Prevalence-induced concept change in human judgment

“Prevalence-induced concept change in human judgment”, Science, 29th June 2018. (Free abstract, free methods and data, article $ paywalled).

If something is commonly encountered, then we tend to narrow our criteria for judging its presence. If that same something then becomes rarer, but we ‘think’ it should still be encountered, then we will tend to widen our criteria for judging its presence. It then follows that, as the world makes extraordinary progress on many fronts, the criteria for judging what is ‘good news’ shrinks and the criteria for ‘bad news’ expands.

The paper has polished writing and stimulating ideas, but crumbles when one looks at the supplementary material on its sample-sizes and methods. As usual, a so-called ‘scientific’ study in Psychology is found to rest on ridiculously tiny sample-sizes drawn from adolescents wholly unrepresentative of the general population. In this case, “Participants were 22 students at Harvard University” in the first study, rising to just over 40 students in one of the later sub-studies. Such studies may say something about sleep-deprived, malnourished, hungover and hormone-addled adolescents, who are drawn from a particular economic and high-IQ niche and embedded in a particularly stimulating institution. They say little about the general population. I had heard that Psychology was supposed to be reforming its methodologies after its various existential crises, but no… here we see Science and Harvard waving through a ‘business as usual’ study as if nothing had changed.

That said, there could be some worthwhile extrapolation made from this study to journalists as-a-class, and thus it seems worth noting. Because journalists and their individual perceptions and jaundiced views, as well the deeper structures-of-feeling embedded in news-room workflows, are important to consider in understanding why we are constantly subjected to daily tidal-waves of ‘bad news’.