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A Meta-analysis of the Effectiveness of Intervention Programs Designed to Support Autonomy

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Abstract

The twofold purpose of the present study was, first, to determine whether training intervention programs designed to help people support the autonomy of others are effective and, second, to identify the set of conditions that allowed these interventions to be most effective. A meta-analysis of the findings from 19 studies with 20 effect sizes showed that the training programs were, overall, effective with a weighted effect size of 0.63. Moderator analyses of the overall effect size showed that the relatively more effective intervention programs were structured in ways that trained multiple elements of autonomy support and were presented in relatively brief (1–3 h) sessions in a laboratory training setting that focused on skill-based activities and utilized multiple types of media to deliver its content. Furthermore, relatively effective intervention programs were offered to teachers (rather than to other professionals), trainees (rather than to experienced professionals), and individuals with an autonomy (rather than a control) causality orientation. Though the small number of included studies warrants caution, results generally affirmed the effectiveness of autonomy-supportive training programs and identified the conditions under which future programs can be designed to be highly effective.

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Notes

  1. The 18 articles included 19 independent studies because the Williams et al. (1999) investigation included two independent intervention studies. The 19 independent studies included 20 effect sizes because the deCharms (1976) investigation reported separate effect sizes for the seventh and eighth grade classes.

  2. The deCharms (1976) study was published as a book. However, deCharms published the key findings from the same research project in a scholarly journal; see deCharms (1972). The full citation appears in the references.

  3. In one study (Williams and Deci 1996), we were unable to convert to an individual effect size because the results were reported as standardized beta coefficients with multiple predictors. Therefore, we relied on the point biserial correlation. For the causality orientation analysis in this same study, we coded the correlations between types of causality orientation and belief of autonomy-supportive care. Furthermore, both Reeve (1998) and Weber-Gasparoni (2003) had two experimental groups. For the purposes of the present meta-analysis, we used the data from only the autonomy support group and the control group, and we calculated effect sizes from the means and standard deviations for these two conditions. In Reeve (1998), both the immediate training effect and a longitudinal training effect were investigated; however, that study did not provide sufficient information on the longitudinal training effect to calculate that effect size (so only the immediate training effect was included in the present meta-analysis).

  4. Both Barch (2006) and Edmunds et al. (2008) reported separate results from students’ self-report data and from raters’ observation, while Reeve (1998) reported separate results from participants’ self-report data and from raters’ scoring of participants’ autonomy-supportive behavior. For the “type of dependent measure” moderator analysis, these separate effect sizes are shown in Table 6. For the overall meta-analysis, we computed and used a single overall effect size for each study by averaging the two effect sizes into a single composite.

  5. That is, effect sizes were weighted by sample sizes, corrected individually for artifacts, adjusted for sampling errors by weighting sample sizes across studies, corrected for positive bias of d value and reliabilities of dependent measures, and we adopted the formula Var(mean corrected d) = Var(d)/K to obtain the standard error of mean corrected d and its confidence intervals.

  6. In comparing the confidence interval from one subcategory to the confidence interval of another subcategory, it is possible for a confidence interval to be the same as the effect size (i.e., when the standard error of the mean corrected d is 0). In this case, we checked if the effect size for the subcategory fell outside the middle range of the confidence interval for the other subcategories.

  7. Even after dropping the large effect size of d = 5.759 associated with the Edmunds et al. (2008) study—5.759 is the average of 9.67 and 1.85 from the first and third columns in Table 6, the corrected observed effect size variance (\( {{{S_{\rm e}^2}} \left/ {{S_d^2}} \right.} \)) remained well below Hunter and Schmidt’s (2004) 75% rule with a percentage of variance of 40%. Hence, we are justified to continue to test for moderators even after removing the Edmunds et al. outlier effect size.

References

  • Assor, A., Kaplan, H., Feinberg, O., & Tal, K. (2009). Combining vision with voice: A learning and implementation structure promoting teachers’ internalization of practices based on self-determination theory. Theory and Research in Education, 7, 234–243. doi:10.1177/1477878509104328.

