The Transaction Test

This article introduces the transaction test, a novel experimental method to detect whether deceptive designs (known as dark patterns) induce choices that are inconsistent with individual preferences. In a highly powered online experiment, we assess three dark patterns and one transparency-based remedy in decisions involving data protection. Compared to a placebo condition, dark patterns increase choice inconsistency by an effect in the range of 11-31% of the outcome in the control, depending on experimental conditions. The transparency-based remedy fails to mitigate these effects. We assess the robustness of the methodology and replicate the main findings in a controlled lab experiment. Our findings demonstrate how the transaction test, by providing an empirical assessment of the legal concept of unfairness, offers a flexible tool for the regulation of dark patterns and other commercial practices.