Shining a Light on Dark Patterns

67 Pages Posted: 7 Aug 2019 Last revised: 29 Mar 2021

See all articles by Jamie Luguri

Jamie Luguri

University of Chicago

Lior Strahilevitz

University of Chicago Law School

Date Written: March 29, 2021


Dark patterns are user interfaces whose designers knowingly confuse users, make it difficult for users to express their actual preferences, or manipulate users into taking certain actions. They typically exploit cognitive biases and prompt online consumers to purchase goods and services that they do not want, or to reveal personal information they would prefer not to disclose. Research by computer scientists suggests that dark patterns have proliferated in recent years, but there is no scholarship that examines dark patterns’ effectiveness in bending consumers to their designers’ will. This article provides the first public evidence of the power of dark patterns. It discusses the results of the authors’ large-scale experiment in which a representative sample of American consumers were randomly assigned to a control group, a group that was exposed to mild dark patterns, or a group that was exposed to aggressive dark patterns. All groups were told they had been automatically enrolled in an identity theft protection plan, and the experimental manipulation varied what acts were necessary for consumers to decline the plan. Users in the mild dark pattern condition were more than twice as likely to remain enrolled as those assigned to the control group, and users in the aggressive dark pattern condition were almost four times as likely to remain enrolled in the program. There were two other striking findings. First, whereas aggressive dark patterns generated a powerful backlash among consumers, mild dark patterns did not – suggesting that firms employing them generate substantial profits. Second, less educated subjects were significantly more susceptible to mild dark patterns than their well-educated counterparts. Both findings suggest that there is a particularly powerful case for legal interventions to curtail the use of mild dark patterns.

The article concludes by examining legal frameworks for ameliorating the dark patterns problem. Many dark patterns appear to violate federal and state laws restricting the use of unfair and deceptive practices in trade. Moreover, in those instances where consumers enter into contracts after being exposed to dark patterns, their consent could be deemed voidable under contract law principles. The article proposes a quantitative bright-line rule for identifying impermissible dark patterns. Dark patterns are presumably proliferating because firms’ secret and proprietary A-B testing has revealed them to be profit maximizing. We show how similar A-B testing can be used to identify those dark patterns that are so manipulative that they ought to be deemed unlawful.

Keywords: Dark Patterns, Sludge, Nudge, Experiment, Empirical, Psychology, Federal Trade Commission, FTC, Internet, Cyberlaw, Behavioral Economics, Regulation, Marketing, Contracts, Consumer Protection, Section 5, Privacy by Design, Default Rules, Unfair Competition, Deceptive Practices in Trade, UX Design

Suggested Citation

Luguri, Jamie and Strahilevitz, Lior, Shining a Light on Dark Patterns (March 29, 2021). 13 Journal of Legal Analysis 43 (2021) , University of Chicago Coase-Sandor Institute for Law & Economics Research Paper No. 879, U of Chicago, Public Law Working Paper No. 719, Available at SSRN: or

Jamie Luguri

University of Chicago ( email )

1101 East 58th Street
Chicago, IL 60637
United States

Lior Strahilevitz (Contact Author)

University of Chicago Law School ( email )

1111 E. 60th St.
Chicago, IL 60637
United States
773-834-8665 (Phone)
773-702-0730 (Fax)

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