The procedure of the two studies was similar. The participants were first asked
to evaluate one problem; they were then shown the other problem and were asked
to respond to it, with an explicit instruction to consider both problems before
responding. The independent variable was the order of presentation of the two
problems. The participants in Study 1 were 100 visitors at the San Francisco
Exploratorium. They were asked to rate the importance of each problem and the
satisfaction they would expect to get from making a contribution to its solution
both on a 0]6 scale.. The data for Study 2 are drawn from a larger study, in which
participants were jury-eligible residents of Austin. Some participants Ns130.
provided ratings of satisfaction as in Study 1. Others Ns261. indicated their
WTP to contribute to a solution; when they encountered the second problem they
were instructed to treat it as the only cause to which they would be asked to
contribute.