Acceptance and Action Questionnaire – II (AAQ-II)

Abstract

The Acceptance and Action Questionnaire – II (AAQ-II) is currently the most widely utilized psychometric instrument designed to assess experiential avoidance and psychological inflexibility, which constitute the central transdiagnostic vulnerability constructs within the Acceptance and Commitment Therapy (ACT) model and modern functional contextual behavioral science. Developed by Bond and colleagues (2011) to overcome the structural, psychometric, and internal consistency limitations of the original 9-item and 16-item versions of the Acceptance and Action Questionnaire (AAQ-1; Hayes et al., 2004), the AAQ-II is an efficient, 7-item self-report questionnaire scored on a 7-point Likert scale ranging from 1 (Never true) to 7 (Always true). The scale yields a single unidimensional composite score ranging from 7 to 49, where higher numerical totals indicate greater psychological inflexibility, excessive cognitive fusion, and maladaptive experiential avoidance.

Extensive psychometric investigations across diverse clinical, non-clinical, collegiate, and multinational cohorts establish strong internal consistency, with mean Cronbach’s alpha ($lpha$) coefficients averaging .88 across developmental samples and .87 in psychiatric outpatient samples. Longitudinal test-retest reliability estimates demonstrate satisfactory temporal stability over 3-month ($r = .81$) and 12-month ($r = .79$) intervals. Exploratory and confirmatory factor analyses overwhelmingly endorse a single latent factor structure with uniformly high standardized item loadings ($lambda = .64 – .85$). The instrument exhibits strong convergent validity with measures of depressive symptomatology, generalized anxiety, somatization, thought suppression, and general psychological distress, alongside anticipated negative correlations with subjective well-being, mindfulness facets, and life satisfaction. Despite its clinical ubiquity, the instrument has spurred vigorous psychometric debates regarding whether it captures a distinct transdiagnostic behavioral process or represents a generalized negative affectivity/neuroticism proxy. This article delivers a rigorous academic dissection of the instrument’s background, theoretical foundations, psychometric architecture, diagnostic utility, and clinical interpretation.

Keywords

Acceptance and Action Questionnaire-II, psychological inflexibility, experiential avoidance, Acceptance and Commitment Therapy, Relational Frame Theory, psychometrics, transdiagnostic assessment, cognitive fusion, factor analysis, construct validity

Authors

The Acceptance and Action Questionnaire – II was developed and validated by an international consortium of prominent clinical psychologists and quantitative methodologists led by Frank W. Bond (Goldsmiths, University of London, United Kingdom). The developmental cohort of investigators includes:

• Frank W. Bond, Ph.D. — Professor of Psychology, Department of Psychology, Goldsmiths, University of London, London, United Kingdom. Primary investigator specializing in occupational health psychology, workplace psychological flexibility, and contextual behavioral science.
• Steven C. Hayes, Ph.D. — Nevada Foundation Professor Emeritus of Psychology, Department of Psychology, University of Nevada, Reno, USA. Originator of Acceptance and Commitment Therapy and co-developer of Relational Frame Theory.
• Ruth A. Baer, Ph.D. — Professor of Psychology, Department of Psychology, University of Kentucky, Lexington, Kentucky, USA. Internationally recognized authority on mindfulness assessment and dialectical behavioral strategies.
• Kelly M. Carpenter, Ph.D. — Research Scientist, Department of Psychiatry, Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, New York, USA.
• Nigel Guenole, Ph.D. — Quantitative psychometrician and Senior Lecturer, Goldsmiths, University of London, London, United Kingdom.
• Holly K. Orcutt, Ph.D. — Professor of Psychology, Department of Psychology, Northern Illinois University, DeKalb, Illinois, USA. Specializing in trauma, posttraumatic stress disorder, and experiential avoidance.
• Jennifer Waltz, Ph.D. — Professor of Psychology, Department of Psychology, University of Montana, Missoula, Montana, USA. Expert in dialectical behavior therapy, ACT, and third-wave behavioral interventions.
• Robert D. Zettle, Ph.D. — Professor Emeritus of Psychology, Department of Psychology, Wichita State University, Wichita, Kansas, USA. Author of foundational ACT texts and early clinical trials on contextual treatments for depression.

