The Act of Measurement: The Influence of Behavioural Tests on Spider Fear and Disgust.

Behavioural assessments offer clinically relevant insights into anxious symptomatology, complementing self-report questionnaires in monitoring treatment effects. However, as a behavioural test is a form of brief exposure, it might not solely measure distress, but also influence it. In this study, we investigated whether measuring spider avoidance behaviour changes spider-related distress. Seventy-five individuals with a broad range of spider fear provided self-reported fear and disgust ratings, using the Spider Distress Scale, before and after engaging in a tarantula and in a house spider behavioural approach task (BAT). We found that self-reported fear, but not disgust, decreased after engaging in the behavioural assessments. A subsequent exploration within low- and high-fear subgroups showed that this pattern was driven by low-fear individuals, as in high-fear individuals spider fear and disgust remained unaffected by the behavioural assessments. Spider fear did not decrease on two exploratory questionnaires. In principle, these findings are promising for the validity of behavioural assessments in translational research where sub-clinical samples are typically targeted. However, they emphasise the need to carefully translate laboratory findings to (sub-)clinical populations, not only due to varying fear levels, but also because behavioural assessments may be experienced differently in the context of a treatment study.