Associations between Case Fatality Rates and Self-Reported Fear of Neoplasms and Circulatory Diseases

Background. According to decision by sampling theory, people store relative frequencies of events in memory, and these values constitute subjective representations of events. Because fear is a natural response to the threat of death, we hypothesized that case fatality rate (CFR) statistics, which represent how deadly a disease is, would be positively correlated with self-reported fear ratings of neoplasms and circulatory diseases. Methods. Participants (N = 239) were asked to rate various neoplasms and circulatory diseases (110 diseases in total) on fear, typicality, and disgust scales (e.g., 1 = no fear, 10 = intense fear). They also estimated mortality and morbidity rates for the same set of diseases. Finally, they completed the Berlin Numeracy Test. CFRs were obtained from the World Health Organization (WHO) database. The association between relative CFR and fear ratings was tested using correlation analyses and a multilevel linear model with Bayesian inference techniques. Results. We found that fear ratings were related to relative CFRs (r = 0.42, [0.25, 0.56], BF = 3511). This effect was present on aggregate and, to some extent, on individual levels, even after controlling for other ratings, morbidity rate, participants' estimates of mortality and morbidity statistics, numeracy, sex, age, and knowledge of WHO statistics. Also, women rated neoplasms as more frightening than circulatory diseases, and typicality ratings were related to morbidity rates. Limitations. Limited number of diagnostic entities and categories, lack of control over the technicality of disease names and participants' experience of diseases, and study sample (83% young women). Conclusions. We present initial evidence that implicit acquisition of CFRs of diseases through everyday experience may be related to the intensity of fear reactions to them.