Correspondence concerning the primary psychometric validation of the AAQ-II was historically directed to Frank W. Bond at the Department of Psychology, Goldsmiths, University of London, New Cross, London SE14 6NW, United Kingdom (Email: [email protected]).

Purpose

The Acceptance and Action Questionnaire – II was created to fulfill a vital clinical and scientific mandate: providing a reliable, psychometrically robust, and brief measurement instrument capable of quantifying the functional target of Acceptance and Commitment Therapy: psychological inflexibility and its operative component, experiential avoidance. The precursor instrument, the original Acceptance and Action Questionnaire (AAQ-1; Hayes et al., 2004), was released in both 9-item and 16-item variants. While groundbreaking, the AAQ-1 suffered from persistent psychometric liabilities, including marginal internal consistency (Cronbach’s $lpha$ frequently hovering between .70 and .72 in non-clinical cohorts and dipping below .65 in several cross-validation field trials), a volatile and unstable multi-factor solution across independent translations, and ambiguous item phrasing that required extensive reverse-scoring adjustments.

To overcome these limitations, Bond and colleagues undertook a multi-year, multi-center psychometric revision. The clinical and empirical purpose of the resulting AAQ-II spans several key domains:

• Process-Based Outcome Assessment: Unlike conventional diagnostic inventories—such as the Beck Depression Inventory (BDI-II) or the Patient Health Questionnaire-9 (PHQ-9)—which quantify the manifest frequency and intensity of clinical symptoms, the AAQ-II assesses how individuals relate functionally to their unwanted internal experiences (thoughts, somatic sensations, emotional surges, and historical memories). It determines whether individuals allow these experiences to dictate their behavior or whether they can engage in meaningful, values-congruent living in their presence.
• Monitoring Treatment Mediators: In contemporary randomized controlled trials (RCTs) and single-case experimental designs, the AAQ-II serves as the quintessential process mediator. It allows researchers to confirm whether therapeutic gains in functional outcomes (e.g., pain reduction, occupational re-engagement, lowered medical utilization) are statistically mediated by shifts in psychological flexibility, rather than mere symptom extinction.
• Clinical Case Conceptualization and Functional Analysis: In outpatient clinical practice, baseline AAQ-II scores provide clinicians with an objective metric of rigid behavioral repertoires. High scores alert the therapist to clients who engage in pervasive behavioral constriction, excessive cognitive fusion, and maladaptive avoidance strategies (such as substance use, social withdrawal, or compulsive worry) designed to suppress emotional pain.
• Cross-Diagnostic Screening in Organizational and Medical Settings: Beyond psychiatric clinics, the AAQ-II is routinely administered in organizational psychology to predict employee burnout, absenteeism, work engagement, and subjective performance under cognitive load. Similarly, in behavioral medicine, the instrument gauges how patients cope with chronic somatic conditions, including chronic back pain, fibromyalgia, oncology-related distress, and type 2 diabetes management.

Psychological Construct

The primary psychological constructs measured by the AAQ-II are psychological inflexibility and its core component, experiential avoidance. Within contemporary contextual behavioral science, these constructs are conceptualized not as static personality traits or categorical mental illness states, but rather as persistent, generalized patterns of verbal behavioral regulation.

Experiential Avoidance

Experiential avoidance is defined as the phenomenon that occurs when an individual is unwilling to remain in contact with particular private experiences (including affective states, bodily sensations, cognitive thoughts, behavioral predispositions, and traumatic memories) and takes active, deliberate steps to alter the form, frequency, or situational context of these experiences, even when doing so causes behavioral harm or conflicts with long-term personal values. For example, an individual experiencing social evaluation anxiety who avoids attending career-advancing conferences is exhibiting experiential avoidance: the temporary relief from anxiety reinforces the avoidant behavior through negative reinforcement, while simultaneously eroding the person’s professional efficacy and long-term values.

