Two issues were investigated concerning the retrieval of recently acquired relevant information for solving riddle problems. First, although earlier research indicated that problem solvers often fail to retrieve relevant information unless they are explicitly informed of its relevance, Bowden (1985)suggested that uninformed subjects would benefit greatly from additional problemsolving time. In two experiments, we found that uninformed subjects solved more problems than did subjects who did not receive the information, but a simple model attributed this difference to these uninformed subjects "catching on" to the information's relevance after solving some problems. Second, the retrieval characteristics were examined by varying the proportion of problems for which clues were given. Informed subjects given clues for only half of the problems benefited (though perhaps not fully) from being informed, without incurring any cost from being misdirected on the unclued problems. The discussion focuses on some ways in which accessing relevant information may affect problem solving.How people access and use relevant knowledge is a central issue in cognition. As the emphasis in problemsolving research has shifted to the knowledge required to solve problems, increasing attention has been focused on questions about the access and use of such knowledge (e. g., Adams et al., 1988;Gentner & Landers, 1985; Gick & Holyoak, 1980Holyoak & Koh, 1987;Lockhart, Lamon, & Gick, 1988;Perfetto, Bransford, & Franks, 1983;Ross, 1984Ross, , 1987 Ross, , 1989a Ross, , 1989b Stein, Way, Benningfield, & Hedgecough, 1986; Weisberg, DeCamillo, & Phillips, 1978). A number of these studies have shown that subjects often fail to transfer relevant knowledge spontaneously to a new situation. Although this lack of transfer could be due either to failure to access the relevant information or to failure to use it once accessed, in many cases people fail to access the relevant information (though see Ross, 1987, 1989a, and Stein et al., 1986, for difficulties with the use of accessed information). These failures of access occur when the earlier information is analogous to the current problem (e.g., Gick & Holyoak, 1980 Reed, Ernst, & Banerji, 1974;Spencer & Weisberg, 1986) as well as when the earlier information is not analogous, but is very relevant to the current problem (e.g., Perfetto et al., 1983).It may be useful to make this idea more concrete with an example that is closely related to the current investigation. Perfetto et al. (1983) provided evidence that subThis research was supported by NSF Grant IST-8308670. We thank Doug Medin, Ed Shoben, Gordon Logan, and Dedre Gentner for discussions about this research. We also thank Robert Weisberg, Edward Bowden, and an anonymous reviewer for their helpful reviews, and Marna Smith for help in conducting and analyzing the experiments. Address correspondence and requests for reprints to Brian H. Ross, Department of Psychology, University of lllinois, 603 E. Daniel, Champaign, IL 61820. jects who are un...