Self-determination theory
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Self-determination theory (SDT) is a general theory of human motivation and is concerned with the choices people make with their own free will and full sense of choice, without any external influence and interference. For example, a self-determined person chooses to behave in a manner that reflects his autonomy and his behavior is not to achieve an external reward or escape aversive stimuli in the environment. In simple terms, SDT focuses on the degree to which an individual’s behavior is self-endorsed and self-determined (Deci & Ryan, 2002).
In the 1970s, research on SDT evolved from studies comparing the intrinsic and extrinsic motives, and the dominant role extrinsic motivation played in an individual’s behavior (e.g. Lepper, Greene, & Nisbett, 1973) but it was not until mid 1980s that SDT was formally introduced and accepted as a sound empirical theory (Deci & Ryan, 2008). Research applying SDT to different areas in social psychology has increased considerably during the last decade.
Key studies that led to emergence of SDT included research on intrinsic motivation (e.g. Deci, 1971). Intrinsic motivation refers to initiating an activity for its own sake because it is interesting and satisfying in itself, as opposed to doing an activity to obtain an external goal (extrinsic motivation). Different types of motivations have been described based on the degree they have been internalized. Internalization refers to active attempt to transform an extrinsic motive into personally endorsed values and thus assimilate behavioral regulations that were originally external (Ryan, 1995). Based on the degree of control exerted by external factors, levels of extrinsic motivation can be aligned along a continuum (Ryan & Deci, 2000). On the low-end of the continuum is external regulation, which refers to doing something for the sole purpose of achieving a reward or avoiding a punishment, followed by introjected regulation. Introjected regulation refers to partial internalization of extrinsic motives. Next is identified regulation, which refers to doing an activity because the individual identifies with the values and accepts it as his own. Therefore, identified regulation is autonomous and not merely controlled by external factors. Finally, integrated regulation refers to identification with the values and meanings of the activity to the extent that it becomes fully internalized and autonomous (Ryan & Deci, 2000).
Deci and Ryan later expanded on the early work differentiating between intrinsic and extrinsic motivation and proposed three main intrinsic needs (Deci & Ryan, 1991, 1995) involved in self-determination. According to Deci and Ryan, the three psychological needs motivate the self to initiate behavior and specify nutriments that are essential for psychological health and well-being of an individual. These needs are said to be universal, innate and psychological and include the need for competence, need for autonomy and the need for relatedness (Deci & Ryan, 2002).
- Need for competence: refers to the need to experience oneself as capable and competent in controlling the environment and being able to reliably predict outcomes.
- Need for autonomy (or self-determination): refers to the need to actively participate in determining own behavior. It includes the need to experience one’s actions as result of autonomous choice without external interference.
- Need for relatedness: refers to need to care for and be related to others. It includes the need to experience authentic relatedness from others and to experience satisfaction in participation and involvement with the social world (Deci & Ryan).
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[edit] Key Studies
Deci (1971): external rewards on intrinsic motivation
Deci investigated the effects of external rewards on intrinsic motivation in two laboratory and one field experiment. Based on the results from earlier animal and human studies regarding intrinsic motivation the author explored two possibilities. In the first two experiments he looked at the effect of extrinsic rewards in terms of a decrease in intrinsic motivation to perform a task. Earlier studies showed contradictory or inconclusive findings regarding decrease in performance on a task following an external reward. The third experiment was based on findings of developmental learning theorists and looked at whether a different type of reward enhances intrinsic motivation to participate in an activity.
Experiment I tested the hypothesis that if an individual is intrinsically motivated to perform an activity, introduction of an extrinsic reward decreases the degree of intrinsic motivation to perform the task. Twenty-four undergraduate psychology students participated in the first laboratory experiment. The participants were assigned to experimental (N=12) and control group (N = 12). Each group participated in 3 sessions conducted on three different days. During the sessions the participants were engaged in working on a puzzle which was assumed to be an activity that college students would be intrinsically motivated to do. The puzzle could be put together to form numerous different configurations. In each session, the participants were shown 4 different configurations drawn on a piece of paper and were asked to use the puzzle to reproduce the configurations while they were being timed. The experimental condition was identical to control, except for the second session where the participants in the experimental condition were given a dollar for completing each puzzle within time. The first and third session was identical and no money was provided to any group for task completion. During the middle of each session, the experimenter left the room for eight minutes and the participants were told that they were free to do whatever they wanted during that time. Thus, the participants were free to read magazines present in the room, work on the puzzle or do whatever they liked during the 8 minute interval while the experimenter observed during that period. The amount of time spent working on the puzzle during the free choice period was used to measure motivation. Also, at the end of the experiment, they were asked to rate if they found the experiment interesting or not. As Deci expected, when external reward was introduced during session two, the participants spent more time working on the puzzles during the free choice period in comparison to session 1 and when the external reward was removed in the third session, the time spent working on the puzzle dropped lower than the first session. All subjects reported finding the task interesting and enjoyable at the end of each session, providing evidence for the experimenter’s assumption that the task was intrinsically motivating for the college students. The study showed some support of the experimenter’s hypothesis and a trend towards decrease in intrinsic motivation was seen after money was provided to the participants as external reward.