Psychological Inflexibility and the Hexaflex Model

Psychological inflexibility represents the overarching transdiagnostic pathological umbrella within ACT, modeled through six interlocked pathogenic processes (the ACT “Hexaflex” in reverse):

• Cognitive Fusion: The tendency for humans to become entangled in verbal thoughts, treating cognitive evaluations, judgments, and self-criticisms as literal truths, imperatives, or physical threats rather than transient neurocognitive events. (Directly captured in AAQ-II items such as “I worry about not being able to control my worries and feelings”).
• Experiential Avoidance: The sustained effort to escape, numb, suppress, or modify private affective states, which paradoxically magnifies psychological suffering via cognitive rebound and heightened physiological sensitivity. (Reflected in “I’m afraid of my feelings” and “Emotions cause problems in my life”).
• Dominance of the Conceptualized Past and Feared Future: A loss of fluid, flexible contact with the immediate psychological and environmental present moment. Attention is excessively absorbed by rumination over past traumas or anticipatory catastrophizing about future distress. (Represented in “My painful experiences and memories make it difficult for me to live a life that I would value”).
• Attachment to the Conceptualized Self (Self-as-Content): Holding rigidly to an internal narrative about who one is (e.g., “I am broken,” “I am an anxious victim,” or “I am inadequate”), which limits behavioral exploration and novelty. (Exemplified by “It seems like most people are handling their lives better than I am”).
• Lack of Values Clarity or Contact: The inability to identify, connect with, or prioritize deeply held life directions, guiding ethics, and intrinsically rewarding chosen pathways, often substituting them with social compliance, external validation, or avoidance of immediate discomfort.
• Inaction, Impulsivity, or Avoidant Persistence: The behavioral breakdown characterized by lethargy, passive procrastination, compulsive escaping behaviors, or rigid behavioral repetitions that fail to produce vital living. (Measured in “Worries get in the way of my success” and “My painful memories prevent me from having a fulfilling life”).

The AAQ-II was empirically constructed as a unidimensional instrument to assess this singular, higher-order latent construct. When an individual achieves a high score on the AAQ-II, they are indicating that an extensive proportion of their behavioral energy is channeled toward combating, regulating, and evading internal distressing phenomena, leading directly to broad life disruption and compromised vital functioning.

Theoretical Framework

The theoretical architecture underpinning the AAQ-II is rooted in Functional Contextualism and Relational Frame Theory (RFT), a comprehensive, empirically supported post-Skinnerian account of human language and cognition pioneered by Steven C. Hayes, Dermot Barnes-Holmes, and colleagues.

Functional Contextualism

Functional contextualism is a modern philosophical viewpoint that analyzes psychological events as ongoing interactions between whole organisms and historically and situationally situated contexts. The fundamental truth criterion of functional contextualism is successful working (prediction and influence of psychological behavior with precision, scope, and depth). In alignment with this stance, the AAQ-II does not treat psychological events as inherently pathological structures residing inside a cognitive machine. Instead, it evaluates the function of psychological events in context: does the individual’s functional relationship to their thoughts and emotions support or undermine valued living?

Relational Frame Theory (RFT) and Derived Relational Responding

RFT demonstrates that the human capacity for complex symbolic language is driven by arbitrarily applicable relational responding (AARR). Humans learn to relate stimuli arbitrarily under contextual cues without direct physical conditioning (e.g., establishing relations of coordination, distinction, comparison, opposition, hierarchy, and perspective-taking). Crucially, through the transformation of stimulus functions, the emotional, somatic, and behavioral functions of one stimulus spontaneously transfer across relational networks to other derived stimuli.

Because of this linguistic capability, a simple, non-threatening situational cue can derivedly elicit intense conditioned terror or trauma-related sorrow simply by being verbally framed with past traumatic experiences. For human beings, the environment becomes saturated with verbally constructed threats. Natural animal avoidance (which is adaptive for surviving physical predators) transforms into internal experiential avoidance: humans attempt to apply external behavioral escape strategies to their own internal cognitive and emotional processes.

