The many foibles of Likert scales challenge claims that self-report measures of self-control are better than performance-based measures.

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Self-control and executive functioning are often treated as highly related psychological constructs. However, measures of each rarely correlate with one another. This reflects some combination of true separability between the constructs and measurement differences. Traditionally, executive functioning is objectively measured as performance on computer-controlled tasks in the laboratory, whereas self-control is subjectively measured with self-report scales of predispositions and behaviors in everyday life. Self-report measures tend to better predict outcomes that should be affected by individual differences in control. Our two studies show that the original version of Tangney, Baumeister, and Boone's brief self-control scale (consisting of four positive and nine negative items) strongly correlates with self-esteem, mental health, fluid intelligence, but only weakly with satisfaction with life and happiness. Four variants of the original scale were created by reverse-wording the 13 original items and recombining them to form, for example, versions with all positive or all negative items. As the proportion of items with positive valence increased: (1) the outcomes with strong correlations in the original scale weakened and the weak correlations strengthened and (2) the mean overall scores increased. Both studies replicated a common finding that the original scale yields two factors in an exploratory factor analysis. However, the second factor is generated by method differences, namely, having items with both positive and negative valence. The second factor is induced by the common practice of reverse-coding the items with negative valence and the faulty assumption that Likert scales are equal-interval scales with a neutral-point at midscale.