A review of the worst performance rule: Evidence, theory, and alternative hypotheses

This paper reviews evidence, theory, and alternative hypotheses for the worst performance rule (WPR), which states that on multitrial cognitive tasks, worst performance trials predict general intelligence (g) better than best performance trials. A review of the relevant evidence indicates that the WPR has been found for a variety of participants, tasks, and measures. A review of relevant theories reveals that the WPR appears to be related to cognitive factors (e.g., lapses in working memory) as well as biological factors (e.g., individual differences in neural oscillations). A review of alternative hypotheses shows that the WPR cannot be attributed to statistical or data artifacts such as outliers, unreliable measurement, or variance compression. The preponderance of evidence supports the hypothesis that the WPR holds for cognitive tasks high in g saturation but not for cognitive tasks low in g saturation. The paper ends with a call for research on the causes of the WPR and for research on the correlates of best performance.