Purpose of the Scale

The purpose of the scale is to investigate in-session psychotherapeutic processes related to the mechanisms underlying the formation of delusional ideas.

Scale Analysis

The scale was developed by Zgantzouri and Nestoros in 1999. It includes 25 items that examine the formation of delusional ideas associated with schizophrenia and schizoaffective disorder. A seven-point Likert-type scale is used for scoring, with responses ranging from “strongly agree” to “strongly disagree.” The questionnaire is completed by individuals during therapy sessions with their psychotherapist. The scale is filled out specifically for each patient, allowing for the exploration of the broader conditions under which it is completed and leading to more specific conclusions.

Scoring and Statistical Analysis

For each mechanism of delusion formation, an overall score is calculated as the average of all items related to that mechanism. This allows for an evaluation of the extent to which an external rater agrees or disagrees with the specific part of the session and the mechanism involved in the emergence of these ideas as reflected in the scale.

Scale Validity

The scale demonstrates internal consistency and coherence among its statements. It also shows face validity and content validity. However, due to the lack of existing tools to measure the phenomenon, criterion validity has not been assessed.

Scale Reliability

The average of the measurements derived from multiple sessions and a sufficient number of relevant in-session events can provide a representative stability index regarding delusional ideas. In contrast, results from a single session would likely be very specific, as each session focuses on a particular issue.

References

Greek Literature
Zgantzouri, K. (2000). Psychotherapeutic processes in psychoses: the formation of delusional ideas in paranoid-type schizophrenia and schizoaffective disorder (Doctoral dissertation, University of Crete. School of Social Sciences. Department of Psychology).
International Literature
Zgantzouri, K. A., & Nestoros, J. N. (2000). Psychotherapy process research in schizophrenia paranoid type: The investigation of delusion formation through the evaluation of in-session events. In 13th International Symposium for the Psychological Treatments of Schizophrenia and Other Psychoses, Stavanger, Norway.