Developing and Evaluating a Situated Assessment Instrument for Trichotillomania: The SAM² TAI

Trichotillomania (hair pulling disorder) is characterized by the recurrent and repetitive pulling of one’s own hair, often resulting in distress for the individual. Being able to accurately measure trichotillomania is essential for understanding hair pulling and developing interventions to decrease pulling. Most current assessment measures are unsituated, asking an individual to assess their pulling by abstracting across unspecified life situations to construct overarching impressions. This abstraction process can potentially lead to inaccurate judgements that ignore important sources of situational variance. We used the Situated Assessment Method (SAM²) to develop a situated psychometric instrument for assessing trichotillomania: the SAM2 Trichotillomania Assessment Instrument (SAM2 TAI). Using the SAM2 TAI, participants in two studies (n = 117 and n = 99) evaluated 52 situations for pulling frequency and urge strength, along with a set of processes known to influence pulling (e.g., external triggers, reduction of negative emotion, situational control, emotion regulation). As expected, large reliable individual differences emerged across these measures of trichotillomania, together with substantial situational effects and situation by individual interactions. High levels of construct and content validity were also observed, demonstrating that the SAM2 TAI provides meaningful assessments of constructs associated with trichotillomania. Prediction of trichotillomania at both the group and individual levels supported theoretical models of trichotillomania in the literature, while establishing individual prediction profiles that varied widely. Interestingly, the SAM2 TAI was only moderately related to a well-established unsituated measure of trichotillomania, the MGH-HPS, indicating that situated and unsituated measures capture different information.