Tuesday, 21 September 2010

What do I want? Don't ask me: Choice blindness at the market stall

Imagine you sampled two jams, chose your favourite, and were then offered another taste of it before being asked to explain your preference. Would you notice that you'd been offered the wrong one, that you were actually tasting the jam you'd turned down? A new study conducted at a market stall by Lars Hall and colleagues found that even for tastes as dramatically different as spicy Cinnamon-Apple and bitter Grapefruit, fewer than 20 per cent of participants realised that they'd just tasted the jam they'd moments earlier turned down. Even after being told the truth, fewer than half said they'd suspected they'd been offered the wrong jam.

This striking lack of insight has been dubbed choice blindness. Before now, it had only been demonstrated for visual preferences, in relation to women's faces, in a lab environment. This new study finds the effect in the real world, and in the context of taste and smell (as well as choosing between pairs of jams, participants also used smell to choose between pairs of specialist teas including Pernod vs. Mango).

To test the choice blindness effect, researchers used sleight of hand and double-ended jam jars or tea jars with a divide in the middle. Each jar contained a different jam/tea option at each end. Participants were presented with a pair of jars and tasted/smelt a sample from each. Then, by surreptitiously inverting the jars, the researchers were able to offer participants a second taste/smell from what appeared to be the same jar they'd just selected as their favourite, but actually now contained the jam/tea choice that they'd turned down.

Remarkably, on trials in which the tea or jam had been swapped, participants were just as confident about their choice as they were on control trials. However, as you'd expect, participants more often detected that the jams/teas had been swapped when choosing between pairs that pilot work had established were more different from each other. Another twist was that some participants were told they could actually take away their favoured jam or tea as a reward. However, this made no difference to the rates at which they detected their choice had been swapped, thus undermining the idea that the choice blindness effect may have to do with a lack of motivation.

People's apparent lack of awareness about choices they themselves have just made not only raises awkward questions about the limits of conscious awareness, but surely also has real-world implications. The researchers put it this way: 'The fact that participants often fail to notice mismatches between a taste of Cinnamon-Apple and Grapefruit, or a smell of Mango and Pernod is a result that might cause more than a hiccup in the food industry, which is critically dependent on product discrimination and preference studies to further the trade.'

ResearchBlogging.orgHall 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, 117 (1), 54-61 PMID: 20637455

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.


skm said...

If the parameters of the experiment were changed to make the cost of a choice very dear, perhaps more subjects would notice the switch.

Spend 2000USD on a vacation package and get sent to the opposite side of the globe. See if you notice. otoh, make a reservation for a flight and you might not notice if the airline is swapped out when your itinerary shows up in your inbox.

I wonder if a surgeon would have choice blindness? a programmer who calls for a code review and has the code switched? someone on a dating site sending a message to a prospect and getting a reply back from a different account?

I went to the co-author's page to read more about this, and see that in the article they have a paragraph mentioning findings that are yet to be published about choice blindness in selecting laptops, and I'm really interested in hearing about those results. I know if I needed a certain component in a laptop and it was missing when I got the laptop that I'd be pissed when I tried to use it.

Back in school I recall people working on experiments to affect performance on recognition tasks, compare to experiments where the task is to test recall. I would expect the choice blindness results to alter if the blindness is in part due to poor recogniton task performance.

What if they alter the experiment to introduce interventions to improve performance on recognition tasks?

Modus Tollens said...

This sounds awfully similar to hemispatial neglect [http://en.wikipedia.org/wiki/Hemispatial_neglect], which is caused by the brain literally neglecting to process certain information. Once the chooser chooses a jam flavor, they no longer "need" to monitor the flavor for a single taste (I'd wager this effect disappears after several tastings over time). So they don't. This is different from the skm's examples of surgery, travel, etc. where post-choice monitoring is virtually certain.

Charles said...

Choice blindness = dopamine blindness/bias. Most of us are heavily influenced by dopamine-induced safety, approval, and esteem addictions. As a result, choices are often less than honest. Safety addicts fear making a wrong choice, approval addicts place gaining approval above their own opinions, esteem addicts care more about making the “smart” (esteem elevating) choice than telling the truth. In each case, scoring dopamine can become more important than the actual choice.

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