Intrinsic Motivation Inventory (IMI)

1. Abstract

The Intrinsic Motivation Inventory (IMI) is a multidimensional, post-experimental measurement battery designed to assess participants’ subjective, phenomenological experiences regarding engagement in a specific target task or experimental manipulation. Grounded robustly within Cognitive Evaluation Theory (CET)—a mini-theory within the broader Self-Determination Theory (SDT) paradigm formulated by Edward L. Deci and Richard M. Ryan—the IMI operationalizes intrinsic motivation not merely as a unitary outcome, but as an ecologically sensitive construct intertwined with perceived autonomy, self-efficacy, psychophysiological tension, cognitive investment, utility valuation, and relational connectedness. While the complete conceptual reservoir of the instrument encompasses up to 45 items across seven structurally coherent subscales (Interest/Enjoyment, Perceived Competence, Perceived Choice, Pressure/Tension, Effort/Importance, Value/Usefulness, and Relatedness), standard validated laboratory iterations commonly deploy targeted modular subsets, such as the 22-item Task Evaluation Questionnaire, 25-item internalization variants, or customized 29-item interpersonal matrices.

Measurement utilizes a standardized 7-point Likert response format spanning from 1 (“not at all true”) to 7 (“very true”), with strategically placed reversed items designed to mitigate acquiescence response sets. Psychometrically, only the Interest/Enjoyment subscale serves as the direct operational self-report index of intrinsic motivation per se, whereas Perceived Competence and Perceived Choice act as theorized positive antecedent predictors, and Pressure/Tension functions as a definitive negative predictor. Confirmatory factor analytic investigations across diverse empirical domains, including educational psychology, sport science, human-computer interaction, and virtual simulations, consistently demonstrate robust structural stability, satisfactory incremental fit indices (CFI, TLI > .90; RMSEA < .06), strong internal consistency reliability (subscale Cronbach’s alphas frequently ranging between .80 and .92), and notable convergent validity with behavioral free-choice persistence paradigms.

2. Keywords

Intrinsic Motivation Inventory, Self-Determination Theory, Cognitive Evaluation Theory, Interest and Enjoyment, Perceived Competence, Perceived Choice, Pressure and Tension, Intrinsic Motivation Measurement, Task Internalization, Psychometrics

3. Authors

The Intrinsic Motivation Inventory was conceptualized, operationalized, and iteratively expanded primarily by prominent clinical and social personality psychologists at the University of Rochester:

• Richard M. Ryan, Ph.D. — Professor of Psychology and Education, University of Rochester; Research Professor, Institute for Positive Psychology and Education, Australian Catholic University. Co-founder of Self-Determination Theory. Contact: Institute for Positive Psychology and Education, Australian Catholic University, Strathfield, NSW, Australia. Email: [email protected].
• Edward L. Deci, Ph.D. (1942–2023) — Professor of Psychology and Gowen Professor in the Social Sciences, Department of Clinical and Social Sciences in Psychology, University of Rochester, Rochester, New York, USA.
• Key Early Psychometric Collaborators:
  • Edward McAuley, Ph.D. — Department of Kinesiology, University of Illinois at Urbana-Champaign, Champaign, Illinois, USA (pioneered the definitive Confirmatory Factor Analysis validation of the IMI in competitive sports settings in 1987).
  • Terry E. Duncan, Ph.D. and Vance V. Tammen, Ph.D. — Research methodologists who co-authored early structural equation modeling and construct validation evaluations.
  • Robert W. Plant, Ph.D., James P. Connell, Ph.D., and Richard Koestner, Ph.D. — Co-investigators in pioneering laboratory paradigms establishing the sensitivity of the IMI subscales to internal controlling styles, ego-involvement, and emotional dynamics during learning tasks.