    Article  Google Scholar 

  • Assor, A., Kaplan, H., Kanat-Maymon, Y., & Roth, G. (2005). Directly controlling teacher behaviors as predictors of poor motivation and engagement in girls and boys: The role of anger and anxiety. Learning and Instruction, 15, 397–413. doi:10.1016/j.learninstruc.2005.07.008.

    Article  Google Scholar 

  • Assor, A., Kaplan, H., & Roth, G. (2002). Choice is good, but relevance is excellent: Autonomy-enhancing and suppressing teaching behaviors predicting students’ engagement in schoolwork. The British Journal of Educational Psychology, 27, 261–278. doi:10.1348/000709902158883.

    Article  Google Scholar 

  • Assor, A., Roth, G., & Deci, E. L. (2004). The emotional costs of perceived parental conditional regard: A self-determination theory analysis. Journal of Personality, 72, 47–87. doi:10.1111/j.0022-3506.2004.00256.x.

    Article  Google Scholar 

  • *Barch, J. (2006). From teachers’ autonomy supportiveness training to students’ intrinsic motivation. Paper presented at the Annual Meeting of the American Psychological Association, New Orleans, LA, August.

  • *Chatzisarantis, N. L., & Hagger, M. S. (2009). Effects of an intervention based on self-determination theory on self-reported leisure-time physical activity participation. Psychology and Health, 24, 29–48. doi:10.1080/08870440701809533.

    Article  Google Scholar 

  • *Cheon, S. H., & Moon, I. S. (2010). Implementing an autonomy-supportive fitness program to facilitate students’ autonomy and engagement. Korean Journal of Sport Psychology 21(1), 175–195.

    Google Scholar 

  • Clifford, M. M. (1990). Students need challenge, not easy success. Educational Leadership, 48, 22–26.

    Google Scholar 

  • Cohen, J. (1988). Statistical power analysis for the behavioral sciences. Hillsdale: Erlbaum.

    Google Scholar 

  • *Collins, R. (2001). Teachers' motivating styles and educational change. Dissertation Abstracts International, 61(9-A), 3463. UMI No. AAI9986787

    Google Scholar 

  • Cordova, D. I., & Lepper, M. R. (1996). Intrinsic motivation and the process of learning: Beneficial effects of contextualization, personalization, and choice. Journal of Educational Psychology, 88, 715–730. doi:10.1037/0022-0663.88.4.715.

    Article  Google Scholar 

  • *deCharms, R. (1972). Personal causation training in the schools. Journal of Applied Social Psychology, 2, 95–113. doi:10.1111/j.1559-1816.1972.tb01266.x.

    Article  Google Scholar 

  • *deCharms, R. (1976). Enhancing motivation: Change in the classroom. New York: Irvington.

    Google Scholar 

  • Deci, E. L. (2009). Large-scale school reform as viewed from the self-determination theory perspective. Theory and Research in Education, 7, 244–252. doi:10.1177/1477878509104329.

    Article  Google Scholar 

  • Deci, E. L., Eghrari, H., Patrick, B. C., & Leone, D. (1994). Facilitating internalization: The self-determination theory perspective. Journal of Personality, 62, 119–142. doi:10.1111/1467-6494.ep9406221281.

    Article  Google Scholar 

  • Deci, E. L., & Ryan, R. M. (1985). Intrinsic motivation and self-determination in human behavior. New York: Plenum.

    Google Scholar 

  • Deci, E. L., & Ryan, R. M. (2008). Favoriser la motivation optimale et la santé mentale dans les divers milieux de vie. Canadian Psychology, 49, 14–23. doi:10.1037/0708-5591.49.1.24.

    Google Scholar 

  • *Edmunds, J., Ntoumanis, N., & Duda, J. L. (2008). Testing a self-determination theory-based teaching style intervention in the exercise domain. European Journal of Social Psychology, 38(2), 375–388. doi:10.1002/ejsp.463.

    Article  Google Scholar 

  • Felner, R. D., Seitsinger, A. M., Brand, S., Burns, A., & Bolton, N. (2007). Creating small learning communities: Lessons from the project on high-performing learning communities about “what works” in creating productive, developmentally enhancing, learning contexts. Educational Psychologist, 42(4), 209–221. doi:10.1080/00461520701621061.

