Curiosity and Exploration Inventory (CEI-II)

1. Abstract

The Curiosity and Exploration Inventory-II (CEI-II) is a 10-item self-report psychological instrument developed by Todd B. Kashdan and colleagues to assess individual differences in trait curiosity and the behavioral propensity to seek out, explore, and integrate novel and challenging experiences. Building upon limitations identified in the original Curiosity and Exploration Inventory (CEI; Kashdan et al., 2004), the CEI-II resolves prior psychometric concerns regarding factor instability and narrow construct representation by modeling curiosity as a two-dimensional, appetitive self-regulatory system. The instrument comprises two correlated yet distinct subscales: Stretching (five items), which measures the appetitive drive to seek out new knowledge, skills, and experiences, and Embracing (five items), which reflects a willingness to tolerate, welcome, and engage with the inherently uncertain, complex, and unpredictable nature of everyday life.

Respondents complete the CEI-II using a 5-point Likert-type scale ranging from 1 (very slightly or not at all) to 5 (extremely). Across extensive psychometric investigations, the inventory has demonstrated robust internal consistency reliability (Cronbach’s alpha coefficients typically ranging from .83 to .86 for the full scale and .74 to .83 for the subscales), stable test-retest reliability across multi-week intervals, and solid structural validity confirmed via exploratory structural equation modeling and confirmatory factor analysis. The CEI-II exhibits high convergent validity with openness to experience, intrinsic motivation, subjective vitality, psychological well-being, and reward sensitivity, as well as distinct discriminant and incremental validity over generalized positive affect, extraversion, and neuroticism in predicting behavioral, social, and emotional outcomes. Requiring less than two minutes to administer, the CEI-II provides researchers and clinicians with an efficient, psychometrically sound metric for personality, educational, organizational, and positive clinical psychology contexts.

2. Keywords

Curiosity and Exploration Inventory-II, CEI-II, curiosity, epistemic curiosity, exploratory behavior, stretching, embracing, positive psychology, open-mindedness, psychometrics, uncertainty tolerance, intrinsic motivation, trait assessment

3. Authors

The Curiosity and Exploration Inventory-II was conceptualized, developed, and validated through a collaborative psychometric research program led by academic psychologists specializing in personality, emotion regulation, and positive clinical science:

• Todd B. Kashdan, Ph.D. — Professor of Psychology and Director of the Well-Being Laboratory at George Mason University, Fairfax, Virginia, United States. Contact: [email protected].
• Matthew W. Gallagher, Ph.D. — Associate Professor of Clinical Psychology and Research Investigator at the Texas Center for Disabilities and the Department of Psychology, University of Houston, Houston, Texas, United States.
• Paul J. Silvia, Ph.D. — Professor of Psychology at the University of North Carolina at Greensboro, Greensboro, North Carolina, United States.
• Brian P. Winterstein, Ph.D. — Assessment Specialist and Research Scientist in clinical psychology and behavioral measurement.
• William E. Breen, Ph.D. — Clinical Psychologist specializing in anxiety disorders and emotional resilience.
• Danielle Terhar, M.A. — Clinical researcher focused on positive psychological intervention and well-being.
• Michael F. Steger, Ph.D. — Professor of Psychology and Director of the Center for Meaning and Purpose at Colorado State University, Fort Collins, Colorado, United States.

4. Purpose

The primary purpose of the Curiosity and Exploration Inventory-II (CEI-II) is to quantify individual differences in the recognition, pursuit, and active cognitive and behavioral integration of novel, complex, and uncertain events. In psychological science, curiosity has historically been conceptualized under various frameworks, ranging from Berlyne’s arousal-reduction models to modern appetitive reward mechanisms. The original CEI (Kashdan et al., 2004) represented a major effort to introduce a standardized trait metric capturing both exploration and absorption. However, subsequent independent empirical investigations noted psychometric limitations with the initial scale, including inconsistent structural replications, modest factor loading patterns in non-student populations, and the fact that the original absorption subscale frequently correlated poorly with broad exploratory tendencies or showed conceptual overlap with pure attentional flow.