4. Purpose

The core objective of the Intrinsic Motivation Inventory is to deliver a granular, multidimensional psychometric evaluation of an individual’s immediate subjective experience while performing a target activity. Historically, early motivation researchers relied extensively upon objective behavioral paradigms, predominantly the classic “free-choice” behavioral persistence protocol developed by Deci in 1971. In this design, participants are observed unobtrusively during an unprompted, free-time interval following an experimental manipulation to determine whether, and for how long, they spontaneously return to the target task in the absolute absence of external reinforcement, social demand, or surveillance. However, researchers quickly recognized that behavioral persistence alone can be contaminated by internal compulsions, compensatory ego-defensiveness, rigid perfectionism, or compliance. Consequently, the IMI was constructed as an essential post-experimental self-report battery designed to unpack the exact phenomenal nuances of human agency, task absorption, and emotional valence that accompany such behaviors.

In applied and laboratory environments, the IMI serves multiple crucial functions across educational, athletic, organizational, and technological domains:

• Experimental Manipulation Checks: In social psychology and cognitive sciences, researchers deploy the IMI immediately following experimental manipulations (such as the provision of controlling versus informational rewards, feedback delivery, competitive pressure, or autonomy-supportive instruction) to determine whether the manipulation successfully altered subjective feelings of autonomy, perceived competence, or tension.
• Deconstructing Internalization Dynamics: The instrument facilitates the empirical study of how individuals internalize uninteresting or non-intrinsically appealing activities. By integrating the Value/Usefulness subscale, investigators assess whether an activity, while perhaps lacking pure hedonic appeal, is integrated into an individual’s sense of self due to recognized utility and personal worth.
• Pedagogical and Human-Computer Interaction (HCI) Design Evaluation: Educators and digital game designers routinely leverage the scale to evaluate user engagement, experiential immersion, pedagogical software efficacy, and gamified interface mechanics. By isolating whether a digital intervention elevates interest or inadvertently introduces performance anxiety, developers can refine instructional tools to optimize intrinsic engagement without inducing debilitating performance pressure.
• Sport and Physical Activity Assessment: As evidenced by foundational research by McAuley and colleagues, the IMI functions reliably within athletic training regimens to identify competitive climates that preserve athlete self-determination versus environments that inadvertently trigger debilitating competitive anxiety and performance collapse.

A vital theoretical and practical feature of the IMI is its modular architecture. Unlike rigid clinical diagnostic tools that require absolute adherence to an invariant full-length manifest, the IMI allows researchers to select only those subscales that bear direct theoretical relevance to their explicit experimental hypotheses. For instance, if an investigation is solely centered on the impact of feedback on self-efficacy and anxiety, researchers may selectively administer the Perceived Competence and Pressure/Tension subscales alongside Interest/Enjoyment, omitting the Relatedness or Value/Usefulness subscales entirely without degrading the internal validity or psychometric reliability of the chosen dimensions.

5. Psychological Construct

The Intrinsic Motivation Inventory encompasses seven distinct psychological subscales, each capturing an idiosyncratic facet of human subjective experience. Rather than treating intrinsic motivation as an undifferentiated phenomenological block, the instrument treats interest/enjoyment as the direct experiential hallmark, while framing the remaining dimensions as its key psychological antecedents, correlates, or downstream experiential sequelae.

1. Interest/Enjoyment

The Interest/Enjoyment subscale represents the pure subjective self-report measure of intrinsic motivation per se. Within Self-Determination Theory, an individual is intrinsically motivated when they engage in an activity purely for its inherent satisfactions, excitement, aesthetic value, or curiosity, rather than for some separable consequence. Sample items assess cognitive absorption and affective delight, such as “I enjoyed doing this activity very much” and “I thought this activity was quite enjoyable.” Positively loading items directly contrast with reversed items gauging experiential boredom (e.g., “I thought this was a boring activity”). Because this subscale operationalizes the primary dependent variable of interest in classical intrinsic motivation research, it frequently features the greatest number of items within customized short forms.

2. Perceived Competence

Rooted conceptually in Robert White’s concept of effectance motivation and Albert Bandura’s work on self-efficacy, Perceived Competence captures an individual’s subjective sense of mastery, effectiveness, and execution capability during task engagement. Cognitive Evaluation Theory posits that activities which foster feelings of efficacy will enhance intrinsic motivation, provided that such competence is experienced within an internal locus of causality. Representative items include “I think I am pretty good at this activity” and “After working at this activity for awhile, I felt pretty competent.” In the absence of perceived competence, task participation tends to be characterized by learned helplessness or demotivation.

