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Description: The Need for Cognition Scale (NCS) is a self-report scale measuring individual differences in the tendency to engage in and enjoy thinking. The shortened version with 18 items (NCS-18; Cacioppo et al., 1984) has widely been administered in research on persuasion, critical thinking, and educational achievement. Whereas most studies advocated for essential uni-dimensionality, the question remains which psychometric model yields the best representation of the NCS-18. In the present study, we compared six competing measurement models for the NCS-18 with meta-analytic structural equation models using summary data of 87 samples (N = 90,215). Results demonstrated that the negatively worded items introduced considerable measurement bias that was best accounted for with an acquiescence model. In a further analytical step, we showcased how the pooled correlation matrix can be used to compile short versions of the NCS-18 via Ant Colony Optimization. We examined model fit and reliability of short scales with varying item numbers (between 4 and 15) and a balanced ratio of positively and negatively worded items. We discuss the potentials and limits of the newly proposed method.