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Friday, November 26, 2021

Paranoia, self-deception and overconfidence

Rossi-Goldthorpe RA, et al (2021) 
PLoS Comput Biol 17(10): e1009453. 


Self-deception, paranoia, and overconfidence involve misbeliefs about the self, others, and world. They are often considered mistaken. Here we explore whether they might be adaptive, and further, whether they might be explicable in Bayesian terms. We administered a difficult perceptual judgment task with and without social influence (suggestions from a cooperating or competing partner). Crucially, the social influence was uninformative. We found that participants heeded the suggestions most under the most uncertain conditions and that they did so with high confidence, particularly if they were more paranoid. Model fitting to participant behavior revealed that their prior beliefs changed depending on whether the partner was a collaborator or competitor, however, those beliefs did not differ as a function of paranoia. Instead, paranoia, self-deception, and overconfidence were associated with participants’ perceived instability of their own performance. These data are consistent with the idea that self-deception, paranoia, and overconfidence flourish under uncertainty, and have their roots in low self-esteem, rather than excessive social concern. The model suggests that spurious beliefs can have value–self-deception is irrational yet can facilitate optimal behavior. This occurs even at the expense of monetary rewards, perhaps explaining why self-deception and paranoia contribute to costly decisions which can spark financial crashes and devastating wars.

Author summary

Paranoia is the belief that others intend to harm you. Some people think that paranoia evolved to serve a collational function and should thus be related to the mechanisms of group membership and reputation management. Others have argued that its roots are much more basic, being based instead in how the individual models and anticipates their world–even non-social things. To adjudicate we gave participants a difficult perceptual decision-making task, during which they received advice on what to decide from a partner, who was either a collaborator (in their group) or a competitor (outside of their group). Using computational modeling of participant choices which allowed us to estimate the role of social and non-social processes in the decision, we found that the manipulation worked: people placed a stronger prior weight on the advice from a collaborator compared to a competitor. However, paranoia did not interact with this effect. Instead, paranoia was associated with participants’ beliefs about their own performance. When those beliefs were poor, paranoid participants relied heavily on the advice, even when it contradicted the evidence. Thus, we find a mechanistic link between paranoia, self-deception, and over confidence.