To overcome these theoretical and statistical shortcomings, Kashdan, Gallagher, Silvia, and colleagues (2009) redesigned the instrument to reflect contemporary affective-cognitive theories of curiosity. Rather than viewing curiosity merely as passive fascination or momentary attentional absorption, the CEI-II models curiosity as an active, self-regulatory motive composed of two complementary behavioral processes: intentional information-gathering (“stretching”) and comfort with experiential ambiguity (“embracing”).

In applied and research settings, the CEI-II fulfills several essential functions:

• Basic Personality and Affective Science: It serves as a benchmark metric for investigating how curiosity acts as an appetitive motivational engine driving personal growth, cognitive development, meaning in life, and creative problem-solving.
• Clinical and Counseling Psychology: The inventory provides diagnostic utility for assessing exploratory deficits, experiential avoidance, and behavioral inhibition commonly observed in major depressive disorder, generalized anxiety disorder, and social anxiety disorder. In clinical contexts, elevations in CEI-II scores often reflect increasing psychological flexibility and resilience during cognitive behavioral and acceptance-based interventions.
• Educational Psychology and Lifelong Learning: The scale enables educational researchers to examine intrinsic academic engagement, metacognition, and autonomous motivation, demonstrating how curiosity facilitates academic self-efficacy and superior conceptual retention beyond baseline cognitive intelligence.
• Organizational Behavior and Leadership: Human resource professionals and organizational psychologists utilize the CEI-II to assess intellectual agility, adaptability to workplace change, innovation capability, and openness to unfamiliar professional responsibilities.

5. Psychological Construct

The CEI-II conceptualizes curiosity as a positive, appetitive state that initiates, guides, and maintains exploratory engagement with the external environment and inner experience. Unlike deficit-reduction models of curiosity—which view information seeking primarily as an uncomfortable tension state akin to hunger that must be eliminated—the construct underlying the CEI-II views curiosity as intrinsically rewarding approach-oriented motivation. This construct is partitioned into two distinct, highly synchronized dimensions:

Stretching (Exploratory Drive)

Stretching refers to the deliberate motivation to seek out novel, complex, and intellectually or experientially challenging information, knowledge, and situations to expand one’s mental horizons, competencies, and self-concept. Individuals with high stretching tendencies do not merely consume familiar stimuli; they actively venture beyond routine behavioral repertoires to acquire unfamiliar knowledge and master demanding skills. Stretching involves an appetitive impulse to push personal boundaries.

Behavioral Examples of Stretching:

• A university student intentionally choosing advanced, cross-disciplinary seminars outside their comfort zone rather than familiar introductory courses.
• A software engineer studying novel, paradigm-shifting programming languages simply for the pleasure of conceptual expansion and intellectual mastery.
• An individual approaching a socially unfamiliar gathering by asking probing questions to understand others’ worldviews.

Embracing (Willingness to Engage Uncertainty)

Embracing captures the affective and cognitive orientation toward tolerating, welcoming, and finding enjoyment in the inherent unpredictability, ambiguity, and unfamiliarity of everyday existence. While stretching focuses on the purposeful pursuit of novelty, embracing concerns the person’s stance toward the spontaneous, uncontrolled, and messy nature of experience. Individuals with low embracing tendencies experience distress, anxiety, and rigid avoidance when confronted with ambiguous circumstances. Conversely, individuals scoring high on embracing interpret unpredictability as an exciting opportunity for discovery rather than a psychological threat.

Behavioral Examples of Embracing:

• A traveler navigating a foreign city without an itinerary, viewing getting lost as an exciting adventure rather than a source of panic.
• An employee thriving in an agile, rapidly pivoting organizational environment characterized by shifting priorities and unscripted challenges.
• A person willingly trying exotic foods or participating in activities that evoke mild apprehension, recognizing that mild fear frequently accompanies meaningful growth.