The field experiment (Experiment II) was similar to laboratory Experiment I, but was conducted in a natural setting. Eight student workers were observed at college biweekly newspaper. Four of the students served as a control group and worked on Friday publication of the newspaper, where as the experimental group comprised of students who worked on Tuesdays. The control and experimental group students were not aware that they were being observed. The 10 week observation was divided into 3 time periods. The task in this study required the students to write headlines for the newspaper. Time I and Time II were identical for both groups. However, the students in experimental group were given 50 cents for each headline they wrote during Time II. At the end of Time II, they were told that in the future the newspaper cannot pay them 50 cent for each headline anymore as the newspaper ran out of the money allocated for that and they were not paid for the headlines during Time III. The speed of task completion (headlines) was used as a measure of motivation in this experiment. Absences were used as a measure of attitudes. In order to assess the stability of the observed effect, the experimenter observed the students again (Time IV) for two weeks. There was a gap of 5 weeks between Time III and Time IV. Due to absences and change in assignment etc., motivation data was not available for all students. The results of this experiment were similar to Experiment I and monetary reward was found to decrease the intrinsic motivation of the students, thus providing some support to the hypothesis proposed by Deci.
Experiment III was conducted in laboratory and was identical to Experiment I in all respects except for the kind of external reward provided to the students in experimental condition during Session 2. In this experiment, verbal praise was used as an extrinsic reward. The experimenter hypothesized that a different type of reward, i.e. social approval in form of verbal reinforcement and positive feedback for performing the task that a person is intrinsically motivated to perform will enhance the degree of internal motivation even after the extrinsic reward is removed. The results of the experiment III confirmed the hypothesis and the students’ performance increased significantly during the third session (when verbal praise and positive feedback was provided as an external reward) in comparison to the session one, showing that verbal praise and positive feedback enhances performance in tasks that a person is initially intrinsically motivated to perform, providing an evidence that verbal praise as external reward increases intrinsic motivation. The author explained differences between the two types of external rewards as having different effects on intrinsic motivation. When a person is intrinsically motivated to perform a task and money is introduced to work on the task, the individual cognitively re-evaluates the importance of the task and the intrinsic motivation to perform the task (because the individual finds it interesting) shifts to extrinsic motivation and the primary focus changes from enjoying the task to gaining financial reward. However, when verbal praise is provided in a similar situation increases intrinsic motivation as it is not evaluated to be controlled by external factors and the person sees the task as an enjoyable task that is performed autonomously. The increase in intrinsic motivation is explained by positive reinforcement and an increase in perceived locus of control to perform the task.
Pritchard, Campbell and Campbell (1975): Evaluation of Deci's Hypothesis
Pritchard, Campbell and Campbell conducted a similar study to evaluate Deci’s hypothesis regarding the role of extrinsic rewards on decreasing intrinsic motivation. Participants were randomly assigned to two groups. A chess-problem task was used in this study. Data was collected in two sessions. During the first session, after the experiment went briefed the participants regarding the chess-problem task, the participants answered a background questionnaire that included questions on the amount of time the participant played chess during the week, the number of years that the participant has been playing chess for, amount of enjoyment the participant gets from playing the game, etc. The participants in both groups were then told that the experimenter needed to enter the information in the computer and for the next ten minutes the participant were free to do whatever they liked. The experimenter left the room for ten minutes. The room had similar chess-problem tasks on the table, some magazines as well as coffee was made available for the participants if they chose to have it. The time spent on the chess-problem task was observed through a one way mirror by the experimenter during the ten minutes break and was used as a measure of intrinsic motivation. After the experimenter returned, group 1 was told that there was a monetary reward for the participant who could work on the most chess problems in the given time. Group 2 was not offered a monetary reward. Group 1 was also told that the reward is for this session only and would not be offered during the next session. The two groups were then given packets containing the task to work on. The second session was the same for the two groups. After a filler task, the experimenter left the room for 10 minutes and the time participants spent on the chess-problem task was observed. Group 1 was reminded that there was no reward for the task this time. Both groups worked on the task after the experimenter returned and the participants worked on the chess-problem task. After both sessions the participants were required to respond to questionnaires evaluating the task, i.e. to what degree did they find the task interesting. Both groups reported that they found the task interesting. The results of the study showed that the paid group showed a significant decrease in time spent on chess-problem task during 10 minute free time from session 1 to session 2 in comparison to the group that was not paid, thus confirming the hypothesis presented by Deci (1971) that contingent monetary reward for an activity decreases the intrinsic motivation to perform that activity. Other studies were conducted around this time focusing at other types or rewards as well as other external factors that play a role in decreasing intrinsic motivation (e.g. Amabile, DeJong, & Lepper, 1976; Lepper & Greene, 1975).
