Operationalizing the Construct of the Internal Saboteur: Development and Psychometric Validation of the Internal Saboteur Scale (ISS).

The internal saboteur may be understood as a multidimensional configuration of maladaptive inner processes involving recurrent negative self-evaluation, distressing relational expectations, repetitive negative thinking, and self-undermining inner experiences. Within this framework, the present study aimed to develop and examine the psychometric properties of the Internal Saboteur Scale (ISS), a self-report measure designed to assess this construct. A sample of 328 Italian adults (women 71.6%; Mage = 37.37, SD = 14.88) completed the survey. Confirmatory factor analyses supported both an eight-factor correlational model and a theoretically meaningful higher-order model, in which the lower-order dimensions were grouped into four broader domains: Negative Relational Expectations (Expected Rejection; Expected Judgment), Self-Devaluation (Negative Self-Appraisal; Interpersonal Unworthiness), Rumination (Retrospective Rumination; Anticipatory Rumination), and Internal Destructiveness (Helplessness; Defensive Relational Withdrawal). Measurement invariance across gender was also supported. All dimensions showed satisfactory-to-good internal consistency. Furthermore, ISS scores were negatively associated with secure attachment, self-reassurance, and mentalizing and positively associated with insecure attachment, self-criticism, shame, and anger. Overall, the ISS appears to be a theoretically grounded and psychometrically promising instrument for the assessment of maladaptive inner dialogue and self-sabotaging internal processes. It may represent a useful tool for both research and clinical practice, particularly in supporting transdiagnostic assessment and case formulation.