6. Theoretical Framework

The Curiosity and Exploration Inventory-II is theoretically grounded in the convergence of modern affective neuroscience, developmental theory, and positive psychology. Four primary theoretical frameworks underpin the scale’s design:

1. Berlyne’s Collative-Arousal and Epistemic Theory

Daniel Berlyne’s seminal work on exploratory behavior distinguished between diversive exploration (seeking stimulation to alleviate boredom) and epistemic exploration (seeking specific knowledge to resolve conceptual gaps). Berlyne identified “collative variables”—novelty, complexity, uncertainty, and conflict—as the structural triggers that induce curiosity. The CEI-II adopts Berlyne’s collative variables as core experiential stimuli while integrating modern insights indicating that the pursuit of these conditions can be pleasurable and rewarding in its own right, rather than solely a drive-reduction process.

2. The Broaden-and-Build Theory of Positive Emotions

Formulated by Barbara Fredrickson, the Broaden-and-Build Theory posits that while negative emotions narrow momentary thought-action repertoires to promote immediate physical survival, positive emotions broaden an individual’s cognitive and behavioral repertoires, leading to the building of enduring psychological, social, and intellectual resources. In Fredrickson’s taxonomy, curiosity (or interest) stands alongside joy, pride, and love as a quintessential broadening emotion. When individuals experience curious engagement, their attention broadens, cognitive flexibility increases, and they acquire novel knowledge schemas, social networks, and coping skills that become permanent cognitive and emotional reserves.

3. Self-Determination Theory (SDT)

Edward Deci and Richard Ryan’s Self-Determination Theory highlights the central role of intrinsic motivation—the inherent tendency to seek out novelty and challenges, to extend and exercise one’s capacities, and to learn. The CEI-II explicitly aligns with SDT by framing curiosity as an autonomous, intrinsically regulated process. High scorers on stretching and embracing are motivated by the inherent experiential value of exploration rather than external contingencies, social validation, or instrumental reward.

4. Appraisal Theory of Emotion

Paul Silvia’s appraisal model of interest specifies that the subjective emotion of curiosity arises from two distinct, consecutive cognitive appraisals: (a) novelty-complexity appraisal (evaluating whether a stimulus is new, ambiguous, unexpected, or intricate) and (b) comprehensibility appraisal (evaluating whether one has the coping resources, ability, or capacity to understand, manage, and integrate the experience). The CEI-II reflects this dual-appraisal system: Stretching represents the active orientation toward high-novelty and high-complexity environments, whereas Embracing reflects high perceived coping efficacy and positive valuation when facing unpredictable, unfamiliar, and ambiguous contexts.

7. Validity

The construct, convergent, discriminant, and predictive validity of the CEI-II have been established across numerous empirical investigations comprising undergraduate samples, clinical populations, community cohorts, and multinational settings.

Construct and Structural Validity

In the foundational validation paper by Kashdan, Gallagher, Silvia, et al. (2009), structural equation modeling demonstrated that a two-factor correlated model (Stretching and Embracing) provided superior fit over single-factor, orthogonal, and hierarchical models. Across multiple independent samples (totaling over 1,500 participants), the two-factor solution demonstrated invariant structural configurations across gender, age groups, and academic backgrounds.

Convergent Validity

The CEI-II exhibits statistically significant, theory-consistent correlations with broad personality traits and affective states:

• Openness to Experience: Demonstrates strong positive associations ($r = .50$ to $.65$, $p < .001$) with the Openness to Experience domain of the Big Five Personality Traits (NEO-PI-R and BFI), confirming its position within the broader intellectual and experiential exploration space.
• Subjective Vitality and Positive Affect: Strongly correlates with subjective vitality ($r = .45$ to $.55$) and trait positive affect ($r = .35$ to $.48$) on the Positive and Negative Affect Schedule (PANAS).
• Intrinsic Motivation and Need for Cognition: Correlates positively with intrinsic motivation toward learning ($r = .42$) and Cacioppo’s Need for Cognition Scale ($r = .46$).
• Behavioral Activation System (BAS): Exhibits moderate-to-strong correlations with the BAS Drive and BAS Fun Seeking subscales of the Carver and White BIS/BAS scales ($r = .34$ to $.44$), supporting its nature as an appetitive motivational construct.