    Google Scholar 

  • Fisher, R. A. (1956). Statistical methods and scientific inference. Edinburgh: Oliver and Boyd.

    Google Scholar 

  • Furrer, C., & Skinner, E. A. (2003). Sense of relatedness as a factor in children’s academic engagement and performance. Journal of Educational Psychology, 95, 148–162. doi:10.1037/0022-0663.95.1.148.

    Article  Google Scholar 

  • Gagné, M., & Deci, E. L. (2005). Self-determination theory and work motivation. Journal of Organizational Behavior, 26(4), 331–362. doi:10.1002/job.322.

    Article  Google Scholar 

  • Gottfried, A. E., Fleming, J. S., & Gottfried, A. W. (1994). Role of parental motivational practices in children’s academic intrinsic motivation and achievement. Journal of Educational Psychology, 86, 104–113. doi:10.1037/0022-0663.86.1.104.

    Article  Google Scholar 

  • Grolnick, W. S. (2003). The psychology of parental control: How well-meant parenting backfires. Mahwah, NJ: Erlbaum.

    Google Scholar 

  • Grolnick, W. S., & Apostoleris, N. H. (2002). What makes parents controlling? In E. L. Deci & R. M. Ryan (Eds.), Handbook of self-determination research (pp. 161–181). Rochester: University of Rochester Press.

    Google Scholar 

  • Grolnick, W. S., Gurland, S. T., DeCourcey, W., & Jacob, K. (2002). Antecedents and consequences of mothers’ autonomy support: An experimental investigation. Developmental Psychology, 38, 143–155. doi:10.1037/0012-1649.38.1.143.

    Article  Google Scholar 

  • Grolnick, W. S., & Slowiaczek, M. L. (1994). Parents’ involvement in children’s schooling: A multidimensional conceptualization and motivational model. Child Development, 65(1), 237–252. doi:10.1111/1467-8624.ep9406130692.

    Article  Google Scholar 

  • Guay, F., Ratelle, C. F., & Chanal, J. (2008). Optimal learning in optimal contexts: The role of self-determination in education. Canadian Psychology, 49(3), 233–240. doi:10.1037/a0012758.

    Google Scholar 

  • Hall, S. M., & Brannick, M. T. (2002). Comparison of two random effects methods of meta-analysis. The Journal of Applied Psychology, 87, 377–389. doi:10.1037/0021-9010.87.2.377.

    Article  Google Scholar 

  • Halvari, A. E. M., & Halvari, H. (2006). Motivational predictors of change in oral health: An experimental test of self-determination theory. Motivation and Emotion, 30(4), 295–306. doi:10.1007/s11031-006-9035-8.

    Article  Google Scholar 

  • *Hardré, P., & Reeve, J. (2009). Benefits of training corporate managers to adopt a more autonomy-supportive style toward employees: an intervention study. International Journal of Training and Development, 13(3), 165–184. doi:10.1111/j.1468-2419.2009.00325.x.

    Article  Google Scholar 

  • Hedges, L. V., & Vevea, J. L. (1998). Fixed- and random-effects models in meta-analysis. Psychological Methods, 3, 486–504. doi:10.1037/1082-989X.3.4.486.

    Article  Google Scholar 

  • Hodgins, H. S., & Knee, C. R. (2002). The intergrating self and conscious experience. In E. L. Deci & R. M. Ryan’s (Eds.), Handbook of self-determination theory research (pp. 87–100). Rochester: University of Rochester Press.

    Google Scholar 

  • Hoyt, W. T. (2000). Rater bias is psychological research: When it is a problem and what we can do about it? Psychological Methods, 5, 64–86. doi:10.1037/1082-989X.5.1.64.

    Article  Google Scholar 

  • Hunter, J. E., & Schmidt, F. L. (2000). Fixed effect vs. random effects meta-analysis models: Implications for cumulative knowledge in psychology. International Journal of Selection and Assessment, 8, 275–292. doi:10.1111/1468-2389.00156.