However, functional contextual research demonstrates that deliberate experiential avoidance is uniquely self-defeating due to two mechanisms:

1. The Paradox of Thought and Emotion Suppression: When an individual attempts to avoid thinking about or feeling an aversive private event, the verbal rule governing the avoidance (e.g., “Do not feel anxious”) contains the very stimulus function of the avoided event (“anxious”). Checking whether the suppression is successful requires monitoring for the presence of the forbidden event, which activates the relational network and causes a rebound of the targeted emotion or thought (Wegner’s ironic process theory).
2. Behavioral Constriction: To avoid situations that trigger painful derived thoughts and feelings, individuals steadily shrink their physical behavioral repertoires. They avoid social gatherings, career risks, physical intimacy, or physical activity, eventually finding their living environments severely constricted and isolated.

The AAQ-II operationalizes this theoretical mechanism, allowing contextual behavioral scientists to measure the degree to which an individual’s derived relational networks interfere with concrete, chosen values-directed actions.

Validity

The validity of the AAQ-II has been examined across hundreds of empirical studies involving clinical outpatients, university undergraduates, workplace samples, chronic pain populations, and substance-dependent cohorts worldwide.

Convergent Validity

The AAQ-II shows moderate to strong convergent correlations with a broad spectrum of psychopathology scales, negative affect measures, and clinical symptom checklists. In the original validation paper by Bond et al. (2011), involving 2,816 participants across six independent samples, the AAQ-II exhibited substantial positive correlations with:

• Depressive Symptoms: Beck Depression Inventory-II (BDI-II), yielding correlations ranging from $r = .65$ to $r = .71$ ($p < .001$).
• State and Trait Anxiety: State-Trait Anxiety Inventory (STAI-T), demonstrating correlations between $r = .58$ and $r = .68$ ($p < .001$).
• General Psychiatric Morbidity: General Health Questionnaire (GHQ-12), with coefficients consistently spanning $r = .55$ to $r = .66$.
• Perceived Stress: Perceived Stress Scale (PSS-10), correlating positively at $r = .60$ to $r = .67$.
• Thought Suppression: White Bear Suppression Inventory (WBSI), producing positive associations of $r = .50$ to $r = .63$.

Conversely, the AAQ-II exhibits strong negative associations with positive psychological functioning indices, including subjective well-being as indexed by the Satisfaction with Life Scale (SWLS; $r = -.45$ to $-.58$), positive affect on the PANAS ($r = -.42$ to $-.51$), and dispositional mindfulness on the Mindful Attention Awareness Scale (MAAS; $r = -.52$ to $-.61$) and Five Facet Mindfulness Questionnaire (FFMQ; $r = -.48$ to $-.64$).

Predictive and Incremental Validity

Bond et al. (2011) demonstrated that the AAQ-II possesses meaningful incremental predictive validity. In prospective longitudinal models, baseline AAQ-II scores predicted future mental health status and work absence over a 12-month period, even after controlling for baseline general mental health (GHQ-12) and trait affectivity. Across clinical intervention studies, reductions in AAQ-II scores across the course of Acceptance and Commitment Therapy mediate clinical improvements in posttraumatic stress disorder, generalized anxiety disorder, substance misuse, obsessive-compulsive spectrum presentations, and chronic pain disability, confirming its utility as a process-of-change metric.

The Construct Contamination Debate: Inflexibility or General Distress?

