Today's post, The Affect Heuristic was originally published on 27 November 2007. A summary (taken from the LW wiki):


Positive and negative emotional impressions exert a greater effect on many decisions than does rational analysis.

Discuss the post here (rather than in the comments to the original post).

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2 comments, sorted by Click to highlight new comments since: Today at 5:10 AM

(Hello, All! This is pretty much my first post (excluding "did the survey") on here. Looking forward to some interesting discussions)

It seems to me that the examples (ie "subjects judged a disease as more dangerous when it was described as killing 1,286 people out of every 10,000, versus a disease that was 24.14% likely to be fatal) were presented here in a context conducive to thinking about them rationally. I rather doubt they were presented similarly to the test subjects. Here are two different ways of presenting this information:

METHOD 1 Disease A kills 1,286 people out of every 10,000. Disease B is 24.14% likely to be fatal . All other things being equal, which is more dangerous?

METHOD 2 Emma contracted bloxy pox at 8 years of age. 10,000 children contract bloxy pox every year. Emma was one of the 1,286 who do not survive this fatal disease. She died after a painful 3 month struggle. But bloxy pox is not the only fatal childhood disease: Crompularia is 24.14% likely to be fatal....etc, etc.....How would you feel if your child contracted bloxy pox? What would you do? Do you think we should fund money to cure childhood illnesses? Which disease do you think is most dangerous?

It seems that because the article presents the information to US in a rational context (and we therefore think about it rationally) we tend to assume that the experiments were presented similarly, such as in Method 1 above. This leads to many comments to the sequence along the lines of "People Are Stupid!".

I would assume that instead the information was presented in a manner that put people into a more intuitive mindset. I've not actually read the source material to know for sure, though. So if you have, please let me know if I am correct in this assumption.

I think the point these articles are trying to make is not that people CAN'T do probability calculations (which many commenters seemed to joke about), but rather that we, as humans, DON'T do a lot of probability calculations in our default/ intuitive state. I feel this is an important distinction to make, and one which many commenters seemed to ignore.

Actually, our probability calculations might be substantially ignored when making our decisions.

Participants (health professionals and consumers) understood natural frequencies better than percentages...In studies of alternative formats for presenting risk reductions of interventions, and compared with [Absolute Risk Reduction], [Relative Risk Reduction] had little or no difference in understanding but was perceived to be larger and more persuasive

People got similar understanding from those formats, but chose differently.

...Compared with [Number Needed to Treat], RRR was better understood...was perceived to be larger and was more persuasive

Here people were sensible, at least.

Compared with NNT, ARR was better understood...was perceived to be larger...There was little or no difference for persuasiveness.

People were equally persuaded by those formats, but had different understanding as to what was going on.

Overall there were no differences between health professionals and consumers.


Spin it here!