3. Perceived Choice

The Perceived Choice subscale directly operationalizes the core organismic need for autonomy and an internal perceived locus of causality (IPLOC). Individuals reporting high perceived choice experience themselves as the authentic origin of their actions, feeling psychological freedom and volition regarding their task participation. Conversely, an external perceived locus of causality (EPLOC) manifests as feeling coerced, controlled, or obligated. Typical items include “I believe I had some choice about doing this activity” and “I did this activity because I wanted to,” paired with heavily weighted reverse items such as “I did this activity because I had to” and “I felt like it was not my own choice to do this task.” Empirical findings consistently show that perceived choice is an indispensable prerequisite for maintaining intrinsic interest.

4. Pressure/Tension

The Pressure/Tension subscale assesses the psychophysiological distress, acute evaluation apprehension, and internally or externally experienced strain that an individual endures during an activity. Theoretically, this subscale is an explicit negative predictor of intrinsic motivation. Elevated tension indicates that an individual’s autonomy is compromised, often through external surveillance, rigid dead-lines, interpersonal competition, or internal ego-involvement (where self-esteem is contingent on performance). Illustrative items include “I felt very tense while doing this activity” and “I was anxious while working on this task,” complemented by reversed items tapping serenity (e.g., “I was very relaxed in doing these”).

5. Effort/Importance

The Effort/Importance subscale isolates the behavioral and cognitive energy, striving, and self-reported investment channeled toward performing an activity well. Unlike the core affective dimensions, effort can operate in service of either intrinsically motivated fascination or highly controlled introjected regulation (such as desperate striving driven by guilt or pride). Items include “I put a lot of effort into this” and “It was important to me to do well at this task.” When uncoupled from interest/enjoyment, elevated effort often mirrors pressured, compensatory persistence rather than spontaneous, playful engagement.

6. Value/Usefulness

Grounded in the Organismic Integration Theory branch of SDT, the Value/Usefulness subscale quantifies the degree to which an individual perceives an activity as personally beneficial, constructive, and instrumental for self-selected personal growth. This subscale is pivotal in internalization experiments, examining how individuals adopt uninteresting tasks (e.g., studying repetitive technical material, completing tedious workplace safety protocols) and become self-regulating through autonomous identification. Items are frequently customizable to the specific domain, such as “I believe this activity could be of some value to me” or “I think that doing this activity is useful for [improving concentration].”

7. Relatedness

The Relatedness subscale assesses interpersonal warmth, mutual trust, psychological safety, and the subjective sense of belonging experienced with experimenters, peers, or collaborative partners during a target task. Although intrinsic motivation can flourish in solitary intellectual pursuits, tasks executed within interpersonal matrices rely heavily upon a secure relational base. Items include “I felt like I could really trust this person,” “I feel close to this person,” and the reverse-scored “I felt really distant to this person.”

6. Theoretical Framework

The theoretical bedrock of the Intrinsic Motivation Inventory is firmly anchored within Self-Determination Theory (Deci & Ryan, 1985, 2000), and more specifically, its foundational mini-theory, Cognitive Evaluation Theory (CET). Formulated to explain the psychological mechanisms that mediate task interest, CET operates on the fundamental organismic-dialectical assumption that human beings possess an inherent, proactive developmental tendency toward exploring, mastering, and integrating experiences. This intrinsic orientation, however, is not automatic; it requires specific nutritional supports from the social environment and is exceedingly vulnerable to external control.

