Psychological flexibility refers to the ability to adapt to and cope with difficult or unexpected challenges, and has been linked to positive mental health outcomes such as resilience and the absence of symptoms (Kashdan & Rottenberg, 2010) as well as to academic and occupational success (Kercood et al., 2017). Flexibility has been defined as a core executive function (Diamond, 2013), with definitions of flexibility variously emphasizing cognitive, emotional and behavioral aspects (Cherry et al., 2021). These three aspects of flexibility (which are at times subsumed under the umbrella term “psychological flexibility”; Cherry et al. 2021) are not easily differentiated, as behavioral flexibility may be viewed as the observable manifestation of processes of cognitive and emotional flexibility. For example, Hohl and Dolcos (2024) define cognitive flexibility as “dynamic processes that allow adaption of our thinking and behavior [italics added] in response to changing contextual demands.”
Additionally, a lack of flexibility (i.e., rigidity) is reflected in the cardinal symptoms of many common mental health disorders listed in the DSM-5-TR (American Psychiatric Association, 2022). For example, the excessive feelings of guilt and worthlessness seen in major depressive disorder, the excessive and uncontrollable worries and avoidance seen in generalized anxiety disorder, the repetitive thoughts and behaviors of obsessive-compulsive disorder, and the restrictive, repetitive patterns of behaviors and interests seen in autism spectrum disorder can be interpreted as manifestations of cognitive, emotional or behavioral inflexibility. Similarly, personality disorders are described as rigid or inflexible ways of relating to the world despite negative consequences. While not yet reflected in the DSM, the widely-accepted reconceptualization of ADHD as a disorder of executive dysfunction (e.g., Brown, 2008) emphasizes the challenges with responding flexibility to task demands and with flexibly regulating emotions (van Stralen, 2016). This list is far from exhaustive, and is intended to illustrate that the diagnostic criteria for many DSM-5-TR disorders reflect a lack of flexibility as a central feature.
Given the centrality of inflexibility or rigidity in many mental health conditions, it is perhaps not surprising that many widely-used, empirically-supported therapeutic interventions aim to increase flexibility, and/or decrease rigidity, although may use different terminology for that goal. Additionally, while reliable, valid tools are available to measure flexibility, psychologists use these tools primarily for the diagnosis of cognitive disorders (such as ADHD or dementia) rather than to inform the treatment of disorders such as depression or anxiety. In the next section, I review several of these assessment tools, many of which measure flexibility as one of several executive functions (EFs). Then, I describe three empirically-supported treatments with a focus on flexibility (versus rigidity) as both a core vulnerability and a potential mechanism of change.
Assessment
Efforts to define and classify aspects of flexibility have led to the development of a number of assessment tools to quantify the construct, including both direct, performance-based measures and informant rating scales (Hohl & Dolcos, 2024). Performance-based measures such as the Delis-Kaplan Executive Functioning System (DKEFS; Delis et al., 2001) or the NEPSY-II (Korkman et al., 2012) use multiple tests to assess a range of EFs including cognitive flexibility. One drawback of these batteries is that performance on each test requires multiple EFs simultaneously (e.g., the DKES Tower Test requires cognitive flexibility as well as spatial planning and inhibition), such that low scores do not necessarily indicate deficits in flexibility specifically. Dann et al. (2023) reported that the Wisconsin Card Sort Test is the most widely used measure of cognitive flexibility, although they also note that (like the DKEFS) the WCST does not allow the psychologist to isolate cognitive flexibility from other cognitive functions such as working memory or inhibition. Despite their conceptual relevance, and validity for the diagnosis of neurocognitive disorders (e.g., dementia, ADHD, mild cognitive impairment), these performance measures have not been widely used to examine the effectiveness of psychotherapies that target flexibility. For example, administration of certain DKEFS subtests prior to treatment could identify clients low in flexibility, and repeated administration of the subtests after treatment could indicate whether flexibility increased as a result of treatment.
Additionally, a number of informant rating scales are available to assess flexibility, often as an aspect of overall EF. For example, the Behavioral Rating Inventory of Executive Functions, 2nd edition (BRIEF-2; Gioia et al., 2015) measures three major areas of EF (cognitive, emotional, and behavioral), with each area further divided into more narrow clinical scales. The BRIEF-2 scale that most closely assesses flexibility is the Shift Scale, described as measuring the ability to “move freely from one situation, activity, or aspect of a problem to another as the circumstances demand” (Gioia et al., 2015, p. 13). Interestingly, while this definition, and the wording of specific items within this scale, suggest a focus on behavioral flexibility, the scale loads on the Emotional Regulation composite. Other questionnaires to assess executive functions broadly (including flexibility) include the Comprehensive Executive Function Inventory (Naglieri & Goldstein, 2014), while those assessing cognitive flexibility specifically include the Cognitive Flexibility Inventory (CFI; Dennis & Vander, 2010) and the Cognitive Flexibility Scale (CFS; Martin & Rubin, 1995). While not widely used to examine the effectiveness of traditional psychotherapeutic interventions, measures such as the BRIEF-2 have been used to examine effectiveness of interventions for children and adolescents that target EF broadly and flexibility specifically (e.g., Kenworthy et al., 2013). In contrast, rating scales that focus narrowly on cognitive flexibility, such as the CFI and CFS, have been employed in many treatment-outcome studies cited below.
