Open AccessMeasurement of Delusional Ideation in the Normal Population: Introducing the PDI (Peters et al. Delusions Inventory)
Author(s) -
Emmanuelle Peters,
Stephen Joseph,
Philippa Garety
Publication year - 1999
Publication title -
schizophrenia bulletin
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.823
H-Index - 190
eISSN - 1745-1701
pISSN - 0586-7614
DOI - 10.1093/oxfordjournals.schbul.a033401
Subject(s) - psychology , schizotypy , conviction , distress , delusion , normal population , clinical psychology , population , psychosis , ideation , schizophrenia (object oriented programming) , psychiatry , convergent validity , psychometrics , thought disorder , developmental psychology , internal consistency , medicine , environmental health , political science , law , cognitive science
The Peters et al. Delusions Inventory (PDI) was designed to measure delusional ideation in the normal population, using the Present State Examination as a template. The multidimensionality of delusions was incorporated by assessing measures of distress, preoccupation, and conviction. Individual items were endorsed by one in four adults on average. No sex differences were found, and an inverse relationship with age was obtained. Good internal consistency was found, and its concurrent validity was confirmed by the percentages of common variance with three scales measuring schizotypy, magical ideation, and delusions. PDI scores up to 1 year later remained consistent, establishing its test-retest reliability. Psychotic inpatients had significantly higher scores, establishing its criterion validity. The ranges of scores between the normal and deluded groups overlapped considerably, consistent with the continuity view of psychosis. The two samples were differentiated by their ratings on the distress, preoccupation, and conviction scales, confirming the necessity for a multidimensional analysis of delusional thinking. Possible avenues of research using this scale and its clinical utility are highlighted.