SSE PA 240721 Wittman




A German Version of The Retroactive Priming Task Shows Mixed Effects

Marc Wittmann, Felix Scheck, Julika Feldmann, Amelie Glaesmann, Julia Mossbridge & Daryl Bem

Introduction: We studied the retroactive priming effect with the software system from the study by Bem (2011, Exp. 4) where choice reaction times to a positive or negatively valenced photo were shown to be influenced by a following positive or negative word. In that prior work, emotionally congruent photo-word pairs led to shorter reaction times than emotionally incongruent pairs. Since the potentially influencing word appears after the button is pressed, this effect is described as retroactive psi effect. Here we report on two replication studies with German words. Two new analysis methods were applied: (1) since a response time could be driven by a regular anterograde priming effect of the word from the previous trial onto the photo of the subsequent trial, we assessed the influence of this standard anterograde priming effect; (2) in study 2 we controlled for potential false positive effects by utilizing a specially designed sham control task.

Methods: We tested n = 100 subjects on the computerized retroactive task in study 1; in study 2 we tested 95 subjects each (50 female) on the experimental and the sham control task. The dependent variable is the retroactive priming (RP) effect that was calculated by subtracting the mean RT (mean log RT) of incongruent trials from the mean RT (mean log RT) for congruent trials. A positive RP (log RP) indicates a faster response time for congruent trials than incongruent trials . For the sham control task in study 2, the same software environment was used with the sole difference of having a row of seven O’s appearing after the photo. Since no real picture-word pairs are established, any positive picture-word effect would have to be labeled as false positive (Walleczek & von Stillfried, 2019).

Results: According to confirmatory analyses the anomalous cognition hypothesis concerning a positive psi effect is rejected in both studies. There is a mean retroactive priming (RP) effect of 6 ms in study 1. Exploratory post-hoc analyses show a positive retroactive priming effect (33 ms) for men only (women: -17 ms). Men and women are significantly different from each other regarding RP and log RP. Men differ significantly from 0 for RP (p = .014) and log RP (p = .017). In study 2, a mean negative RP effect of 16 ms is detected, no gender difference is found. This overall negative priming value, faster reaction times for incongruent than for congruent pairs is marginally significant from 0 for RP (p = .081) and significant for log RP (p = .022). There is no significant effect in the sham control task and no substantial anterograde priming effect.

Discussion: From the perspective of a strictly confirmatory analysis, for these studies, the psi hypothesis of a retroactive priming effect in the German language version is rejected. The significant exploratory post-hoc analyses are nevertheless informative. We report typical patterns of outcomes in experimental parapsychology (Walach et al. 2009), namely there are clear deviations from null effects, which often cannot be attributed to chance variations (the negative log RP value across men and women in study 2), and deviations are not reproducible (the effect in men in study 1). We discuss the possibility that the IAPS photos, which were validated in the USA in the 1990ies and howculture-specific scenes might be outdated and not representative as emotional stimuli for young participants from central Europe. This can be seen in many category mistakes and slow reaction times in our student population. Future studies should attempt to use a different set of photos adjusted to the study population.

The Parapsychological Association is an international professional organization of scientists and scholars engaged in the study of psi (or ‘psychic’) experiences, such as telepathy, clairvoyance, psychokinesis, psychic healing, and precognition. The primary objective of the PA is to achieve a scientific understanding of these experiences.

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Published on May 12, 2022