Finally, neurobehavioral measures of flexibility (especially cognitive flexibility) have been proposed including event-related potentials (ERPs; Zheng et al. 2024), neuroimaging (Uddin, 2024) and fMRI (Hohl & Doclos, 2024), although their validity as treatment-outcome measures has not been examined. Additionally, despite the potential for psychologists to assess flexibility using multiple methods, it is important to note the evidence for low convergent validity among such scores (for example, Bernes et al. (2021) and Johnco et al., (2014) report low correlations between self-report and neuropsychological measures of cognitive flexibility).
Treatment
In this section I describe three empirically-supported interventions through the lens of cognitive, behavioral, and emotional flexibility (versus rigidity), respectively.
Cognitive Behavior Therapy (CBT), an effective treatment for a range of mental health conditions (Cuijpers et al., 2023; Hofmann et al., 2013), is built on the assumption that many disorders such as depression and anxiety are caused and maintained by broad maladaptive beliefs (such as “I am unlovable”) that lead to specific negative thoughts that are automatic, firmly held, and thus rigid (inflexible; such as “He is going to leave me”). Through CBT, clients learn to think more flexibility (e.g., realistically or positively rather than negatively), and to behave more flexibly by engaging in rather than avoiding rewarding activities (i.e., behavioral activation); these changes result in improved mood and functioning (Hollon, 2020). Some research points to improved flexibility as a key mechanism of action for CBT (Akerblom, 2020).
In Acceptance and Commitment Therapy (ACT), psychological flexibility is a core concept, referring to the ability to adapt behavior (i.e., act flexibly) in ways that align with one’s values; clients are encouraged to notice their thoughts and emotions without rigidly acting on them (Fang & Ding, 2020; Hayes & Lillis, 2012). For example, a socially-anxious client who routinely avoids social situations, despite a desire (value) to have more friends, is encouraged to “commit” to social activities while noticing (not necessarily changing) their anxiety. In comparison to studies of CBT, research on the effectiveness of ACT often includes flexibility as a key treatment outcome, with some research further suggesting that changes in flexibility are a key mechanism of action in adults (Fleedderus et al. 2010; Scott et al., 2016) as well as children (Keinonen et al., 2023).
In Dialectical Behavioral Therapy (DBT), the key components of dialectical thinking (simultaneously holding two seemingly opposed perspectives, such as acceptance and change, or anger and love) and skills training (regulating emotions, tolerating distress, and managing relationships more effectively) reflect a primary focus on increasing flexibility and decreasing rigidity. Clients learn to be more emotionally flexible, through the use of skills that help them adjust their emotional response to fit situational demands; to think more flexibly, by recognizing multiple perspectives and avoiding rigid thought patterns (e.g., all-or-nothing thinking); and ultimately to use these tools to behave more flexibly in relationships (Linehan & Wilks, 2015). As with CBT and ACT, increases in psychological flexibility appear to be a key mechanism of DBT’s effects on symptom reduction (Gilbert et al, 2023).
In summary, decreased rigidity and increased flexibility are important therapeutic goals of interventions including CBT, ACT and DBT, and improvements in flexibility appear to account partially for their effectiveness; however, these treatments do not clearly distinguish among the cognitive, behavioral and emotional aspects of flexibility. Clinicians adopting an integrative approach may wish to use the terms “flexibility” and “rigidity” with their clients as a core construct that unifies many different therapeutic techniques.
Conclusion
By describing inflexibility (rigidity) as a common symptom of many common mental health conditions, and by noting that three widely-used and effective psychotherapeutic intervention share a goal of increasing flexibility, one could argue that flexibility is not only a core executive function, but a key feature of emotional resilience and mental wellness. Thus, efforts to increase flexibility, prior to the onset of diagnosable disorders, may have the potential to prevent, or lessen the severity of, many common mental health conditions (Biglan et al., 2008). There is emerging evidence among typically-developing children and adolescents that cognitive flexibility can be increased through short-term interventions, although questions about transfer and maintenance of gains linger (Buttelman & Karbach, 2017). Furthermore, efforts to bridge the gap between assessment and treatment of flexibility may help to identify clients for whom a therapeutic focus on flexibility is indicated (i.e., treatment moderators), and to document important mechanisms of therapeutic change (i.e., mediators).
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Mary Jo Coiro, PhD, ABPP
Board Certified in Clinical Child and Adolescent Psychology
Correspondence: MaryJo.Coiro@labschool.org