Sook Ning Chua and Richard Koestner (2008): SDT and Solitude
Sook Ning Chua and Richard Koestner explored the consequences of activities done in solitude. They argued that relation of solitary activities to feelings of loneliness and life satisfaction depends on whether individuals feel autonomous rather than controlled about spending time alone. Previous researchers have demonstrated the association of autonomy with adaptive outcomes, but no study has examined the relative autonomy of solitary behavior. In all, 108 participants reported the percentage of waking time they spent in solitude per day and completed measures of attachment styles, motivation for solitary activities, loneliness, and well-being. This study is the first to explore solitary behavior from the framework of self-determination theory. Other SDT studies are beginning to focus on motivation for negative action or the absence of action. This study looked at one's motivation not to socialize with others and instead remain in solitude. In support of SDT, the results suggest that relative autonomy is important regardless of one's decision to act or not to act. The results also emphasize the importance of autonomous social behavior. (Sook Ning Chua, Richard Koestner, 2008).
[edit] Theoretical Basis of SDT
SDT comprises of 4 mini-theories (Deci & Ryan, 2002). These theories are:
[edit] Cognitive Evaluation Theory
Cognitive Evaluation Theory (CET) looks at how contextual factors effect intrinsic motivation. The theory maintains that basic psychological needs for autonomy and competency are major factors in intrinsic motivation and the degree to which contextual factors (rewards, punishments, deadlines etc.) effect intrinsic motivation depends on whether these contextual factors support or thwart attainment of the basic psychological needs. Specifically, cognitive evaluation theory proposes that external events have two kinds of effects on intrinsic motivation. Deci & Ryan (2002) described Perceived Locus of Causality (PLOC) and Perception of Competence as the two primary cognitive aspects of contextual events that affect intrinsic motivation. The Perceived Locus of Causality is strongly impacted by the need for autonomy. Intrinsic motivation is said to be undermined when a contextual event prompts a change towards a more external locus of causality (E-PLOC). Conversely, when an events a prompt towards Internal Locus of Causality (I-PLOC), intrinsic motivation is enhanced (Deci & Ryan). The second cognitive process, perceived competence is strongly related to the need for competence. When a contextual event increases the perceived self competence, it enhances the individual’s intrinsic motivation (Deci & Ryan).
CET also differentiates between the controlling and informational aspects of contextual event or environment (Deci & Ryan, 2002). The controlling aspect refers to factors in the social environment that exert pressure towards specified outcomes, thus producing a shift towards a more external perceived locus of causality; whereas the informational aspect refers to informational events and communications that provide feedback regarding an individual’s performance and thus plays an important role in an individual’s experience of competent engagement in an activity (Deci & Ryan).
[edit] Organismic Integration Theory
It has been generally presumed that extrinsic motivation is nonautonomous. However, Deci and Ryan (2002) propose that it is possible for an individual to be autonomously extrinsically motivated and the research on Organismic Integration Theory (OIT) proposes that activities endorsed by significant others, social group etc. that an individual is not intrinsically motivated to perform are internalized and integrated with sense of self. The degree to which the internalization and integration takes place determines the level of autonomy in extrinsically motivated behavior. OIT conceptualizes internalization along a continuum. Thus, the more an event or activity is internalized or integrated with sense of self, the more the experienced sense of autonomy in engaging in the event or activity (Deci & Ryan). Based on the level of internalization or internal regulation, extrinsic motivation has been divided into different types (external regulation, introjected regulation, identified regulation), previously discussed in this article.
