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Written by Neel Shah

Edited by Andrew Neff

August 2019

The crowd within

How ‘sleeping on it’ helps you make better decisions

Wisdom of the crowd

Picture this. You’re in the chair on Who Wants to Be a Millionaire. It’s the $1 million question and you have no idea what the answer is but its something you should know. You ask the audience. 70% of the audience say it’s answer A. Do you trust them?

Countless studies in psychology have revealed the effect of the wisdom of the crowd. Galton (1907) when looking at how people have guessed the weight of a prize-winning ox, found that the error of the average response was much closer to the real weight than the average error of any individual estimate. Steyvers et al. (2009) found a similar effect when asking participants to re-order a series of historical events individually and then with group feedback. The idea of the wisdom of the crowds has even been used to support the identification of web-spam and phishing websites (Moore and Clayton, 2009). In the sports betting and financial trading world, the wisdom of the crowd effect creates a powerful market force that can make these markets incredibly efficient and usually fairly accurate.

But what about the wisdom of ourselves? Could asking for a person's guess on multiple occasions, then averaging their responses, be better than their individual guesses? Most research has assumed that taking two guesses from one person is a futile exercise. After all, if an individual guess is prone to error, then two guesses from the same person would only amplify that error. However, Vul and Pashler (2008) argue that as long as the two estimates from one person have a degree of independence, then they might be more accurate. 


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They recruited over 400 participants and asked them 8 questions designed to test their real-world knowledge, taken from the CIA’s World Factbook from 2007. The participants were asked to guess the correct answer. Half of them were then asked to make a second answer to their questions immediately after finishing their questionnaire. The other half were asked to make a second guess 3 weeks later. 


If asked immediately, the accuracy of the participant's two answers was 10% higher than comparing and combining their first answer with a second opinion from someone else. If asked after 3 weeks, the accuracy went up to 33%!

This suggests that the common conception of our first guess being the best guess can often be misplaced. Our second-guesses can contribute additional information, especially with a time delay because it makes the estimates fairly independent from one another.

The ancient wisdom of ‘sleeping on it’ seems to have some relevance here. If given a second opportunity to estimate something, we are generally more accurate, especially given a second chance where we may not remember or be as easily influenced by the first time. 


In practical terms, it’s an interesting take on the conventional wisdom of the crowd's theory that shows we can overcome some of our own cognitive biases and trust a second opinion, even if it is our own. 


One criticism that could be leveled is the mundane nature of the task. Decision making is often made under varying degrees of pressure and time constraints. Being asked trivial questions literally about trivia means its harder to generalize these findings to how accurate we would be in real-world situations. But still, the next time you’re thinking about second guessing yourself, you never know. You might end up making a better decision!



  1. Galton, F. (1907). Vox populi. Nature, 75, 450–451

  2. Moore, T., and Clayton, R. 2008. Evaluating the wisdom of crowds in assessing phishing websites. In Financial Cryptography and Data Security. Springer. 16–30.

  3. Steyvers, M.; Miller, B.; Hemmer, P.; and Lee, M. D. 2009. The wisdom of crowds in the recollection of order information. In Advances in neural information processing systems, 1785–1793

  4. Vul, Edward, and Harold Pashler. "Measuring the crowd within: Probabilistic representations within individuals." Psychological Science 19.7 (2008): 645-647.


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Skeptical Science

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5% of our annual proceeds are donated to the John Templeton Foundation.

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