Cognitive Evaluation Theory asserts that external events, interpersonal climates, and intrapersonal dynamics impact intrinsic motivation via two essential psychological pathways:

• The Informational Aspect: Environmental factors (such as constructive feedback, praise, or choice architecture) that foster an internal perceived locus of causality and affirm effectance satisfy the basic psychological needs for autonomy and competence. In doing so, they nurture and enhance intrinsic motivation.
• The Controlling Aspect: Environmental factors (such as tangible contingent rewards, impending surveillance, restrictive dead-lines, or authoritarian directives) that shift an individual’s perceived locus of causality from internal to external induce psychological coercion. This controlling climate frustrates the need for autonomy, generates subjective pressure, and systematically undermines intrinsic interest—a phenomenon historically designated as the “overjustification effect.”

A vital theoretical nuance established by Ryan (1982) and Ryan, Koestner, and Deci (1991) involves the intrapersonal sphere: an individual can internalize controlling pressures. Under conditions of ego-involvement, an individual’s self-esteem and self-worth become rigidly contingent upon task performance. In such states, people pressure themselves to perform to avoid guilt or protect their pride. Although behavioral persistence during a subsequent free-choice period may appear outwardly elevated, this behavior represents “pressured persistence” driven by introjected tension rather than genuine autonomous interest. The multidimensional structure of the IMI was constructed precisely to dissect these intricate theoretical dynamics: by cross-examining high effort and persistence against elevated Pressure/Tension and depressed Interest/Enjoyment, the researcher can theoretically confirm whether engagement is truly intrinsically motivated or driven by internally controlling, ego-involved coercion.

Furthermore, Organismic Integration Theory (OIT) broadens this theoretical matrix by detailing the continuum of extrinsic motivation: from external regulation (behavior driven entirely by reward or punishment), through introjection (ego-protection and guilt avoidance), to identification (conscious valuing of an activity), and ultimately integration (full synthesis with core personal values). The IMI’s Value/Usefulness subscale explicitly tracks this critical transition into identified regulation, providing a validated empirical vehicle to measure whether individuals successfully internalize activities that may lack pure experiential playfulness yet remain essential for long-term health, education, and personal development.

7. Validity

The construct, convergent, discriminant, and predictive validity of the Intrinsic Motivation Inventory has been corroborated through decades of empirical testing across laboratory and applied field environments.

Construct and Factorial Validity

Early psychometric foundations were established by Ryan (1982), Ryan, Mims, and Koestner (1983), and Plant and Ryan (1985), demonstrating that the internal item structures within each designated subscale coalesce around their theoretical latent variables. Subscale items systematically exhibit factor loadings exceeding .60 on their target construct, while cross-loadings routinely fail to exceed the stringent cutoff of .40. In a definitive psychometric benchmark, McAuley, Duncan, and Tammen (1987) conducted the first rigorous Confirmatory Factor Analysis (CFA) of the IMI within a competitive collegiate sports setting ($N = 116$). Testing a four-factor model (Interest/Enjoyment, Competence, Effort, and Pressure/Tension), their structural equation models supported the multidimensionality of the scale, yielding robust fit parameters (Goodness-of-Fit Index $[GFI] = .802$ to $.91$ depending on item modifications) and demonstrating that the latent constructs were statistically discrete rather than collapsing into an undifferentiated general affective factor.

Convergent and Predictive Validity

Extensive laboratory research underscores the convergent validity of the IMI with behavioral indices. The Interest/Enjoyment subscale consistently correlates positively with the classic behavioral free-choice persistence paradigm—the number of seconds participants voluntarily spend playing with spatial puzzles (e.g., the Soma puzzle), educational games, or computer tasks during an unobserved, free-time interval (Deci et al., 1994; Ryan et al., 1991). As noted in early methodological papers, the magnitude of these correlations between self-reported interest and behavioral indices typically hovers in the moderate, realistic range of $r = .35$ to $.45$. This modest-to-moderate association is theoretically expected, because free-choice persistence is occasionally confounded by internal controlling styles (ego-involvement), reinforcing the conceptual imperative to measure both self-report and behavioral trajectories in parallel.

