Paranoia in the Nonclinical Population

Abstract

A growing body of research demonstrates that paranoia is common in the general population. Four studies are presented that investigate factors associated with paranoia and naturalistic change in non-clinical groups. First, two experimental studies examine paranoia in the context of the Prisoner’s Dilemma Game (PDG), an interpersonal research paradigm, where two players have the choice to cooperate or compete with each other. The dominant and rational choice for both players is to compete, however each players’ individual reward would be greater if they both played cooperatively. Study 1 found that higher state paranoia was associated with the choice to compete. However the competitive choice can be selected due to distrust of the other player, or in order to maximise personal gain. The second experimental study employs a Three-Choice version of the PDG (PDG-Alt) that includes the option to withdraw, the rational choice when distrust of the other player is high. Higher state paranoia was associated with the withdrawal choice. These studies conclude that the withdrawal choice in the PDG –Alt provides a potential behavioral marker of state paranoia. Second, two studies examine naturalistic change in nonclinical paranoia. Idiosyncratic accounts of a single past paranoid experience are elicited and variations in dimensions known to be important in clinical paranoia are examined. Results show that levels of preoccupation, distress, impact on well being and conviction that harm was intentional significantly reduce over time. However the amount of time passed since the experience occurred is not significantly associated with level of change. Finally, in Study 4 a qualitative investigation is presented that identifies themes associated with change in nonclinical experiences of paranoia. The thesis concludes with a discussion of the theoretical, clinical and research implications of the findings.