    Article  Google Scholar 

  • Hunter, J. E., & Schmidt, F. L. (2004). Methods of meta-analysis: Correcting error and bias in research findings (2nd ed.). Thousand Oaks: Sage.

    Google Scholar 

  • Jang, H. (2008). Supporting students’ motivation, engagement, and learning during an uninteresting activity. Journal of Educational Psychology, 100, 798–811. doi:10.1037/a0012841.

    Article  Google Scholar 

  • Koestner, R., Ryan, R. M., Bernieri, F., & Holt, K. (1984). Setting limits on children’s behavior: The differential effects of controlling versus informational styles on intrinsic motivation and creativity. Journal of Personality, 52, 233–248. doi:10.1111/j.1467-6494.1984.tb00879.x.

    Article  Google Scholar 

  • Le, H., Schmidt, F. L., Harter, J., & Lauver, K. (2010). The problem of empirical redundancy of constructs in organizational research: An empirical investigation. Organizational Behavior and Human Decision Processes, 112, 112–125. doi:10.1016/j.obhdp.2010.02.003.

    Article  Google Scholar 

  • Le, H., Schmidt, F. L., & Putka, D. J. (2009). The multi-faceted nature of measurement error and its implications for measurement error corrections. Organizational Research Methods, 12, 165–200. doi:10.1177/1094428107302900.

    Article  Google Scholar 

  • Mageau, G. A., & Vallerand, R. J. (2003). The coach–athlete relationship: A motivational model. Journal of Sports Sciences, 21(11), 883–904. doi:10.1080/0264041031000140374.

    Article  Google Scholar 

  • *Moss, J. (2009). Autonomy support and engagement in prekindergarten: Supporting the teachers in traditional and Montessori environments. Unpublished Master’s thesis, University of Wisconsin–Milwaukee.

  • Pelletier, L. G., Seguin-Levesque, C., & Legualt, L. (2002). Pressure from above and pressure from below as determinants of teachers’ motivation and teaching behaviors. Journal of Educational Psychology, 94, 186–196. doi:10.1037/0022-0663.94.1.186.

    Article  Google Scholar 

  • Perry, N. E. (1998). Young children’s self-regulated learning and the contexts that support it. Journal of Educational Psychology, 90, 715–729. doi:10.1037/0022-0663.90.4.715.

    Article  Google Scholar 

  • Pomerantz, E. M., & Eaton, M. M. (2001). Maternal intrusive support in the academic context: Transactional socialization process. Developmental Psychology, 37(2), 174–186. doi:10.1037/0012-1649.37.2.174.

    Article  Google Scholar 

  • *Reeve, J. (1998). Autonomy support as an interpersonal motivating style: Is it teachable? Contemporary Educational Psychology, 23(3), 312–330. doi:10.1006/ceps.1997.0975.

    Article  Google Scholar 

  • Reeve, J. (2009). Why teachers adopt a controlling motivating style toward students and how they can become more autonomy supportive. Educational Psychologist, 44(3), 159–175. doi:10.1080/00461520903028990.

    Article  Google Scholar 

  • Reeve, J., Deci, E. L., & Ryan, R. M. (2004a). Self-determination theory: A dialectical framework for understanding the sociocultural influences on student motivation. In D. McInerney & S. Van Etten (Eds.), Research on sociocultural influences on motivation and learning: Big theories revisited (Vol. 4, pp. 31–60). Greenwich: Information Age Press.

    Google Scholar 

  • Reeve, J., & Jang, H. (2006). What teachers say and do to support students’ autonomy during a learning activity. Journal of Educational Psychology, 98, 209–218. doi:10.1037/0022-0663.98.1.209.

    Article  Google Scholar 

  • *Reeve, J., Jang, H., Carrell, D., Barch, J., & Jeon, S. (2004b). Enhancing high school students’ engagement by increasing their teachers’ autonomy support. Motivation and Emotion, 28(2), 147–169. doi:10.1023/B:MOEM.0000032312.95499.6f.

