The benefits of knowledge: Information about survival, sexual behaviour and forward-looking decisions

Recent improvements in adult life expectancies in high HIV-prevalence sub-Saharan African low-income countries have reversed previous adverse trends in adult survival during the 1990s and early 2000s when the HIV/AIDS epidemic considerably reduced life expectancies. Despite these improvements, many individuals have distorted survival perceptions and are overly pessimistic about their own survival. For example, mature adults (persons aged 45+) in the Malawi Longitudinal Study of Families and Health (MLSFH) report subjective probabilities of surviving for the next 5 years of about 46–58%, compared to 83–87% suggested by current life-tables. This pessimism is likely to influence important forward-looking behaviours. This paper provides evidence from a randomized controlled trial that provided mature adults with information about population-level mortality through an interactive information session in Malawi. We find that one year after the intervention, treated individuals update upward their beliefs about the survival of others –including individuals who are HIV positive– but not their own survival. This is consistent with a Bayesian framework in which individuals have more private information about their own survival than about the survival of others. Despite the lack of revision about own survival, we observe changes in behaviour which seems to be driven by the externalities of other people living longer. Treated individuals revise upward their beliefs about contracting HIV if one has multiple sex partners. This is in line with their perception that HIV positive people live longer, making the pool of available partners riskier. Likely driven by this increase in the transmission risk perception, treated individuals are less likely to engage in risky sexual practices one year after the intervention compared to the control group. These findings suggest that providing information about population-level mortality might be a useful policy tool to reduce risky sex in sub-Saharan Africa.

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