13. The Landis Facial Expressions Experiment
In 1924, psychologist Carney Landis conducted an experiment to determine if specific facial expressions are universally associated with certain emotions. Participants were exposed to various stimuli, including smelling ammonia, viewing explicit images, and placing their hands in buckets of live frogs. The most controversial aspect involved instructing participants to decapitate a live rat; approximately two-thirds complied, while the rest witnessed Landis performing the act himself. The study concluded that facial expressions vary significantly among individuals, highlighting the ethical concerns of inducing distress for research purposes. (psychologytoday.com)