 First, the extent to which we ignore the risks of daily life is not a fully rational process. In many cases, our attitude regarding risks is a function of features of the situation that are not correlated directly with the risk level, such as our perceived level of control and our familiarity with the activity (Tversky, Kahneman 1974; Tversky, Kahneman 1981; Slovic 1987; Weinstein 1989). Second, to the extent that the process of ignoring some risks is rational, we are involved in a process of determining which risks are worth paying attention to. Some risks are so low that they are not worth paying attention to. Consideration of them would be more harmful (would cost us more) than the expected value of being aware of them in the first place.