Discriminant and Experimental Validity

The discriminant validity of the instrument is evidenced by its capacity to disentangle subjective enjoyment from cognitive pressure and perceived choice across differentiated experimental paradigms:

• Controlling vs. Informational Feedback: Ryan (1982) demonstrated that experimentally induced ego-involvement drastically elevated scores on the Pressure/Tension subscale while attenuating free-choice persistence, whereas task-involved conditions elevated Interest/Enjoyment and Perceived Competence without inflating Pressure/Tension.
• Reward Contingency: Ryan, Mims, and Koestner (1983) applied the IMI to examine performance-contingent rewards administered in either a controlling or an informational interpersonal context. Results revealed divergent subscale trajectories: controlling rewards significantly suppressed Perceived Choice and Interest/Enjoyment, while informational rewards preserved perceived autonomy and significantly elevated Perceived Competence.
• Internalization Studies: Deci, Eghrari, Patrick, and Leone (1994) experimentally manipulated three facilitating factors for internalization during a monotonous task: providing a meaningful rationale, acknowledging negative feelings, and conveying choice. The Activity Perception Questionnaire (a 25-item version of the IMI) successfully discriminated between pure enjoyment and identified regulation: groups provided with rationales and choice displayed marked elevations on the Value/Usefulness subscale, predicting high subsequent free-choice persistence even when the Interest/Enjoyment scores remained low.

8. Reliability

The Intrinsic Motivation Inventory demonstrates exceptional internal consistency reliability across its individual subscales, corroborated across hundreds of empirical studies spanning laboratory psychology, educational interventions, medical education, and athletic performance.

Internal Consistency Reliability

In standard laboratory studies and structural validations, Cronbach’s alpha ($lpha$) coefficients for the respective subscales consistently surpass accepted psychometric benchmarks (typically exceeding .80):

• Interest/Enjoyment: Historically exhibits the highest internal reliability, with alpha coefficients routinely ranging between $\alpha = .85$ and $.92$ in both the full 7-item pool and abbreviated 4-to-5-item versions.
• Perceived Competence: Typically demonstrates internal consistency coefficients between $\alpha = .80$ and $.88$ (e.g., McAuley et al., 1987 reported $\alpha = .80$).
• Perceived Choice: Across diverse laboratory tasks, the internal consistency of Perceived Choice ranges from $\alpha = .82$ to $.89$.
• Pressure/Tension: Alpha values generally cluster between $\alpha = .78$ and $.86$, reflecting cohesive measurement of acute somatic and cognitive evaluation strain.
• Effort/Importance: Consistently yields Cronbach’s alphas ranging from $\alpha = .80$ to $.84$.
• Value/Usefulness: Demonstrated excellent internal consistency in internalization paradigms, with Deci et al. (1994) observing alphas exceeding $\alpha = .88$ for the composite utility items.
• Relatedness: In interpersonal laboratory and cooperative tasks, the Relatedness subscale typically manifests alphas between $\alpha = .85$ and $.91$.

Incremental Item Reliability and Redundancy

Psychometric evaluations conducted by the instrument’s developers revealed that individual items within a given subscale share substantial common variance. While this redundancy ensures structural coherence, empirical tests demonstrate that the incremental variance explained ($R^2$) for every item added beyond four items per latent factor is remarkably small. Consequently, investigators routinely utilize abbreviated 3-to-5-item subscale manifestations without incurring any appreciable drop in internal consistency reliability or predictive capability.

Test-Retest Stability Considerations

Because the IMI was purposefully engineered as a state-specific, post-experimental assessment designed to capture transient phenomenological reactions to an immediate task manipulation, traditional long-term test-retest reliability metrics are theoretically inappropriate. However, when tasks and environmental conditions remain identical across repeated laboratory blocks (e.g., baseline to control testing intervals separated by brief periods), short-term test-retest stability coefficients typically range from $r = .72$ to $.81$, indicating that while the scale is highly sensitive to external situational shifts, it remains stable in the absence of contextual interventions.

9. Factor Analysis

The structural dimensionality of the Intrinsic Motivation Inventory has been rigorously scrutinized via both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA).

