Psychotic-like or unusual subjective experiences? The role of certainty in the appraisal of the subclinical psychotic phenotype.

The multi-dimensional features of Unusual Subjective Experiences (USEs) may be more accurate indicators of psychosis-proneness than simple frequency count. We tested whether subjective certainty or uncertainty of the occurrence of USEs can influence perceived wellbeing. Five hundred and four undergraduate students completed measures of delusion- and hallucination-proneness, general health and emotional processing. Participants' responses on the delusion- and hallucination-proneness scales were dichotomized on the basis of their certainty level. Results showed that, USEs rated with certainty were associated with poor self-perceived health and difficult emotional processing, while those rated with uncertainty were not. Certainty of USEs was associated with increased distress and may be important in characterizing psychopathological significance. Specific characteristics associated with USEs may be more important than their frequency in predicting psychosis risk.