Despite its widespread adoption, the AAQ-II’s discriminant validity has faced intense academic scrutiny in recent psychometric literature. Prominent psychometricians and behavioral researchers (e.g., Wolgast, 2014; Tyndall et al., 2019; Rochefort et al., 2018) have argued that the AAQ-II suffers from substantial construct overlap with general psychological distress and trait neuroticism. Critical findings highlight that:

• Correlations between the AAQ-II and measures of neuroticism/negative affect (e.g., the NEO-PI-R Neuroticism domain or the DASS-21 Stress and Anxiety subscales) regularly reach or exceed $r = .75$ to $.85$, approaching levels that indicate collinearity.
• Item phrasings in the AAQ-II (such as “Emotions cause problems in my life” and “Worries get in the way of my success”) confound the functional response to internal distress with the intensity or frequency of the distress itself.

This debate has spurred the development of newer, process-pure instruments such as the Comprehensive assessment of Acceptance and Commitment Therapy processes (CompACT; Francis et al., 2016) and the Multidimensional Psychological Flexibility Inventory (MPFI; Rolffs et al., 2018). Nonetheless, the AAQ-II remains an exceptionally powerful behavioral predictor of negative functional trajectories across broad psychiatric domains.

Reliability

The psychometric evaluation of the AAQ-II demonstrates high internal consistency and stability across diverse empirical populations and language adaptations.

Internal Consistency

In the landmark validation study across six distinct sample cohorts ($N = 2,816$) conducted by Bond et al. (2011), the overall mean Cronbach’s alpha ($lpha$) was established at .88, with individual sample values ranging between .84 and .90:

• Undergraduate Developmental Sample 1 ($N = 653$): $lpha = .87$
• Undergraduate Replication Sample 2 ($N = 373$): $lpha = .88$
• Community and Workplace Sample 3 ($N = 502$): $lpha = .89$
• Cardiovascular Risk Healthcare Sample 4 ($N = 511$): $lpha = .85$
• Substance Misuse Clinical Outpatient Sample 5 ($N = 205$): $lpha = .87$
• Large Mixed Clinical Outpatient Sample 6 ($N = 572$): $lpha = .88$

Independent cross-cultural validation trials have replicated these findings. For instance, the Spanish adaptation (Ruiz et al., 2013) demonstrated an alpha of .91 in clinical samples and .88 in non-clinical cohorts; the Italian validation (Pennato et al., 2013) reported $lpha = .86$; the Dutch adaptation (Jacobs et al., 2008) yielded $lpha = .89$; and the Chinese version (Cao et al., 2013) produced $lpha = .88$. Composite reliability coefficients ($\omega$) regularly exceed .88, confirming that measurement error is minimal across the total score.

Temporal Stability (Test-Retest Reliability)

The longitudinal stability of the AAQ-II reflects its balance between trait-like stability in the absence of treatment and responsiveness to clinical intervention:

• Over a 3-month interval, Bond et al. (2011) observed a test-retest correlation of $r = .81$ ($p < .001$) in an untreated cohort.
• Over a 12-month interval, test-retest reliability remained robust at $r = .79$ ($p < .001$).

These temporal metrics confirm that psychological inflexibility operates as a stable, habitual behavioral style when unaddressed, while retaining sensitive dynamic responsiveness to targeted psychological interventions.

Factor Analysis

The factor structure of the AAQ-II was developed through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) across multiple independent cohorts during its construction.

Item Development and EFA

The revision process commenced with an initial pool of 10 candidate items generated by expert ACT clinicians and psychometricians, designed to represent the hexaflex model unidimensionally without the confusing, double-negative reverse-scored items that compromised the original AAQ-1. EFA conducted on early iterations using maximum likelihood estimation with oblimin and varimax rotations identified a dominant first factor accounting for over 50% of the common variance. Three items that demonstrated cross-loadings, floor effects, or ambiguous structural relations were eliminated, yielding the final 7-item instrument.

Confirmatory Factor Analysis (CFA)

Bond et al. (2011) tested the final 7-item set across multiple independent samples using CFA. The single-factor model demonstrated an outstanding fit across collegiate, community, workplace, and clinical cohorts. Exemplary goodness-of-fit indices reported across these developmental models include:

• Chi-Square / Degrees of Freedom: $\chi^2 / df$ ratios consistently falling between $1.82$ and $2.65$, well below the conservative threshold of 3.0.
• Root Mean Square Error of Approximation (RMSEA): Values ranged from .041 to .058, falling well within the standard criteria for good model fit ($< .06$).
• Comparative Fit Index (CFI): Values ranged between .96 and .98, exceeding the conventional .95 benchmark.
• Tucker-Lewis Index (TLI): Coefficients regularly registered between .95 and .97.
• Standardized Root Mean Square Residual (SRMR): Values ranged from .022 to .035.

