The effect of horizontal eye movements on free recall: a preregistered adversarial collaboration.

A growing body of research has suggested that horizontal saccadic eye movements facilitate the retrieval of episodic memories in free recall and recognition memory tasks. Nevertheless, a minority of studies have failed to replicate this effect. This article attempts to resolve the inconsistent results by introducing a novel variant of proponent-skeptic collaboration. The proposed approach combines the features of adversarial collaboration and purely confirmatory preregistered research. Prior to data collection, the adversaries reached consensus on an optimal research design, formulated their expectations, and agreed to submit the findings to an academic journal regardless of the outcome. To increase transparency and secure the purely confirmatory nature of the investigation, the 2 parties set up a publicly available adversarial collaboration agreement that detailed the proposed design and all foreseeable aspects of the data analysis. As anticipated by the skeptics, a series of Bayesian hypothesis tests indicated that horizontal eye movements did not improve free recall performance. The skeptics suggested that the nonreplication may partly reflect the use of suboptimal and questionable research practices in earlier eye movement studies. The proponents countered this suggestion and used a p curve analysis to argue that the effect of horizontal eye movements on explicit memory did not merely reflect selective reporting.