The Cognitive Science Laboratory of the University of Southern California has conducted a series of studies on the experimental effects of motivation on a low-stakes (to the student) standardized test. This report summarizes these studies and their results. The test in question is the National Assessment of Educational Progress (NAEP). A series of studies in 1992 investigated the effects of various motivational conditions on the performance of 8th and 12th graders on a subset of items from the NAEP 1990 mathematics test. Several pilot studies were conducted first to select the motivational conditions that might influence performance. The main study compared the effects of financial reward, competition, personal accomplishment, and standard NAEP test instructions on mathematics performance. Results indicate that financial reward can improve the performance of eighth graders. In the 12th grade, no differences were observed among the conditions. The eighth grade findings indicate that test developers may be underestimating the achievement of students when scores on low stakes tests are used as the indicators of achievement. Five appendixes discuss study methodology, instructions, and detailed results. (Contains 93 tables, 103 appendix tables, and 65 references.) (SLD)