This article reports the results of a meta-analysis using 50 experimental studies (256 effect sizes) of the overjustification effect. In general, we found support for the effect across age, dependent measure, and design type in specific situations where it is predicted to occur. Findings are less supportive of the theory for situations where there should be no difference between experimental and control groups (e.g. non-contingent or unexpected reward). Suggestions for future research are made.

different texts. The authors found that students with text and illustrations and students who generated their own illustrations performed better on a problem-solving test than students with text only and that there were no significant differences in performance between the former 2 groups.

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This study extends research by Glenberg, Sanocki, Epstein, and Morris (198 7) by suggesting that the accuracy of students' comprehension-monitoring self-assessments can be improved if they read expository text that contains illustrative examples and embedded questions. Students were asked to read text under different study conditions. It is argued that examples and embedded questions provide students with an opportunity to test their own level of understanding of passage content and, therefore, result in more accurate self-assessments of comprehension than does plain text. Students who read text with both examples and questions assessed their own comprehension more accurately than did students reading plain text. These students also made more accurate posttest predictions of test performance. It appears that active self-testing improves one's calibration of comprehension.

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