We wish to thank Susan Chipman, Albert
Corbett, Ken Koedinger, Rich Lehrer, Marsha Lovett, Melvin Reder, and Steve
Ritter for their comments on this paper. This is not to imply, however, that
any of these individuals agree with all of the assertions in the paper.
Preparation of this paper was supported by grant MDR-92-53161 from the NSF
Directorate for Education and Human Resources.
 Indeed, much of the research and theory in
information-processing psychology concerns subjects' misrepresentation of