To date, most research on psychological resilience has identified individual biopsychosocial factors associated with this construct but has not investigated how these factors relate to one another and what common mechanisms may mediate their impact (Southwick & Charney Reference Southwick and Charney2012). Kalisch et al.'s ambitious “A Conceptual Framework for the Neurobiological Study of Resilience” makes an important contribution to the literature by proposing a comprehensive, theory-driven, and integrated approach to studying resilience. We agree with many points made by the authors, including: (1) the need for coherent and integrated models of resilience; (2) the limitations of a categorical versus dimensional and transdiagnostic approach to operationalizing resilience; (3) the need to assess a broad range of stressors and traumas when studying resilience; and (4) the importance of longitudinal studies.

In this commentary, we raise four issues for the authors to consider.

First, according to the authors, positive appraisal style is “the common resilience mechanism onto which all resilience factors converge and through which they exert their protective effects on mental health” (Table 1 of the target article). Although a substantial body of evidence does point to the resilience-enhancing effects of positive appraisal, negative appraisal (e.g., ability to detect and respond to danger) is also critical for resilience and survival. Positive attention or appraisal draws animals and humans toward stimuli that are pleasurable and rewarding and that sustain life, whereas negative attention or appraisal directs them away from threats and dangers. Both are essential to maintaining resilience.

In our view, both excessively negative and excessively positive appraisal and reappraisal styles can compromise resilience. On the one hand, as noted by the authors, when people with an excessively negative appraisal and reappraisal cognitive style face challenges, they typically overestimate the likelihood or magnitude of a negative outcome, or they underestimate their capacity to cope – or both. On the other hand, an excessively positive style can lead to inadequate preparation as the result of an underestimation of risk and an overestimation of ability (Schneider Reference Schneider2001). For example, as noted by Schneider (Reference Schneider2001, p. 250), overly positive appraisals may “involve self-deception or convincing oneself of desired beliefs without appropriate reality checks.” Similarly, it follows that higher appraisal scores (i.e., AS, continuous index of appraisal style) do not necessarily translate to greater levels of resilience, because the relationship between AS and resilience is likely curvilinear. Accordingly, we suggest that resilience can be fostered by appraisals and reappraisals that are generally positive but also accurate and realistic, which lead to stimulus-appropriate responses.

Second, the authors propose that resilience be operationalized as a continuous quantitative outcome. Complex adaptive systems do not always change in a linear manner, however. Thresholds abound in nature, from coral reefs (Fung et al. Reference Fung, Seymour and Johnson2011) to brain circuits (Dietrich & Horvath Reference Dietrich and Horvath2011) to psychological performance (Dutilh et al. Reference Dutilh, Wagenmakers, Visser and van der Maas2011; Krystal Reference Krystal1978); and when a threshold is crossed, a phase transition may take place that makes crossing back difficult or impossible because the system has undergone a fundamental change, a property known as hysteresis (Walker & Salt Reference Walker and Salt2006). For example, an athlete may positively appraise his capacity to endure intense physical challenges, such as running marathons. But he may be unaware that his coronary arteries have gradually become occluded, until one day he has a massive heart attack, at which point he crosses a threshold and becomes far less physically and likely psychologically resilient. One definition of resilience is “the capacity to absorb disturbance; to undergo change and still retain essentially the same function, structure and feedbacks, without crossing a threshold to a different system regime – a system with a different identity” (Walker & Salt Reference Walker and Salt2006, p. 32). Applying this definition, resilience involves knowing where one's thresholds may lie and distance from these thresholds, understanding the primary drivers that cause the system or individual to cross a threshold, and finding ways to move the threshold or move away from it.

Third, by the authors squarely placing resilience in the individual and considering socioenvironmental factors as “distant influences” on mental health, we believe they underestimate the importance of complex linkages of individuals, families, communities, cultures, and the environment in fostering resilience. These systems and linkages are constantly adapting to change and interacting with one another. Although promoting positive cognitive appraisal/reappraisal style in the individual is important, we believe that it is critical to also intervene at other levels. For example, the most effective way to enhance resilience in children involves providing a safe, stable, and loving environment (Masten Reference Masten2014). Accordingly, resilience-enhancing interventions for children might include affordable housing, safer neighborhoods, better schools, and classes in effective parenting.

Fourth, the authors' idea that resilience research “should focus not on any specific dysfunction or pattern of dysfunction but on global or average dysfunction” (sect. 1.4, para. 1) contrasts with a substantial literature on learning and the utility of assessing and fostering specific strengths and domains of functioning. For example, scenario-based training (Salas et al. Reference Salas, Priest, Wilson, Burke, Adler, Castro and Britt2006), a highly realistic form of training where the individual receives real-time constructive feedback while practicing a specific skill or set of skills, is one of the most effective ways to learn, and is essential for training firefighters, police officers, and soldiers. Although interventions to enhance overall well-being, such as exercise, meditation, and improved sleep hygiene, are known to enhance one's capacity to deal with stress (Southwick & Charney Reference Southwick and Charney2012), equally important are person-specific interventions, similar to personalized medicine.

The notion that resilience is not simply the absence of vulnerability, but instead a positive attribute that can be characterized, studied at a mechanistic level, and taught is, in its own way, a recent and revolutionary idea. We applaud the efforts by Kalisch et al. to advance a formal model for resilience that is grounded in cognitive neuroscience and that has a number of broad implications for the field of stress. In this commentary, we highlighted a number of directions that might be pursued in the further development of this and other models for resilience. It is critical that we progress in this area of research in order to prevent and alleviate suffering in people who, all too commonly, confront extreme challenges to their well-being.