[edit] Causality Orientation Theory
Causality Orientation Theory looks at the role of individual differences in motivational orientations (Deci & Ryan, 2002). The individual differences in motivational orientations are shaped by an individual’s experiences with social context and inner resources developed as a result of these interactions. Causality Orientation focuses on the inner resources and the role they play in the current social context (Deci & Ryan). Deci & Ryan (1985) developed General Causality Orientation Scale (GCOS) which measures 3 types of motivational orientations based on the degree of self-determination involved when an individual engages in an experience or activity. These 3 types of motivational orientations are autonomy, controlled and impersonal orientations. All three types exist in all individuals, but the degree to which a person possesses each while engaging in a social context varies and these variations are relatively permanent. (GCOS is available at: http://www.psych.rochester.edu/SDT/measures/caus.html )
- Autonomy Orientation refers to regulation of behavior based on interest and self-endorsed values. Autonomy orientation indicates an individual’s general tendencies towards intrinsic and well-integrated extrinsic motives (Deci & Ryan, 2002).
- Controlled Orientation refers to regulation of behavior based on controls and directives regarding how a person should behave. Deci and Ryan relate controlled orientation to external and introjected regulation.
- Impersonal Orientation relates to amotivation and lack of intentional action (Deci & Ryan). It refers to unintentional behavior that lacks any motive.
[edit] Basic Needs Theory
Basic needs theory presents the concept of basic psychological needs (autonomy, competence and relatedness) and the role played by these needs in healthy development and functioning of an individual. Deci and Ryan (2002) describe autonomy, competence and relatedness as the fundamental nutriments for healthy development and well-being of an individual. An individual will develop and function in a healthy manner based on the extent these needs are satisfied or thwarted (Deci & Ryan).
[edit] New Developments
In recent years, expansion and development of various SDT concepts continue. Principles of SDT have been applied in many domains of life, e.g., job demands (Fernet, Guay, Senecal, 2004); parenting (e.g. Soenens, Vansteenkiste, Lens, Luyckx, Beyers, Goossens & Ryan, R. M. (2007); teaching (Roth, Assor, Kanat-Maymon & Kaplan, 2007) and health (e.g. Kennedy & Nollen, 2004) etc. Besides the domains mentioned above, self-determination theory research has been widely applied to the field of sports (e.g. Fortier, Sweet, O’Sullivan, & Williams, 2007). A recent study by Spanish researchers, Murcia, Roman, Galindo, Alonso and Gonzalez-Cutre (2008) looked at the influence of peers on enjoyment in exercise. Specifically, the researchers looked at the effect of motivational climate generated by peers on exercisers by analyzing data collected through questionnaires and rating scales. The assessment included evaluation of motivational climate, basic psychological needs satisfaction, levels of self determination and self-regulation (amotivation, external, introjected, identified and intrinsic regulation) and also the assessment of the level of satisfaction and enjoyment in exercising. Data analysis revealed that a climate, in which the peers are supportive and peers emphasize on cooperation, effort and personal improvement (task climate) influences variables like basic psychological needs, motivation and enjoyment, as well as adherence to exercise and sport programmes. The task climate positively predicted the three basic psychological needs (competence, autonomy and relatedness) and thus positively predicted self-determined motivation. Task climate and the resulting self-determination were also found to positively influence level of enjoyment the exercisers experienced during the activity (Murcia, Roman, Galindo, Alonso & Gonzalez-Cutre). Besides application of SDT to different fields, some of the topics in the contemporary research include research on mindfulness as it relates to autonomous functioning and the concept of vitality in self-regulation (Deci & Ryan, 2008).
Awareness has always been associated with autonomous functioning; however it was only recently that the SDT researchers incorporated the idea of mindfulness and its relationship with autonomous functioning and emotional wellbeing in their research (Brown & Ryan, 2003). Brown and Ryan conducted a series of 5 experiments to study mindfulness. They defined mindfulness as open, undivided attention to what is happening within as well as around oneself. One of the experiments (Experiment 4) specifically looked at the relationship between mindfulness, level of autonomy and wellbeing. For Experiment 4, 74 adult participants were recruited via newspaper ads from the community and 92 additional participants were recruited from introductory psychology classes. Mindful Attention Awareness Scale (MAAS) was administered to evaluate trait mindfulness. Participants were paged three times a day and they recorded what they were doing at the time they received the page for 21 consecutive days. Participants also completed a modified version of MAAS (consisted of five items to assess state mindfulness) and a short adjective checklist to assess affect valence. Baseline measures were previously taken. Participants also recorded the time lag between getting the page and filling out the forms. Pager notification occurred during three periods of the day and the contact times, which were randomly generated, were no closer together than two hours. The forms were returned daily and if deviations from the procedure were found, clarification was provided. Brown and Ryan found that trait mindfulness predicted more autonomous day-to-day activity and lower levels of unpleasant affect. Trait MAAS failed to predict pleasant affect for the daily moment-to-moment samples. Higher levels of autonomy, more intense and frequent pleasant affect, and less intense and less frequent unpleasant affect were associated with state mindfulness. State and trait mindfulness were found to be independent of one another. The authors concluded that when individuals act mindfully, their actions are consistent with their values and interest. Also, there is a possibility that being autonomous and performing an action because it is enjoyable to oneself increases mindful attention to one’s actions. The relationship found between mindfulness, self-regulation of behavior and psychological well-being of an individual suggests a new avenue for future research on SDT (Brown & Ryan).
