The use of captions has grown in recent years in both traditional and new media, particularly in terms of the diversity of style, content, and function. Impact captions have emerged as a popular form of captions for hearing viewers and contain rich multimodal information which is employed to capture viewer attention and enhance engagement, particularly in situations where there is competition for viewer attention. Drawing upon relevance theory, we argue how impact captions could effectively attract and hold visual attention owing to their balance between processing effort and contextual effects. This exploratory study employs a dual-task paradigm and uses authentic materials and viewing situations to further examine the ability of multimodal impact captions to attract and retain overt visual attention amongst a small sample of TV viewers. Our results provide novel insight into the apparent highly individualised efficacy of impact captions, where we identify several variables of interest in participants’ viewing behaviours. We conclude with a discussion of the study’s contributions, limitations, and an outline for future work.