Factor Loadings and Criteria for Item Inclusion

During the foundational development of the IMI item pool at the University of Rochester, strict empirical heuristics governed subscale construction. Items were retained only if they met two non-negotiable factor analytic criteria across repeated exploratory extractions:

• A primary factor loading of at least $lambda ge .60$ onto their designated theoretical latent factor.
• Cross-loadings on non-target factors strictly not exceeding $lambda le .40$.

In standard extractions, primary item loadings comfortably exceed .70, demonstrating clean, unconfounded factor saturation. Furthermore, extensive cross-experimental testing indicated that item order randomization exerts no significant carry-over or order effects on factor structure, and the inclusion or exclusion of individual subscales leaves the latent factor structure of remaining dimensions entirely intact.

Confirmatory Factor Analytic (CFA) Benchmarks

The landmark CFA validation by McAuley, Duncan, and Tammen (1987) evaluated the construct architecture of a 16-item version across four primary dimensions (Competence, Interest/Enjoyment, Effort, Pressure/Tension) in competitive athletics. Using maximum likelihood estimation, the researchers confirmed the four-factor oblique model over alternative rival unidimensional and orthogonal structures. While initial models displayed slight strain due to item phrase redundancies, modern structural equation re-examinations implementing contemporary fit metrics repeatedly demonstrate satisfactory structural alignment:

• Comparative Fit Index (CFI): Routinely ranges between $.91$ and $.96$.
• Tucker-Lewis Index (TLI): Frequently surpasses $.90$.
• Root Mean Square Error of Approximation (RMSEA): Consistently maintains values between $.045$ and $.065$, with $90%$ confidence intervals firmly below the conventional $.08$ cutoff.
• Standardized Root Mean Square Residual (SRMR): Typically falls below $.05$.

These findings substantiate that the IMI does not constitute a singular global intrinsic motivation metric, but rather a differentiated constellation of psychologically distinct constructs that relate to one another in theoretical patterns predicted by Cognitive Evaluation Theory.

10. Instrument / Measurement Tool

• Test Type: Multidimensional, state-specific psychological self-report inventory / post-experimental survey instrument.
• Administration Format: Paper-and-pencil questionnaire, automated digital survey, or embedded online research task. Typically self-administered immediately following task completion.
• Completion Time: Approximately 3 to 7 minutes, depending on the modular subset and item count selected.
• Item Count:
  • Full theoretical item bank: 45 items across 7 subscales.
  • Standard laboratory Task Evaluation Questionnaire: 22 items across 4 subscales.
  • Internalization Activity Perception Questionnaire: 25 items across 3 subscales.
  • Interpersonal Relatedness matrix: 29 items across 5 subscales.
  • Ultra-short reading text version: 9 items across 3 subscales.
• Target Population: Adolescents, university undergraduate samples, and adult populations across laboratory experiments, educational settings, competitive sports, and digital workplace evaluations.
• Response Scale: 7-point Likert response format with explicit semantic anchor points:
  • 1 = Not at all true
  • 2 = (unlabeled intermediate)
  • 3 = (unlabeled intermediate)
  • 4 = Somewhat true
  • 5 = (unlabeled intermediate)
  • 6 = (unlabeled intermediate)
  • 7 = Very true
• Scoring Rules and Algorithms:
  • Reversed Scoring: All reverse-valenced items (designated with an (R)) must be reversed prior to computing composite scores. On the 7-point metric, reversed scores are transformed using the algebraic formula: $$\text{Item}_{\text{reversed}} = 8 – \text{Item}_{\text{raw}}$$
  • Subscale Computation: A subscale score is generated by calculating the arithmetic mean (average) of the individual items assigned to that subscale. Utilizing subscale averages (ranging from 1.0 to 7.0) rather than raw sum scores is strongly recommended, as it retains the intuitive 7-point Likert frame and accommodates variations in item counts across study designs.
  • No Overall Global Score: There is no valid “total IMI score.” The instrument is deliberately designed as a modular profile; summing across all dimensions erroneously combines positive predictors (competence, choice) with negative predictors (pressure/tension) and distinct outcomes (effort, value). Researchers must report and analyze subscales as separate continuous variables.
  • Task Adaptation: Researchers are actively encouraged to tailor the activity referent within item stems to the target task (e.g., replacing “this activity” with “these puzzles,” “this simulation,” or “this text material”) without altering psychometric properties.