Another area of interest for SDT researchers is relationship between vitality and self-regulation (see Ryan & Deci, 2008 for a detailed overview). Deci and Ryan (2008) define vitality as energy available to the self either directly or indirectly from basic psychological needs. This energy allows individuals to act autonomously. Deci and Ryan point out that many theorists have posited that self regulation depletes energy but SDT researchers have proposed and demonstrated that only controlled regulation depletes energy, autonomous regulation can be actually be vitalizing (e.g., Moller, Deci, & Ryan, 2006).
[edit] Education and Self-Determination Theory
There was a recent study done by Hyungshim Jang in which the capacity of two different theoretical models of motivation were used to explain why an externally provided rationale for doing a particular assignment often helps in a students' motivation, engagement, and learning during relatively uninteresting learning activities. One hundred thirty-six undergraduate students (108 women, 28 men) worked on a relatively uninteresting short lesson after either receiving or not receiving a rationale. Students who received the rationale showed greater interest, work ethic, and determination. (Hyungshim Jang, 2008).
Structural equation modeling was used to test three alternative explanatory models to understand why the rationale produced such benefits--an identified regulation model based on self-determination theory, an interest regulation model based on interest-enhancing strategies research, and an additive model that integrated both models. The data fit all three models; however, only the model based on self-determination theory helped students' engagement and therefore, their learning. Findings show the role that externally provided rationales can play in helping students generate the motivation they need individually to engage in and learn from uninteresting, but personally important, material. (Hyungshim Jang, 2008).
The importance of these findings to those in the field of education is that when teachers try to find ways to promote students' motivation during relatively uninteresting (but potentially important) learning activities, they can successfully do so by promoting the value of the task. One way teachers can help students value what they may deem "uninteresting" learning task is by providing a rationale that identifies the lesson's otherwise hidden value, helps students understand why the lesson is genuinely worth their effort, and communicates why the lesson can be expected to be useful to them. When successful, this strategy of instruction can aid in creating an opportunity for students to perceive, accept, and personally endorse the value of any learning activity. (Hyungshim Jang, 2008).
[edit] Self-Determination Theory and Alcohol Use
According to self-determination theory (Deci and Ryan, 1987), individuals that attribute their actions to external circumstances rather than internal mechanisms are far more likely to succumb to peer pressure. In contrast, individuals that consider themselves autonomous tend to be initiators of actions rather than followers. Research examining the relationship between self-determination theory and alcohol use among college students has indicated that individuals with the former criteria for decision making are associated with greater alcohol consumption and drinking as a function of social pressure. For instance, in a study conducted by Knee and Neighbors (2002), external factors in the individuals who claim to not be motivated by internal factors were found to be associated with drinking for extrinsic reasons, and with stronger perceptions of peer pressure, which in turn was related to heavier alcohol use. Given the evidence suggesting a positive association between a outward motivation and drinking, and the potential role of perceived social influence in this association, understanding the precise nature of this relationship seems important. Further, it may be hypothesized that the relationship between self-determination and drinking may be mediated to some extent by the perceived approval of others (Neharika Chawla, Clayton Neighbors, Diane Logan, Melissa A Lewis, Nicole Fossos. 2009)
[edit] References
- Amabile, T. M., DeJong, W., & Lepper, M. (1976). Effects of externally imposed deadlines on subsequent intrinsic motivation. Journal of Personality and Social Psychology, 34, 92–98.
- Brown, K. W., & Ryan, R. M. (2003). The benefits of being present: Mindfulness and its role in psychological well-being. Journal of Personality and Social Psychology, 84, 822–848.