Item Factor Loadings

All standardized factor loadings on the single latent “Psychological Inflexibility” construct are uniformly high, with no item displaying a loading below .60. Representative standardized factor loadings ($lambda$) observed across development samples are detailed below:

• Item 1: “My painful experiences and memories make it difficult for me to live a life that I would value.” ($lambda pprox .77$)
• Item 2: “I’m afraid of my feelings.” ($lambda pprox .78$)
• Item 3: “I worry about not being able to control my worries and feelings.” ($lambda pprox .80$)
• Item 4: “My painful memories prevent me from having a fulfilling life.” ($lambda pprox .82$)
• Item 5: “Emotions cause problems in my life.” ($lambda pprox .68$)
• Item 6: “It seems like most people are handling their lives better than I am.” ($lambda pprox .64$)
• Item 7: “Worries get in the way of my success.” ($lambda pprox .79$)

Subsequent Item Response Theory (IRT) analyses (e.g., using graded response models) indicate that the 7 items provide maximum test information and measurement precision in the moderate-to-high psychological inflexibility spectrum ($ heta$ values ranging from $0.0$ to $+2.5$), confirming that the tool is sensitive for identifying clinical vulnerability.

Instrument / Measurement Tool

The technical parameters and administration guidelines of the AAQ-II are structured as follows:

• Instrument Name: Acceptance and Action Questionnaire – II (AAQ-II)
• Authors: Frank W. Bond, Steven C. Hayes, Ruth A. Baer, Kelly M. Carpenter, Nigel Guenole, Holly K. Orcutt, Jennifer Waltz, and Robert D. Zettle
• Publication Date: 2011
• Construct Assessed: Psychological Inflexibility and Experiential Avoidance
• Administration Type: Individual or group self-report questionnaire (paper-and-pencil or digital administration)
• Completion Time: Approximately 1 to 3 minutes
• Target Population: Adolescents (ages 16+) and adults across clinical, research, and non-clinical populations
• Total Number of Items: 7 items
• Response Scale: 7-point Likert scale (1 = Never true, 2 = Very seldom true, 3 = Seldom true, 4 = Sometimes true, 5 = Frequently true, 6 = Almost always true, 7 = Always true)
• Reverse-Scored Items: None. All items are keyed in the direction of psychological inflexibility.
• Scoring Procedure: The total score is computed by summing the numerical ratings across all 7 items. The theoretical range is from 7 to 49. Higher aggregate scores indicate greater levels of psychological inflexibility and experiential avoidance, whereas lower scores reflect greater psychological acceptance, openness, and behavioral flexibility.
• Clinical Interpretation and Cutoff Scores: While the AAQ-II is primarily a continuous process measure rather than a categorical diagnostic test, empirical research suggests that scores above 24 to 28 indicate clinically meaningful levels of psychological inflexibility, elevated risk for clinical depression or anxiety disorders, and heightened functional impairment.

Permissions & Fee and Test Year

The Acceptance and Action Questionnaire – II was formally published in 2011 in the journal Behavior Therapy (Association for Behavioral and Cognitive Therapies). In alignment with the ethical principles and scientific values of the Association for Contextual Behavioral Science (ACBS), the AAQ-II is an open-access, public-domain instrument.

There are no licensing fees or royalties required for using the scale in non-commercial academic research, educational initiatives, or individual clinical practice. Researchers and clinicians are permitted to reproduce and administer the measure freely, provided appropriate citation is given to the seminal validation paper (Bond et al., 2011). Commercial digital health platforms or publishers seeking to package the instrument within proprietary commercial software systems should seek confirmation and guidance from the scale developers and the ACBS community.

