapefruit), more than half missed the change and justified their selection of the wrong item!  As for judgments of attractiveness, such emotional taste preferences do not lend themselves to rational, deliberative explanation.  We have preferences,  but we don’t necessarily know the reasons for them, and when forced to explain, we can justify liking things that we actually don’t like.  As for many judgments about how our own minds work, we get it wrong.  Our intuitions might get it right for emotional preferences, but our meta-intuition (intuitions about our intuitions) get it wrong.

Their new paper is available as a pdf

Sources Cited

Johansson P, Hall L, Sikström S, & Olsson A (2005). Failure to detect mismatches between intention and outcome in a simple decision task. Science (New York, N.Y.), 310 (5745), 116-9 PMID: 16210542

Hall L, Johansson P, Tärning B, Sikström S, & Deutgen T (2010). Magic at the marketplace: Choice blindness for the taste of jam and the smell of tea. Cognition PMID: 20637455

1 comment to Do you know what you like?

  • BO

    I don’t quite understand what the change blindness has to do in the context of selective attention. Does the view of the attractive face or the taste of the better jam let us focus on the good aspects of the thing (face(jam) and we “blind out” the other ones? And what’s the point of it?

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