    Article  Google Scholar 

  • Reeve, J., Jang, H., Hardré, P., & Omura, M. (2002). Providing a rationale in an autonomy-supportive way as a strategy to motivate others during an uninteresting activity. Motivation and Emotion, 26, 183–207. doi:10.1023/A:1021711629417.

    Article  Google Scholar 

  • Reeve, J., Nix, G., & Hamm, D. (2003). Testing models of the experience of self-determination in intrinsic motivation and the conundrum of choice. Journal of Educational Psychology, 95, 375–392. doi:10.1037/0022-0663.95.2.375.

    Article  Google Scholar 

  • Rosenthal, R. (1987). Judgment studies: Design, analysis, and meta-analysis. New York: Cambridge University Press.

    Book  Google Scholar 

  • Ryan, R. M. (1982). Control and information in the intrapersonal sphere: An extension of cognitive evaluation theory. Journal of Personality and Social Psychology, 43, 450–461. doi:10.1037/0022-3514.43.3.450.

    Article  Google Scholar 

  • Ryan, R. M., & Deci, E. L. (2000). Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. The American Psychologist, 55(1), 68–78. doi:10.1037/0003-066X.55.1.68.

    Article  Google Scholar 

  • Ryan, R. M., & Deci, E. L. (2002). An overview of self-determination theory: An organismic-dialectical perspective. In E. L. Deci & R. M. Ryan (Eds.), Handbook of self-determination research (pp. 3–33). Rochester: University of Rochester Press.

    Google Scholar 

  • Ryan, R. M., & Deci, E. L. (2008). A self-determination approach to psychotherapy: The motivational basis for effective change. Canadian Psychology, 49(3), 186–193. doi:10.1037/a0012753.

    Google Scholar 

  • Ryan, R. M., & Grolnick, W. S. (1986). Origins and pawns in the classroom: Self-report and projective assessments of individual differences in children’s perceptions. Journal of Personality and Social Psychology, 50, 550–558. doi:10.1037/0022-3514.50.3.550.

    Article  Google Scholar 

  • Sagie, A. (1993). Detecting moderators with meta-analysis: An evaluation and comparison of techniques. Personnel Psychology, 46(3), 629. doi:10.1111/j.1744-6570.1993.tb00888.x.

    Article  Google Scholar 

  • Schmidt, F. L. (2010). Detecting and correcting the lies that data tell. Perspectives on Psychological Science, 5, 233–242. doi:10.1177/1745691610369339.

    Article  Google Scholar 

  • Schmidt, F. L., & Hunter, J. E. (1999). Theory testing and measurement error. Intelligence, 27, 183–198. doi:10.1016/S0160-2896(99)00024-0.

    Article  Google Scholar 

  • Schmidt, F. L., & Hunter, J. E. (2003). History, development, evolution, and impact of validity generalization and meta-analysis methods, 1975–2001. In K. R. Murphy (Ed.), Validity generalization: A critical review (pp. 31–66). Mahwah: Lawrence Erlbaum.

    Google Scholar 

  • Schmidt, F. L., & Le, H. A. (2005). Hunter & Schmidt meta-analysis programs (version 1.1) [Computer software].

  • Schraw, G., & Lehman, S. (2001). Situational interest: A review of the literature and directions for future research. Educational Psychology Review, 13, 23–52. doi:10.1023/A:1009004801455.

    Article  Google Scholar 

  • Schulze, R. (2004). Meta-analysis: A comparison of approaches. Cambridge: Hogrefe & Huber.

    Google Scholar 

  • Sullivan, G. S. (2005). The effects of a coaching education workshop on the self-regulated motivation of 6th-grade male and female basketball players. Dissertation Abstracts International, 66(5-B), 2850. UMI No. AAI3176402.

    Google Scholar 

  • *Tessier, D., Sarrazin, P., Ntoumanis, N. (2008). The effects of an experimental programme to support students’ autonomy on the overt behaviours of physical education teachers. European Journal of Psychology of Education, 23(3), 239–253. doi:10.1007/BF03172998.

    Article  Google Scholar 

  • Vansteenkiste, M., Simons, J., Lens, W., Sheldon, K. M., & Deci, E. L. (2004). Motivating learning, performance, and persistence: The synergistic role of intrinsic goals and autonomy-support. Journal of Personality and Social Psychology, 87, 246–260. doi:10.1037/0022-3514.87.2.246.

