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Can Social Dynamics Explain Conjunction Fallacy Experimental Results?

by curi1 min read5th Aug 20208 comments


FallaciesSocial & Cultural DynamicsRationality

Is there any conjunction fallacy research which addresses the alternative hypothesis that the observed results are mainly due to social dynamics?

Most people spend most of their time thinking in terms of gaining or losing social status, not in terms of reason. They care more about their place in social status hierarchies than about logic. They have strategies for dealing with communication that have more to do with getting along with people than with getting questions technically right. They look for the social meaning in communications. E.g. people normally try to give – and expect to receive – useful, relevant, reasonable info that is safe to make socially normal assumptions about.

Suppose you knew Linda in college. A decade later, you run into another college friend, John, who still knows Linda. You ask what she’s up to. John says Linda is a bank teller, doesn’t give additional info, and changes the subject. You take this to mean that there isn’t more positive info. You and John both see activism positively and know that activism was one of the main ways Linda stood out. This conversation suggests to you that she stopped doing activism. Omitting info isn’t neutral in real world conversations. People mentally model the people they speak with and consider why the person said and omitted things.

In Bayesian terms, you got two pieces of info from John’s statement. Roughly: 1) Linda is a bank teller. 2) John thinks that Linda being a bank teller is key info to provide and chose not to provide other info. That second piece of info can affect people’s answers in psychology research.

So, is there any research which rules out social dynamics explanations for conjunction fallacy experimental results?

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There's some recent research by Kevin Dorst and Matthew Mandelkern into the idea that people fall for the conjunction fallacy because they are so often trying to strike a balance between being correct and being informative.

Roughly, the idea is that guessing "Linda is an activist and a bank teller" is so informative, it's sometimes more preferable as a guess than just guessing that Linda is a bank teller. Giving not just true but informative guesses is such an ingrained habit that it's hard to stop and select the option most likely to be true.

You can download their paper here: https://philpapers.org/rec/DORGG or read a blog post by Kevin Dorst here: https://www.kevindorst.com/stranger_apologies/the-conjunction-fallacy-take-a-guess

The social dynamics that you point to in your John-Linda anecdote seem to depend on the fact that John knows what happened with Linda. This suggests that these social dynamics would not apply to questions about the future, where the question was coming from someone who couldn't know what was going to happen.

Some studies have looked for the conjunction fallacy in predictions about the future, and they've found it there too. One example which was mentioned in the post that you linked is the forecast about a breakdown of US-Soviet relations. Here's a more detailed description of the study from a an earlier post in that sequence:

Another experiment from Tversky and Kahneman (1983) was conducted at the Second International Congress on Forecasting in July of 1982.  The experimental subjects were 115 professional analysts, employed by industry, universities, or research institutes.  Two different experimental groups were respectively asked to rate the probability of two different statements, each group seeing only one statement:
1. "A complete suspension of diplomatic relations between the USA and the Soviet Union, sometime in 1983."
2. "A Russian invasion of Poland, and a complete suspension of diplomatic relations between the USA and the Soviet Union, sometime in 1983."
Estimates of probability were low for both statements, but significantly lower for the first group than the second (p < .01 by Mann-Whitney).  Since each experimental group only saw one statement, there is no possibility that the first group interpreted (1) to mean "suspension but no invasion".