Results from a Conrmatory Replication Study of Bem (2011): Precognitive Detection of Erotic Stimuli?

In 2011, Dr. Bem published an article in the Journal of Personality and Social Psychology, the flagship journal of social psychology, in which he claimed that people can look into the future (Bem, 2011). In his first experiment, “precognitive detection of erotic stimuli”, participants were instructed as follows: “(...) on each trial of the experiment, pictures of two curtains will appear on the screen side by side. One of them has a picture behind it; the other has a blank wall behind it. Your task is to click on the curtain that you feel has the picture behind it. The curtain will then open, permitting you to see if you selected the correct curtain.” In the experiment, the location of the pictures was random and chance performance is therefore 50%. Nevertheless, Bem’s participants scored 53.1%, significantly higher than chance; however, the effect was present only for erotic pictures, and not for neutral pictures, positive pictures, negative pictures, and romantic-but-not-erotic pictures. Bem also claimed that the psi effects are more pronounced for extraverts, and that for certain erotic pictures women show psi but men do not. We set out to replicate Bem’s experiment in a purely confirmatory fashion. First we detailed our method, design, and planned analyses in a document that we posted online before a single participant was tested.1 As outlined in the online document, our replication focused on Bem’s key findings; therefore, we tested only women, used only neutral and erotic pictures, and included a standard extraversion questionnaire. We also tested each participant in two contiguous sessions. Each session featured the same pictures, but presented them in a different random order.2 The idea is that individual differences in psi –if these exist– lead to a positive correlation between performance on session 1 and session 2. Performance is quantified by the proportion of times that the participant chooses the curtain that hides the picture. Each session featured 60 trials, with 45 neutral pictures and 15 erotic pictures.