10 Illuminating Examples of Behavioral Science
Introduction
Behavioral science studies how people actually decide, as opposed to how an idealised rational agent would. The ten effects below are among the field's best-known findings; each is described with the study that first demonstrated it, so you can go back to the source or adapt the paradigm for your own experiment.
Examples of Behavioral Science
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The Anchoring Effect
When making estimates, people rely heavily on the first piece of information they encounter (the "anchor") and adjust insufficiently from it. In the original demonstration, Tversky and Kahneman (1974) spun a wheel of fortune before asking participants to estimate the percentage of African countries in the United Nations; higher numbers on the wheel produced higher estimates. Initial list prices shape how consumers judge later discounts in the same way.
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Loss Aversion
People weigh losses more heavily than equivalent gains. In prospect theory (Kahneman & Tversky, 1979) the value function is steeper for losses, and estimates of the loss-aversion coefficient typically fall around 2: a loss of $10 feels roughly as bad as a gain of $20 feels good.
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The Endowment Effect
People assign a higher value to things merely because they own them. In the classic mug experiment (Kahneman, Knetsch & Thaler, 1990), participants who had been given a mug demanded about twice as much to sell it as other participants were willing to pay to buy it.
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Confirmation Bias
People seek out, interpret and remember information in ways that confirm what they already believe (Wason, 1960; Nickerson, 1998). The effect survives even when participants are explicitly asked to be objective.
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Reciprocity Principle
When someone does something for us, we feel obliged to return the favour. Regan (1971) showed that participants who received an unrequested soft drink from a confederate later bought twice as many raffle tickets from him; free samples and trials work on the same principle.
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Social Proof
When unsure how to act, people look to what others are doing. In Asch's (1951) line-judgment studies, about a third of responses conformed to an obviously wrong majority; today the same mechanism shows up in the weight we give to star ratings and reviews.
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The Halo Effect
A positive impression on one dimension colours judgments on unrelated dimensions. Thorndike (1920) first described it in officers rating their soldiers; Dion, Berscheid and Walster (1972) showed that attractive people are assumed to be kinder and more competent.
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Cognitive Dissonance
Holding two inconsistent cognitions is uncomfortable, and people change attitudes to reduce the tension. Festinger and Carlsmith (1959) paid participants $1 or $20 to tell someone a boring task was fun; those paid only $1 later rated the task as more enjoyable, because they had less external justification for the lie.
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The Scarcity Principle
Items in short supply are perceived as more valuable. Worchel, Lee and Adewole (1975) found that cookies from a jar containing two were rated as more desirable than identical cookies from a jar containing ten.
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The Bystander Effect
People are less likely to help someone in distress when others are present, because responsibility feels diffused. Darley and Latané (1968) found that participants who believed they were the only witness to a seizure helped 85% of the time, compared with 31% when they believed four others could also hear it.
Studying these effects online
Most of these phenomena were first demonstrated with pen-and-paper tasks or staged laboratory scenes, but many of them can be measured with a short browser experiment: an anchoring or endowment study needs only a few jsPsychHtmlButtonResponse or jsPsychSurveyText trials, and the manipulation can be assigned as a between-subject condition. Cognition hosts jsPsych experiments, balances participants across conditions on the server and stores every response as soon as it is given, so a replication of a classic effect can be online in an afternoon. See our guide to behavioral economics experiments for worked examples.
Conclusion
These ten effects are among the most replicated findings in behavioral science, and also among the most widely applied, from pricing and public policy to the design of consent forms. Knowing them helps you recognise when your own judgment is being nudged, and gives you a ready list of paradigms to adapt for your next study.