- Chawla, N., Neighbors, C., Logan, D., Lewis, M.A., Fossos, N. (2009). Perceived Approval of Friends and Parents as Mediators of the Relationship Between Self-Determination and Drinking. Journal of Studies on Alcohol and Drugs, 70(1), 92-100.
- Chua, Sook Ning, Koestner, Richard. (2008). A Self-Determination Theory Perspective on the Role of Autonomy in Solitary Behavior. The Journal of Social Psychology, 148(5), 645-7.
- Deci, E., & Ryan, R.. (1985a). Intrinsic motivation and self-determination in human behavior. New York: Plenum.
- Deci, E, & Ryan, R (1985b). The general causality orientation scale. Self determination in personality. Journal of Research in Personality, 19, 109 – 134.
- Deci, E., & Ryan, R. (1991). A motivational approach to self: Integration in personality. In R. Dienstbier (Ed.), Nebraska symposium on motivation: Vol. 38. Perspectives on motivation (pp. 237–288). Lincoln: University of Nebraska Press.
- Deci, E. L., & Ryan, R. M. (1995). Human autonomy: The basis for true self-esteem. In M. Kernis (Ed.), Efficacy, agency, and self-esteem (pp. 3149). New York: Plenum.
- Deci, E., & Ryan, R. (Eds.), (2002). Handbook of self-determination research. Rochester, NY:University of Rochester Press.
- Deci, E., & Ryan, R. (2008). Facilitating optimal motivation and psychological well-being across life’s domains. Canadian Psychology, 49, 14–23.
- Fernet, C., Guay, F., & Senecal, C. (2004). Adjusting to job demands: The role of work self-determination and job control in predicting burnout. Journal of Vocational Behavior, 65, 39–56.
- Fortier, M. S., Sweet, S. N., O’Sullivan, T. L., & Williams, G. C. (2007). A self-determination process model of physical activity adoption in the context of a randomized controlled trial. Psychology of Sport and Exercise, 8, 741–757.
- Jang, Hyungshim . (2008). Supporting Students' Motivation, Engagement, and Learning During an Uninteresting Activity. Journal of Educational Psychology, 100(4), 798.
- Kennedy, S., Gogin, K., & Nollen, N. (2004). Adherence to HIV medications: Utility of the theory of self-determination. Cognitive Therapy and Research, 28, 611–628.
- Lepper, M. K., Greene, D., & Nisbett, R. (1973). Undermining children's intrinsic interest with extrinsic reward: A test of the "overjustification" hypothesis. Journal of Personality and Social Psychology, 28,129- 137.
- Lepper, M., & Greene, D. (1975). Turning play into work: Effects of adult surveillance and extrinsic rewards on children’s intrinsic motivation. Journal of Personality and Social Psychology, 31, 479-486
- Murcia, J., Roman, M., Galindo, C., Alonso, N., & Gonzalez-Cutre, D. (2008). Peers’ influence on exercise enjoyment: A self-determination theory approach. Journal of Sports Science and Medicine, 7, 23 - 31
- Moller, A., Deci, E., & Ryan, R. (2006). Choice and ego-depletion: The moderating role of autonomy. Personality and Social Psychology Bulletin, 32, 1024-1036.
- Pritchard, R., Campbell, K., & Campbell, D. (1977). Effects of extrinsic financial rewards on intrinsic motivation. Journal of Applied Psychology, 62, 9–15.
- Roth, G., Assor, A., Kanat-Maymon, Y., and Kaplan, H. (2007). Autonomous motivation for teaching: How self-determined teaching may lead to self-determined learning . Journal of Educational Psychology, 99, 761–774.
- Ryan, R. (1995). Psychological needs and the facilitation of integrative processes. Journal of Personality, 63, 397–427.
- Ryan, R., & Connell, J. (1989). Perceived locus of causality and internalization: Examining reasons for acting in two domains. Journal of Personality and Social Psychology, 57, 749–761.
- Ryan, R., & Deci, E. (2000). Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. American Psychologist, 55, 68-78.
- Ryan, R., & Deci, E. (2008). From ego-depletion to vitality: Theory and findings concerning the facilitation of energy available to the self. Social and Personality Psychology Compass, 2, 702–717.
- Soenens, B., Vansteenkiste, M., Lens, W., Luyckx, K., Beyers, W., Goossens, L., & Ryan, R. (2007). Conceptualizing parental autonomy support: Adolescent perceptions of promoting independence versus promoting volitional functioning. Developmental Psychology, 43, 633–646.
