Getting used to risks : reference dependence and risk inclusion

Experimental and field evidence show that people perceive and evaluate new risks differently from risks that are common. In particular, people get used to the presence of certain risks and become less eager to avoid them. We explain this observation by including risks in the reference states of individuals, which requires a more general concept of the reference state than has previously been considered in the literature. We find two effects. First, the inclusion of the risk in the reference state changes its evaluation. A risk being present on the market induces a selfenforcing process of increasing acceptance of this risk without any new information becoming available or people's tastes changing. We term this the risk inclusion effect. Second, a risk with lower inherent (reference-independent) utility may be preferred to a risk with higher inherent utility if individuals are more used to accepting the former than the latter. This leads to inefficient decisions if habituation is seen as contributing less to welfare than inherent utility. Both effects have implications for the optimal regulation of risks. -- habituation ; risk perception ; reference-dependent preferences ; WTA/WTP disparity ; health risk