Discriminant and Incremental Validity

Crucially, the CEI-II shows discriminant validity from constructs with which it might superficially overlap:

• Low-to-Negligible Correlation with Negative Affect: Shows minimal or non-significant correlations with the PANAS Negative Affect subscale ($r = -.10$ to $.04$) and neuroticism ($r = -.12$).
• Separation from Sensation Seeking: While the Embracing subscale shares modest variance with sensation seeking ($r \approx .30$), the CEI-II does not correlate with impulsivity or antisocial risk-taking. Curiosity-driven risk in the CEI-II is oriented toward growth, intellectual discovery, and experiential learning, whereas classical sensation seeking focuses on physical thrill and disinhibition.
• Incremental Predictive Power: Hierarchical multiple regressions have demonstrated that the CEI-II accounts for unique, incremental variance in psychological well-being, life satisfaction, daily social closeness, and creative problem-solving performance even after statistically controlling for the Big Five personality traits, generalized positive affect, and self-esteem (Kashdan et al., 2009, 2011).

8. Reliability

The CEI-II has exhibited high internal consistency, temporal stability, and measurement precision across laboratory and field settings:

Internal Consistency Reliability

Across diverse academic and community samples, internal consistency coefficients for the CEI-II exceed accepted psychometric benchmarks:

• Total Score: Cronbach’s alpha ($lpha$) coefficients consistently range between .83 and .86. McDonald’s omega ($\omega_t$) similarly exceeds .85, confirming reliable composite variance.
• Stretching Subscale: Cronbach’s $lpha$ ranges from .76 to .82 across validation cohorts.
• Embracing Subscale: Cronbach’s $lpha$ ranges from .74 to .80 across validation cohorts.
• Inter-Item Correlations: Mean inter-item correlations fall within the recommended optimal range of .30 to .50, demonstrating adequate item coherence without redundancy.

Test-Retest Stability

Temporal stability assessments reveal that individual differences in CEI-II trait curiosity remain stable over time:

• Over a two-week interval, test-retest reliability was observed at $r = .80$ for the total score, $r = .78$ for Stretching, and $r = .75$ for Embracing.
• Over a six-week interval, stability coefficients remained substantial, ranging from $r = .70$ to $r = .76$, supporting the conceptualization of the CEI-II as an enduring personality trait.
• State-based diary adaptations of the CEI-II have demonstrated daily intra-individual variability sensitive to environmental enrichment and social interactions while retaining stable baseline individual set-points.

9. Factor Analysis

The factorial composition of the CEI-II was established through systematic psychometric procedures involving exploratory factor analysis (EFA), parallel analysis, and confirmatory factor analysis (CFA) across independent samples during its initial development (Kashdan et al., 2009).

Confirmatory Factor Analysis (CFA) Fit Indices

CFA conducted on cross-validation cohorts demonstrated excellent fit indices for the hypothesized correlated two-factor model, satisfying strict Hu and Bentler (1999) structural criteria:

• Comparative Fit Index (CFI): $ge .96$
• Tucker-Lewis Index (TLI): $ge .95$
• Root Mean Square Error of Approximation (RMSEA): $.048$ to $.055$ (90% Confidence Interval: $[.036, .068]$)
• Standardized Root Mean Square Residual (SRMR): $.038$ to $.044$
• Chi-Square to Degrees of Freedom Ratio ($\chi^2/df$): $< 2.2$

Alternative model comparisons indicated that a unidimensional (single-factor) model exhibited markedly degraded fit ($ ext{CFI} < .88$,$ ext{RMSEA} > .095$), underscoring the psychometric necessity of distinguishing between the appetitive seeking of new knowledge (Stretching) and the receptive willingness to experience uncertainty (Embracing).

Factor Loadings and Inter-Factor Association

All 10 standardized item factor loadings in CFA solutions are robust and statistically significant ($p < .001$):

• Stretching Factor Loadings: Standardized factor loadings range from .62 to .79 onto their designated dimension.
• Embracing Factor Loadings: Standardized factor loadings range from .58 to .76 onto their designated dimension.
• Factor Correlation: The latent correlation between the Stretching and Embracing dimensions ranges between $r = .55$ and $r = .65$. This moderate-to-high shared variance confirms that while both factors reflect overarching exploratory strivings, they represent distinct behavioral and cognitive facets.

