Forever a subjective science: the bias against psychological evidence motivated by political party identification

Abstract

To further investigate the bias against psychological methodology, this study assessed the difference between quality ratings of two types of psychological evidence (MRI scan or cognitive pencil-and-paper testing) given by an expert witness. Additionally, a language manipulation (subjective or objective) and participants’ political party affiliation were assessed in regards to quality ratings. Results indicated a bias against behaviorally-based psychological evidence compared to the neuroscience-based psychological evidence, with neuroscience evidence rated more favorably than behaviorally based evidence. This rating was accentuated in the evidence conditions when participants were motivated by their political preference. Participants who identified with the political party of the politician rated evidence more negatively than those who did not match his affiliation. The language manipulation failed to elicit strong enough effects in the results. Future research should focus on creating a stronger language manipulation and how moderating effects, such as political affiliation, can influence individuals’ opinions on evidence.