UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Misconceptions about the safety benefit of booster seats : the ejection stereotype hypothesis Ishikawa, Takuro


This dissertation explores whether Lakatos’ methodology of scientific research programs and Elster’s notion of causal explanations can be used to drive innovation in injury prevention research. For illustration purposes, the problem of low rates of booster seat use is applied to a case study. Contrary to popular belief, the purpose seat belts is not solely to prevent people from being ejected out of the car, but to redirect crash forces to stronger parts of the body: hips and chest. Children between the ages of 4 and 8 years are usually too small to wear the seat belt across the hips and chest, and may end up with the straps on their bellies and neck. If a child wears it in this way, the seat belt directs crash forces to the child’s internal organs or spine, potentially causing fatal injuries. For this reason, children of these ages require a booster seat; a device that raises the child and ensures the seat belt is placed correctly across the hips and chest. Unfortunately, in Canada, 50% of children aged 4 to 8 years ride in cars strapped in seat belts, but without booster seats. To address this problem, I formulate a hypothesis that explains why booster seat use is infrequent: parents are prone to see injuries to vehicle occupants as resulting from ejection. This fixation on ejection makes them more concerned about the child being thrown through the windshield, and less worried about the dangers of early use of seat belts. I term this proposition the ejection stereotype hypothesis. This dissertation spans over philosophy of science, psychology, decision science, visual arts, and injury prevention. After summarizing different views of scientific progress and discussing the philosophy of booster seat research, fuzzy-trace theory and the ejection stereotype are described. Next, a psychological study that reports a falsification test of the ejection stereotype is reported. Following, a visual arts project is described in terms of how Tufte’s principles of information design were used to develop an infographic to correct the ejection stereotype. Finally, a proof-of-concept pilot study to test the efficacy of the infographic is reported.

Item Media

Item Citations and Data


Attribution-NonCommercial-NoDerivatives 4.0 International