More than just fear: Development and psychometric evaluation of the Spider Distress Scale to assess spider fear and spider-related disgust.

Spider fear is an excellent model to experimentally study processes in the maintenance and treatment of long-lasting fears. A valid, reliable, and practical tool to assess spider-related distress dimensionally, and to differentiate between spider-related fear and disgust in a time-sensitive manner, may help to better understand individual differences in these two emotions and to tailor treatments accordingly. We developed a concise self-report questionnaire, the Spider Distress Scale (SDS), that combines the strengths of established spider fear questionnaires and addresses their shortcomings. We explored (study 1 and 2) and confirmed (study 3) a two-factor structure of the SDS in samples from the general population (n = 370; n = 360; n = 423), recruited online via Prolific Academic from the United Kingdom, the Netherlands, and the United States. The fear and disgust factors of the SDS are highly internally consistent and the SDS has excellent test-retest reliability. We found good convergent and discriminant validity, based on self-report measures and spider behavioural approach tasks, and the SDS successfully differentiated between individuals with and without spider fear (study 4, n = 75). Our series of studies suggests that fear and disgust are functionally related, but that disgust towards spiders can be differentially assessed when focussing on unique elements of disgust-related information.