Negativity bias, positivity bias, and valence asymmetries: Explaining the differential processing of positive and negative information

Distinguishing between good and bad is a fundamental task for all organisms. However, people seem to process positive and negative information differentially, described in the literature as instances of negativity bias, positivity bias, or valence asymmetries. We provide an overview of these processing differences and their explanations. First, we review negativity advantages: People attend more to negative information, recall it more, and weigh it more heavily, relative to positive information. Second, we review positivity advantages: People process positive information faster, have broader associations from it, and show stronger congruency effects, relative to negative information. We then discuss existing explanations for these differential effects in terms of phylogenetic pressures, correlates of valence, diagnosticity, mobilization-minimization, and top-down vs. bottom-up processing. Finally, we suggest the differential similarity of positive and negative information as a unifying explanation. We delineate why positive information should be more alike relative to negative information, and how differential similarity translates to the observed processing differences. Then we show how the similarity explanation leads to novel predictions and how it solves old puzzles. Similarity thereby provides an explanatory construct for both positivity and negativity advantages, allowing precise quantitative predictions for valence asymmetries beyond the mere classification of good and bad.