11. Permissions & Fee and Test Year

• Initial Publication and Development Period: 1982–1994 (Pioneered by Richard M. Ryan in 1982; formalized with factor analytic validations by McAuley, Duncan, & Tammen in 1987; expanded for internalization paradigms by Deci, Eghrari, Patrick, & Leone in 1994).
• Copyright and Licensing: The Intrinsic Motivation Inventory is an open-access, public domain research instrument developed under academic research initiatives funded in part by the National Institute of Mental Health (NIMH) and the University of Rochester.
• Permissions: Free for use in academic, non-commercial research, theses, dissertations, and institutional investigations. No formal written permission or royalty payment is required from the original authors or the Center for Self-Determination Theory.
• Commercial and Clinical Use: Commercial entities utilizing the scale in commercial applications, corporate human resource assessments, or proprietary software platforms are expected to cite the original authors appropriately and ensure that the integrity of the theoretical framework is maintained.
• Official Repository: Standardized versions, scoring protocols, and conceptual documentation are hosted publicly by the Center for Self-Determination Theory at selfdeterminationtheory.org.

12. References

Deci, E. L. (1971). Effects of externally mediated rewards on intrinsic motivation. Journal of Personality and Social Psychology, 18(1), 105–115. https://doi.org/10.1037/h0030644

Deci, E. L., Eghrari, H., Patrick, B. C., & Leone, D. R. (1994). Facilitating internalization: The self-determination theory perspective. Journal of Personality, 62(1), 119–142. https://doi.org/10.1111/j.1467-6494.1994.tb00797.x

Deci, E. L., & Ryan, R. M. (1985). Intrinsic motivation and self-determination in human behavior. Plenum Press. https://doi.org/10.1007/978-1-4899-2271-7

Deci, E. L., & Ryan, R. M. (2000). The “what” and “why” of goal pursuits: Human needs and the self-determination of behavior. Psychological Inquiry, 11(4), 227–268. https://doi.org/10.1207/S15327965PLI1104_01

McAuley, E., Duncan, T., & Tammen, V. V. (1987). Psychometric properties of the Intrinsic Motivation Inventory in a competitive sport setting: A confirmatory factor analysis. Research Quarterly for Exercise and Sport, 60(1), 48–58. https://doi.org/10.1080/02701367.1989.10607413

Plant, R. W., & Ryan, R. M. (1985). Intrinsic motivation and the effects of self-consciousness, self-awareness, and ego-involvement: An investigation of internally-controlling styles. Journal of Personality, 53(3), 435–449. https://doi.org/10.1111/j.1467-6494.1985.tb00375.x

Ryan, R. M. (1982). Control and information in the intrapersonal sphere: An extension of cognitive evaluation theory. Journal of Personality and Social Psychology, 43(3), 450–461. https://doi.org/10.1037/0022-3514.43.3.450

Ryan, R. M., Connell, J. P., & Plant, R. W. (1990). Emotions in non-directed text learning. Learning and Individual Differences, 2(1), 1–17. https://doi.org/10.1016/1041-6080(90)90014-8

Ryan, R. M., & Deci, E. L. (2017). Self-determination theory: Basic psychological needs in motivation, development, and wellness. Guilford Press. https://doi.org/10.1521/978.14625/28806

Ryan, R. M., Koestner, R., & Deci, E. L. (1991). Varied forms of persistence: When free-choice behavior is not intrinsically motivated. Motivation and Emotion, 15(3), 185–205. https://doi.org/10.1007/BF00995170

Ryan, R. M., Mims, V., & Koestner, R. (1983). Relation of reward contingency and interpersonal context to intrinsic motivation: A review and test using cognitive evaluation theory. Journal of Personality and Social Psychology, 45(4), 736–750. https://doi.org/10.1037/0022-3514.45.4.736

13. Items of the Scale