Related Experiment Video
Updated: Oct 3, 2026

Use of a Psychophysiological Script-driven Imagery Experiment to Study Trauma-related Dissociation in Borderline Personality Disorder
Published on: March 8, 2018
Signs and Symptoms of Psychotic Illness (SSPI): a rating scale
Peter F Liddle1, Elton T C Ngan, Gary Duffield
1Department of Psychiatry, University of British Columbia, Canada. peter.liddle@nottingham.ac.uk
Background:
In the rating scales commonly used for assessing response to antipsychotic treatment, individual items embrace symptoms that apparently arise from distinguishable pathophysiological processes and might be expected to respond differently to treatment.
Aims:
To test the reliability, sensitivity to change and factor structure of a new scale for the assessment of the Signs and Symptoms of Psychotic Illness (the SSPI).
Method:
Interrater reliability was evaluated by determining the intraclass correlation for the ratings of 63 patients. Sensitivity to change was assessed in a longitudinal study of 33 patients. Factor structure was determined from scores for 155 patients.
Results:
The intraclass correlation was satisfactory for all individual items and excellent for the total score. Scores were sensitive to change. A change in Clinical Global Impression of one unit corresponded to an SSPI total score change of 31%. Factor analysis revealed five clusters of symptoms.
Conclusions:
The SSPI provides a sensitive and reliable measure of the five major clusters of symptoms that occur commonly in psychotic illness.
Related Concept Videos
Self-Report Tests of Personality
Positive Symptoms Schizophrenia: Hallucinations and Delusions
Hallucinations
Hallucinations in...
Psychosis and Antipsychotic Drugs: Overview
Positive Symptoms of Schizophrenia: Hallucinations and Delusions
Thought Disorders
Disorganized and unusual thought processes mark thought disorders in schizophrenia. One key feature is disorganized speech, where an individual's conversation includes loosely...
Schizophrenia
Negative and Cognitive Symptoms of Schizophrenia
Negative Symptoms
Negative symptoms of schizophrenia manifest as deficits in normal emotional and behavioral functioning, profoundly impacting daily life. Individuals with schizophrenia often display a flat affect, characterized by a near-total absence of emotional expression,...