10. Instrument / Measurement Tool

• Instrument Name: Curiosity and Exploration Inventory-II (CEI-II)
• Instrument Type: Self-report trait psychometric questionnaire
• Target Population: Adults and adolescents (ages 14 and older)
• Administration Format: Paper-and-pencil, computer-administered, or mobile survey delivery
• Completion Time: Less than 2 minutes (no formal time limit)
• Item Count: 10 items
• Dimensional Structure: Two subscales:
  • Stretching Subscale: Items 1, 3, 5, 7, 9 (assesses active information seeking and personal growth pursuit)
  • Embracing Subscale: Items 2, 4, 6, 8, 10 (assesses comfort with, and enjoyment of, uncertainty, novelty, and unpredictability)
• Authentic Response Scale: 5-point Likert scale:
  • 1 = Very slightly or not at all
  • 2 = A little
  • 3 = Moderately
  • 4 = Quite a bit
  • 5 = Extremely
• Scoring Procedures:
  • Reverse-Scoring: None. All items are positively keyed.
  • Subscale Scores: Sum or average the corresponding items for each subscale (Stretching: sum range = 5–25, mean range = 1.0–5.0; Embracing: sum range = 5–25, mean range = 1.0–5.0).
  • Total Score: Sum or average all 10 items (sum range = 10–50, mean range = 1.0–5.0). Higher scores denote elevated trait curiosity and exploration.

11. Permissions & Fee and Test Year

The Curiosity and Exploration Inventory-II was formally published in 2009 by Todd B. Kashdan, Matthew W. Gallagher, Paul J. Silvia, Brian P. Winterstein, William E. Breen, Danielle Terhar, and Michael F. Steger in the Journal of Research in Personality.

Licensing and Accessibility: The CEI-II is an open-access, non-commercial assessment instrument released for academic, research, and non-profit educational purposes. The authors permit the use, reproduction, and translation of the inventory without royalty fees, provided proper bibliographic attribution is cited in resulting publications. Commercial utilization, automated integration into proprietary commercial diagnostic suites, or distribution within revenue-generating software requires explicit written permission from the copyright holders and the primary author, Dr. Todd B. Kashdan.

12. References

Berlyne, D. E. (1960). Conflict, arousal, and curiosity. McGraw-Hill. https://doi.org/10.1037/11164-000

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

Fredrickson, B. L. (2001). The role of positive emotions in positive psychology: The broaden-and-build theory of positive emotions. American Psychologist, 56(3), 218–226. https://doi.org/10.1037/0003-066X.56.3.218

Hu, L., & Bentler, P. M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling: A Multidisciplinary Journal, 6(1), 1–55. https://doi.org/10.1080/10705519909540118

Kashdan, T. B., Dewall, C. N., Pond, R. S., Silvia, P. J., Lambert, N. M., Fincham, F. D., Savostyanova, A. A., & Keller, P. S. (2013). Curiosity protects against interpersonal aggression: Cross-sectional, daily process, and behavioral evidence. Journal of Personality, 81(1), 87–102. https://doi.org/10.1111/j.1467-6494.2012.00783.x

Kashdan, T. B., Gallagher, M. W., Silvia, P. J., Winterstein, B. P., Breen, W. E., Terhar, D., & Steger, M. F. (2009). The Curiosity and Exploration Inventory-II: Development, factor structure, and psychometrics. Journal of Research in Personality, 43(6), 987–998. https://doi.org/10.1016/j.jrp.2009.04.011

Kashdan, T. B., McKnight, P. E., Fincham, F. D., & Rose, P. (2011). When curiosity breeds intimacy: Taking advantage of intimacy opportunities and transforming boring conversations. Journal of Personality, 79(6), 1369–1401. https://doi.org/10.1111/j.1467-6494.2010.00697.x

Kashdan, T. B., Rose, P., & Fincham, F. D. (2004). Curiosity and exploration: Facilitating positive subjective experiences and personal growth opportunities. Journal of Personality Assessment, 82(3), 291–305. https://doi.org/10.1207/s15327752jpa8203_05

Silvia, P. J. (2006). Exploring the psychology of interest. Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195158557.001.0001

13. Items of the Scale