An investigation into reasoning biases, mood and cognitive state, and subclinical delusional ideation.

Following research on reasoning and the continuum of delusional ideation, the present study attempted to investigate the impact of different experimentally-induced states (stress, paranoia, and neutral) on the jumping-to-conclusions reasoning bias in individuals with varying levels of subclinical delusional ideation (SDI). Participants (N=117) completed a measure of subclinical delusional ideation (the Peters et al. Delusions Inventory or PDI; Peters et al., 1999); and were randomly assigned to receive one of two experimental inductions (stress or paranoia), or no experimental induction; their performance on two probabilistic reasoning tasks – one easy and one challenging – was assessed. Although no differences were found between individuals with high vs. low subclinical delusional ideation in the no induction condition or following the paranoia induction, in the stress-induction condition, individuals with high levels of subclinical delusional ideation were significantly less likely to jump to conclusions on the easy reasoning task. No significant effects emerged on the more challenging task. Assessment of post-test paranoid thinking indicated our paranoia induction did not have its intended effect. Importantly, because there was no pre-test of anxiety, paranoid thinking, or reasoning to determine if they shifted after the inductions, results need to be interpreted with caution.