A New Performance-Based Measure of Personality Functioning Impairment: Development and Evaluation of Reliability and Validity

At the center of many dimensional models of personality is personality functioning impairment. Professional practice guidelines for personality assessment strongly advise the use of multiple methods of measurement, but available measures of personality functioning impairment are limited to self-report, clinician-/informant-rated, and interview methods. Although researchers have begun investigating established performance-based instruments’ potential for assessing personality functioning impairment, administration and scoring of these instruments is complex and the latent variables they measure ostensibly diverge from personality functioning impairment as described in the ICD-11 and DSM’s Alternative Model for Personality Disorders (AMPD). To address the absence of an easily administered, scored, and interpreted performance-based measure of personality functioning impairment, we developed a novel instrument that meets these criteria and directly parallels the AMPD: The Level of Personality Functioning Scale – Questionnaire-based Implicit Association Test (LPFS-qIAT). Several aspects of the LPFS-qIAT’s reliability and validity were evaluated across four studies. This initial psychometric evaluation produced encouraging evidence supporting the new instrument’s internal and retest reliability as well as its convergent, discriminant, and criterion-related validity. As the first performance-based measure of personality functioning impairment that aligns with the ICD-11 and AMPD that is easily administered, scored, and interpreted, the LPFS-qIAT stands to become a valuable tool in both research and clinical practice.