MEDIC: Development and validation of a new instrument to assess emotional reactivity to medical stimuli in a representative community sample of adults.

To support investigation of the etiology and psychophysiology of medical traumatic stress, we developed a standardized set of emotionally-salient medical images, called the 'MEDical Image Collection' (MEDIC), for use in neuroimaging or psychological research. This study aimed to establish internal consistency, test re-test reliability, and congruent validity of the image set. A representative sample of 300 adults in the United States were recruited via research recruitment platform, Prolific. Participants rated 124 images depicting medical stimuli on one of two dimensions: emotional arousal (i.e., how strongly an evoked emotion is felt) or affective valence (i.e., how positive or negative the evoked emotion is). Sociodemographic and health-related characteristics, including experiences during the COVID-19 pandemic, were also assessed. To assess test re-test reliability, a subset (n = 200) rated the images on the same dimension a second time, 3 months later. The MEDIC image set was found to: (a) elicit a range of emotional arousal and valence ratings, (b) have excellent inter-rater reliability, (c) moderate test-retest reliability, and (d) good face validity. Results indicate the new MEDIC 124-image set is a reliable and valid instrument, enabling researchers to provide context-specific and emotionally-salient stimuli to individuals when studying affective responses in relation to health and medicine.