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Brotherzed comments on The Affect Heuristic - Less Wrong

37 Post author: Eliezer_Yudkowsky 27 November 2007 07:58AM

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Comment author: Brotherzed 21 November 2014 06:14:13PM *  1 point [-]

The way you're summarizing the "disease" study mangles what was described in the abstract, even though the abstract makes your own point. I haven't checked the rest. I went digging for the abstract:

Participants assessed the riskiness of 11 well-known causes of death. Each participant was presented with an estimation of the number of deaths in the population due to that particular cause. The estimates were obtained from a previous study of naive participants' intuitive estimations. For instance, based on the result of the previous study, the number of deaths due to cancer was presented as: ‘2,414 out of 10,000’, ‘1,286 out of 10,000’, ‘24.14 out of 100’ and ‘12.86 out of 100’. The estimates of deaths were presented in analogous ways for the remaining ten causes of death. It was hypothesized that the judged degree of riskiness is affected by the number of deaths, irrespective of the total possible number (such as 10,000 or 100). Results from Experiment 1 were consistent with this prediction. Participants rated cancer as riskier when it was described as ‘kills 1,286 out of 10,000 people’ than as ‘kills 24.14 out of 100 people’, and similar results were observed regarding the remaining 10 causes of death. Experiment 2 replicated this trend. Implications for risk communications are discussed. © 1997 John Wiley & Sons, Ltd.

The way you described it --

Then how about this? Yamagishi (1997) showed that 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. Apparently the mental image of a thousand dead bodies is much more alarming, compared to a single person who's more likely to survive than not.

Crucially, your verbiage as-is provides Group A with a 12% total population mortality rate, and Group B with a 24% case fatality rate, and those are incommensurable. I'm assuming you meant to say the information was presented to two separate groups, maybe too generously there too. The original study very explicitly specifies mortality rate for both figures. I.E. 24.14 out of 100 to be fatal for the whole population (for a cancer, and not expressed as a % - different priming effects on some).

If you got that past all of us, I think it shows there are chinks in our armor as well. I wouldn't deny that the affect heuristic is real, but the way you present the information doesn't pass my smell test.