    Article  Google Scholar 

  • Vansteenkiste, M., Simons, J., Lens, W., Soenens, B., & Matos, L. (2005). Examining the impact of extrinsic versus intrinsic goal framing and internally controlling versus autonomy-supportive communication style upon early adolescents’ academic achievement. Child Development, 76, 483–501. doi:10.1111/j.1467-8624.2005.00858.x.

    Article  Google Scholar 

  • *Weber-Gasparoni, K. (2003). An innovative psychoeducational method and early childhood caries prevention. Unpublished doctoral dissertation, University of Iowa.

  • Williams, G. C. (2002). Improving patients’ health through supporting the autonomy of patients and providers. In E. L. Deci & R. M. Ryan (Eds.), Handbook of self-determination research (pp. 233–254). Rochester: University of Rochester Press.

    Google Scholar 

  • *Williams, G. C., Cox, E. M., Kouides, R., & Deci, E. L. (1999). Presenting the facts about smoking to adolescents: The effects of an autonomy supportive style. Archives of Pediatrics and Adolescent Medicine, 153, 959–964. doi:10.1001/archpedi.153.9.959.

    Google Scholar 

  • *Williams, G. C., & Deci, E. L. (1996). Internalization of biopsychosocial values by medical students: A test of self-determination theory. Journal of Personality and Social Psychology, 70(4), 767–779. doi:10.1037/0022-3514.70.4.767.

    Article  Google Scholar 

  • *Williams, G. C., Gagné, M., Ryan, R. M., & Deci, E. L. (2002). Facilitating autonomous motivation for smoking cessation. Health Psychology, 21, 40–50. doi:10.1037/0278-6133.21.1.40.

    Article  Google Scholar 

  • Williams, G. C., Lynch, M. F., McGregor, H. A., Ryan, R. M., Sharp, D., & Deci, E. L. (2006a). Validation of the “important other” climate questionnaire: Assessing autonomy support for health-related change. Families, Systems, & Health, 24(2), 179–194. doi:10.1037/1091-7527.24.2.179.

    Article  Google Scholar 

  • *Williams, G. C., McGregor, H., Sharp, D., Levesque, C. S., Kouides, R. W., Ryan, R. M. et al. (2006b). Testing a self-determination theory intervention for motivating tobacco cessation: Supporting autonomy and competence in a clinical trial. Health Psychology, 25, 91–101. doi:10.1037/0278-6133.25.1.91.

    Article  Google Scholar 

  • Zuckerman, M., Porac, J., Lathin, D., Smith, R., & Deci, E. L. (1978). On the importance of self-determination for intrinsically-motivated behavior. Personality and Social Psychology Bulletin, 4, 443–446. doi:10.1177/014616727800400317.

    Article  Google Scholar 

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Acknowledgment

We express our thanks to Frank L. Schmidt for help in the interpretation of the meta-analytic results. This research was supported by the WCU (World Class University) Program founded by the Korean Ministry of Education, Science and Technology, consigned to the Korea Science and Engineering Foundation (grant no. R32-2008-000-20023-0).

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  1. Department of Psychological and Quantitative Foundations, University of Iowa, 361 Lindquist Center, Iowa City, IA, 52242, USA

    Yu-Lan Su

  2. Korea University, Seoul, South Korea

    Johnmarshall Reeve

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References marked with an asterisk (including Froiland, J. M., under review. Strengthening the intrinsic motivation of children through parental autonomy support and student intrinsic learning goals, manuscript under review; Weber-Gasparoni, K., in preparation. Effectiveness of a psychoeducational intervention for early childhood caries prevention. Paper in preparation, University of Iowa, cited in the text) indicate studies included in the meta-analysis.

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Su, YL., Reeve, J. A Meta-analysis of the Effectiveness of Intervention Programs Designed to Support Autonomy. Educ Psychol Rev 23, 159–188 (2011). https://doi.org/10.1007/s10648-010-9142-7

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