References

• Bond, F. W., Hayes, S. C., Baer, R. A., Carpenter, K. M., Guenole, N., Orcutt, H. K., Waltz, J., & Zettle, R. D. (2011). Preliminary psychometric properties of the Acceptance and Action Questionnaire–II: A revised measure of psychological inflexibility and experiential avoidance. Behavior Therapy, 42(4), 676–688. https://doi.org/10.1016/j.beth.2011.03.007
• Cao, J., Ji, Y., & Zhu, Z. (2013). Reliability and validity of the Chinese version of the Acceptance and Action Questionnaire-Second Edition (AAQ-II) in college students. Chinese Mental Health Journal, 27(11), 873–877.
• Francis, A. W., Dawson, D. L., & Golijani-Moghaddam, N. (2016). The development and validation of the Comprehensive assessment of Acceptance and Commitment Therapy processes (CompACT). Journal of Contextual Behavioral Science, 5(3), 134–145. https://doi.org/10.1016/j.jcbs.2016.05.003
• Hayes, S. C., Strosahl, K. D., & Wilson, K. G. (1999). Acceptance and commitment therapy: An experiential approach to behavior change. Guilford Press.
• Hayes, S. C., Strosahl, K., Wilson, K. G., Bissett, R. T., Pistorello, J., Toarmino, D., Polusny, M. A., Dykstra, T. A., Batten, S. V., Bergan, J., Stewart, S. H., Zvolensky, M. J., Eifert, G. H., Bond, F. W., Forsyth, J. P., Karekla, M., & McCurry, S. M. (2004). Measuring experiential avoidance: A preliminary test of a working model. The Psychological Record, 54(4), 553–578. https://doi.org/10.1007/BF03395493
• Jacobs, N., Kleen, M., De Groot, F., & A-Tjak, J. (2008). Het meten van experiëntiële vermijding: De Nederlandstalige versie van de Acceptance and Action Questionnaire-II (AAQ-II). Gedragstherapie, 41(4), 349–361.
• Pennato, T., Berrocal, C., Bernini, O., & Rivas, T. (2013). Italian version of the Acceptance and Action Questionnaire-II (AAQ-II): Dimensionality, reliability, and validity. Journal of Psychopathology and Behavioral Assessment, 35(4), 552–563. https://doi.org/10.1007/s10862-013-9355-4
• Rochefort, C., Baldwin, A. S., & Chmielewski, M. (2018). Experiential avoidance: An examination of the construct validity of the AAQ-II and MEAQ. Behavior Therapy, 49(3), 435–449. https://doi.org/10.1016/j.beth.2017.08.008
• Rolffs, J. L., Rogge, R. D., & Wilson, K. G. (2018). Disentangling components of flexibility via the Multidimensional Psychological Flexibility Inventory. Journal of Contextual Behavioral Science, 7, 45–62. https://doi.org/10.1016/j.jcbs.2017.09.001
• Ruiz, F. J., Langer Herrera, A. I., Luciano, C., Cangas, A. J., & Beltrán, I. (2013). Measuring experiential avoidance and psychological inflexibility: The Spanish version of the Acceptance and Action Questionnaire – II. Psicothema, 25(1), 123–129. https://doi.org/10.7334/psicothema2011.239
• Tyndall, I., Waldeck, D., Pancani, L., Whelan, R., Roche, B., & Dawson, D. L. (2019). The Acceptance and Action Questionnaire-II (AAQ-II) as a measure of psychological inflexibility or neuroticism? A comprehensive evaluation. Journal of Contextual Behavioral Science, 12, 288–298. https://doi.org/10.1016/j.jcbs.2018.09.002
• Wolgast, M. (2014). What does the Acceptance and Action Questionnaire (AAQ-II) really measure? Behavior Therapy, 45(6), 831–839. https://doi.org/10.1016/j.beth.2014.07.002

Items of the Scale