Placebo Effect of Control Settings in Feeds Are Not Always Strong

Recent work has catalogued a variety of "dark" design patterns, including deception, that undermine user intent. We focus on deceptive "placebo" control settings for social media that do not work. While prior work reported that placebo controls increase feed satisfaction, we add to this body of knowledge by addressing possible placebo mechanisms, and potential side effects and confounds from the original study. Knowledge of these placebo mechanisms can help predict potential harms to users and prioritize the most problematic cases for regulators to pursue. In an online experiment, participants (N=762) browsed a Twitter feed with no control setting, a working control setting, or a placebo control setting. We found a placebo effect much smaller in magnitude than originally reported. This finding adds another objection to use of placebo controls in social media settings, while our methodology offers insights into finding confounds in placebo experiments in HCI.

• Human-centered computing → HCI theory, concepts and models; User studies; Empirical studies in HCI .