Intrinsic Motivation Inventory: An Adapted Measure for Schizophrenia Research

This article describes the psychometric validation of a scale designed to measure intrinsic motivation (IM) in schizophrenia. Recent studies have highlighted the relationship between motivation and functional outcome in schizophrenia and identified IM as an important mediating factor between neurocognition and psychosocial outcome. It therefore becomes imperative to have validated measures of IM for empirical use. To that end, we validated a self-report IM scale that gauges the central motivational structures identified by Self-determinism Theory as pertinent to cognitive task engagement, skill acquisition, treatment compliance, and remediation outcome. Participants were schizophrenia outpatients involved in a cognitive remediation study (n = 58), a convenience subsample of clinically stable schizophrenia outpatients (n = 15), and a group of healthy normals (n = 22). The Intrinsic Motivation Inventory for Schizophrenia Research (IMI-SR) is a concise instrument, possessing good internal consistency (alpha = .92) and test-retest reliability (intraclass correlation = .77). Data were analyzed to abridge the original 54 items into a final 21-item questionnaire comprised of 3 domains relevant to motivation for treatments (interest/enjoyment, perceived choice, value/usefulness). The scale was highly associated with germane constructs of motivation for health-related behaviors, including perceived competency for attempting challenging tasks and autonomous treatment engagement. Importantly, the scale was able to distinguish improvers and nonimprovers on a cognitive task and actual learning exercises, delineate high vs low treatment attendance, and demonstrate sensitivity to motivational changes due to intervention variation. The IMI-SR is a viable instrument to measure IM in schizophrenia as part of a cognitive remediation protocol or psychosocial rehabilitation program.