Since the first publication of the self-prioritization effect (SPE; Sui et al., 2012), researchers have been trying to understand the cognitive processes underlying this effect. Here, we assume that the effect can (at least partially) be explained by the Polarity Correspondence Principle (Proctor & Cho, 2006). This principle states that in binary classification tasks participants arrange the stimulus alternatives and response alternatives on plus and minus poles, respectively. Responses are faster if stimulus and response poles correspond. Applied to the SPE, in matching self-related trials all plus polarities meet (i.e., self-label, self-shape, yes response). To test this assumption, participants learned to associate geometric shapes with a self-relevant and one other-relevant label (Experiment 1) or two different other-relevant labels (i.e., the more common version of the paradigm; Experiment 2). In a between-design, participants were instructed to affirm either “mono-combinations” (label-shape combinations where label and shape refer to the same person) or “duo-combinations” (label-shape combinations where the label refers to one and the shape refers to another person). Thus, according to the polarity rationale, matching self-related trials are still “+++” in the “mono” condition, but “++–” in the "duo” condition. Accordingly, in the “mono”-block we found a clear SPE in both experiments. In the “duo” block, however, the SPE disappeared (Experiment 1) or was significantly reduced (Experiment 2). These results suggest that a substantial part of the SPE can be explained by the Polarity Correspondence Principle.