Psychophysiological correlates of fear of movement-related pain assessed during a picture-based par-adigm in people with chronic shoulder pain

Fear of movement-related pain (FMRP) contributes to disability in chronic musculoskeletal pain. However, psychophysiological correlates of activity-specific threat appraisal during FMRP-eliciting tasks remain insufficiently understood. This cross-sectional study examined self-reports and psycho-physiological responses to shoulder-straining daily activities in individuals with chronic shoulder pain (CSP) and pain-free controls. Participants observed six pictures depicting shoulder movements select-ed as highly or minimally threatening. Each picture was presented five times in random order. Partic-ipants were informed that they would subsequently perform the activities. Following each presenta-tion, participants rated anticipated fear, urge to avoid, and expected harmfulness. Electrodermal ac-tivity, pupil diameter, heart rate, respiratory rate, and gaze behavior were recorded continuously. Self-reports differentiated between highly and minimally threatening activities and were higher in the CSP group (p≤0.001). SCL differentiated between threat categories, with more pronounced responses in the CSP group (pBH-corrected=0.008; f2=0.029). Within the CSP group, SCL correlated weakly with ratings of fear (ρ=0.137; pBH-corrected=0.008) and harmfulness (ρ=0.127; pBH-corrected=0.013), but not urge to avoid (ρ=0.022; pBH-corrected=0.763). Pupil dilation (pBH-corrected≤0.001; f2=0.039) and gaze be-havior (pBH-corrected=0.006; f2=0.067) differed between individual pictures in the CSP group but did not consistently differentiate the predefined threat categories. Heart rate and respiratory rate showed no consistent effects. This is the first shoulder-specific picture-viewing paradigm combining self-reports with several psychophysiological measures and the first study to examine pupil dilation as a potential correlate of FMRP. The findings suggest that electrodermal activity may reflect sympathetic arousal related to activity-specific threat appraisal during FMRP-eliciting picture-viewing.