Does assessment alter responses? An examination of measurement reactivity in an ecological momentary assessment of body comparisons

Introduction: Body comparisons have been implicated in body dissatisfaction and eating disorder development. Ecological momentary assessment (EMA) has been used to capture body comparisons in everyday life; however, the potential for measurement reactivity this approach has on EMA responses has yet to be examined. The present study systematically evaluated measurement reactivity in EMA of body comparisons. Methods: Undergraduate women (N = 75) completed four surveys daily for 11 days; Days 1–4 did not include comparison assessments and Days 5–11 did. Changes were examined in related EMA measures between these time periods and individual difference measures pre- and post-EMA. Results: A within-person MANOVA showed no significant change in the individual difference measures. Multilevel analyses revealed that participants reported fewer comparisons as day of study increased. When they completed EMA with versus without comparison items, they reported fewer occasions of loss of control while eating and less pleasant social company at time of assessment. Discussion: Findings suggest limited concern for reactivity in this approach, though researchers examining body comparisons, loss of control eating, and perceptions of social company should be cautious when interpreting their findings and consider examining reactivity directly. Future research on body comparisons should also consider using run-in periods to improve data quality.