The clarity and correctness of visualized thrust actions: a description and insights from users and experts

This article presents three studies that evaluate the effectiveness of instructional pictures that visualize Heimlich maneuver thrusts. Firstly, a corpus study is used to describe a collection of 30 pictures employing a model in which the angle, perspective, body and hand positions of the first-aid helper and the victim, the thrust action and its depicted results are analysed. Results show a large variation in the visualizations of the same action. Secondly, 56 potential users of the pictures filled out a questionnaire to evaluate the clarity and correctness with which the action is displayed in five representative pictures from the corpus with Heimlich’s description of the thrust action as a reference. Results showed that the pictures were considered far from perfect. In particular, the clarity of the visualization of the helper applying pressure on the abdomen of the victim was considered the least clear and incorrect. Thirdly, six certified first-aid instructors gave their expert opinions on the five pictures. Their comments concentrate on the location of the hands which are depicted dangerously high on the front of the victim. These studies advance the annotation and evaluation methodologies for the investigation of visualized actions. Results serve authoring and analysis of multimodal instructions.