Illusory truth effect of health-related products: Importance of knowledge and interest
Abstract
The illusory truth effect is a phenomenon in which repeated exposure to stimuli increases their perceived truth. This study examined whether knowledge and interest in health-related problems play an important role in this effect. Participants were exposed for three times to ten advertisement images of health-related products (e.g., nutritional supplements) with messages describing their effects. Participants rated the perceived truth of the exposed and novel images. Thereafter, questions, including those on participants’ degree of knowledge of and interest in health-related problems, were presented. The results demonstrated that the exposed images were rated truer than novel ones, which confirms the illusory truth effect. Additionally, participants more interested in health exhibited higher levels of the illusory effect than those less interested only when they lacked sufficient knowledge about health, which revealed the mechanism underlying individual differences in this effect.