The Salience of Information: Evidence from a Health Information Campaign in Rural China

Besides increasing knowledge, there is another potential mechanism at work when information is delivered to a treatment group: increasing the salience of existing knowledge. We use data from a randomized controlled trial of a health information campaign to explore the relative importance of this additional mechanism in a real-world environment. The health information campaign addressed the benefits of wearing eyeglasses and provided information meant to address the common misconceptions that contribute to low adoption rates of eyeglasses. In total, our study sample included 931 students with poor vision (mostly myopia), their parents, and their homeroom teachers in 84 primary schools in rural China. We find that the health information campaign was able to successfully increase student ownership and wearing of eyeglasses, relative to a control group. We demonstrate that the campaign had a larger impact when levels of preexisting information among certain subgroups of participants-namely, parents of students-were higher while we simultaneously provided new information to others. This suggests that the interaction between directed attention (i.e., salience) and baseline knowledge is important. We do not, however, find similar increases among teachers or the students themselves and additionally find no impacts on academic outcomes.