Sarah Lichtenstein

Who they are

The vault holds no biography for her and no confirmed current post, so none is claimed here. What can be said is limited to the work. She appears as first author of a study that has become a reference point for every later discussion of how people judge risks, and Kahneman names her, with Slovic and Fischhoff, in the chapter of Thinking, Fast and Slow where he sets out the causes-of-death results.

The 1978 paper is a team product. Slovic and Fischhoff are better known to general readers. Authorship order here matters for credit: Lichtenstein is the first author, and a citation that says only Slovic omits her.

Key papers

Lichtenstein, S., Slovic, P., Fischhoff, B., Layman, M., & Combs, B. (1978). Judged frequency of lethal events. Journal of Experimental Psychology: Human Learning and Memory, 4(6), 551-578.

According to the abstract, the authors ran a series of experiments on how people estimate how often various causes of death occur. The estimates were highly consistent but systematically distorted in two ways. People overestimated small frequencies and underestimated large ones. And at any given actual frequency, they exaggerated some causes of death and understated others. The authors traced the biases to factors including disproportionate exposure, memorability and imaginability. Participants could not correct for these biases even when told to avoid them. The paper compares its findings with earlier laboratory studies, suggests ways to improve frequency judgements, and discusses what the results imply for managing societal hazards.

Key ideas

The study is the main empirical anchor for the claim that media-prone, memorable causes of death are overestimated. Kahneman reproduces its results in Thinking, Fast and Slow. Strokes cause almost twice as many deaths as all accidents combined, but 80 per cent of respondents judged accidental death to be more likely. Tornadoes were seen as more frequent killers than asthma, although asthma causes 20 times more deaths. Death by lightning was judged less likely than death from botulism even though it is 52 times more frequent. Death by disease is 18 times as likely as accidental death, but the two were judged about equally likely. Death by accidents was judged to be more than 300 times more likely than death by diabetes, but the true ratio is 1 to 4.

Those figures come from Kahneman's account, and the vault has not checked them against the 1978 paper. What the abstract does support is the pattern: consistent estimates, systematic distortion, and an inability to correct it on request.

The result has since been read in more than one way. Kahneman presents it as availability, in which memorable causes are exaggerated because examples of them come to mind readily. A 2012 study by Thorsten Pachur, Ralph Hertwig and Florian Steinmann tested availability against the affect heuristic and found that availability from recall, based on direct experience of risks within a person's social network, matched judgements best, while media exposure played a minor role. The 1978 authors named memorability and exposure as sources of distortion, and the later work asks where the exposure comes from.

For marketers, the lesson is to be careful about which exposure counts. The 1978 paper shows that frequency estimates are distorted. It does not by itself show that a news story changes a purchase.

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