Kalisch et al. break a lance for more resilience-focused research and make the strong claim that positive appraisal style is the single mechanism that can prevent the development of stress-related disorders. We can only applaud a transdiagnostic approach that explicitly combines research on brain and behavior in a well-considered translational framework. We have a few comments, however, that may dampen some of the initial enthusiasm about this proposal. Our three main points concern the question of whether a focus on resilience will result in the anticipated paradigm shift, some methodological considerations, and the appropriateness of one, “all-in” resilience mechanism.

The authors' description of resilience inspired us to an analogy with human immunology. Resilience is defined as maintaining mental health despite exposure to stressors, and it can be seen as the analogue of actively preserving physical health despite exposure to pathogens such as bacteria or viruses. If we pursue this comparison, positive appraisal style would correspond to the human immune system, because the authors claim that this is the one, central resilience mechanism.

Our first main comment pertains to the desirability and de facto impact of radically focusing on resilience. In contrast to the authors' suggestion of a complete shift away from conventional disorder-focused research, we argue that it is important to understand the pathogen's mechanism of action in order to appreciate the immune response. In other words, we are advocates of complementary research strategies, exploring both vulnerabilities and resilience factors.

From a therapeutic point of view, it seems that this hand-in-hand approach may already have been set in motion. Over the past 15 years, several psychotherapeutic methods implicating positive (re)appraisal have been developed; for example, positive psychotherapy (Seligman et al. Reference Seligman, Rashid and Parks2006), well-being therapy (Fava & Tomba Reference Fava and Tomba2009), strengths-based cognitive behavioral therapy (Padesky & Mooney Reference Padesky and Mooney2012), and to a certain extent maybe even mindfulness (Segal et al. Reference Segal, Williams and Teasdale2002). (It is noteworthy that the neural correlates of mindfulness and cognitive reappraisal are virtually the same; Opialla et al. Reference Opialla, Lutz, Scherpiet, Hittmeyer, Jäncke, Rufer, Grosse Holtforth, Herwig and Brühl2014.) Interestingly, all these treatment strategies are being put forward as helpful adjuncts that should not necessarily stand alone, but may be integrated with other therapies. This indicates that the positive appraisal angle is valuable, but mainly as a complement to the traditional approach.

On top of that, psychopathology and resilience researchers will often (admittedly, not always) be looking at two sides of the same coin. For example, depressive rumination is characterized by an abstract processing style (i.e., thinking about the causes, meanings, and implications of an event). In line with this finding, recent studies have found that a concrete processing style (i.e., focusing on the specific perceptual details of an event) counteracts dysphoria (Watkins et al. Reference Watkins, Baeyens and Read2009) and depression (Watkins et al. Reference Watkins, Taylor, Byng, Baeyens, Read, Pearson and Watson2012). These examples illustrate that it seems advisable not to completely discard pathology research, but rather to combine it with the proposed resilience approach.

Our second main remark relates to some of the methodological innovations proposed by the authors. First of all, we are not sure whether abandoning self-report measures in laboratory settings, and replacing them completely with physiological or behavioral parameters, will prove to be a fruitful approach. Whereas physiological measures might have the advantages of being more objective and translatable to animal research, self-report-based measures provide valid information about the subjects' experience, which could be viewed as the ultimate criterion when aiming to improve mental health (Boddez et al. Reference Boddez, Baeyens, Luyten, Vansteenwegen, Hermans and Beckers2013b). Moreover, subjective measures might be useful in the investigation of high-level appraisal mechanisms, which appear to have neural correlates that differ from low-level mechanisms (Kalisch et al. Reference Kalisch, Wiech, Critchley and Dolan2006b).

In addition, we would like to scrutinize some of the laboratory procedures that the authors propose as examples of reappraisal. Although we recognize that an extinguished stimulus is ambiguous (Bouton Reference Bouton2002) and may be subject to appraisal, we would be wary of a priori equating extinction, a procedure in which the subject experiences that the outcome is changed externally, with a situation where the objective value of an event does not change (e.g., the sacked employee does not get his job back). The same holds for the counterconditioning procedures that the authors mention. We do not preclude that extinction or counterconditioning can be framed as reappraisal, but this awaits empirical demonstration; for example, by showing that extinction performance is affected by manipulation of the well-known appraisal dimensions. Given our consideration about the actual change of stimulus outcome, we suggest that it may be (more) interesting to focus on conditioning procedures in which the threat value of a stimulus is changed in the absence of new direct experience with this stimulus, the so-called retrospective revaluation procedures (e.g., backward blocking; Boddez et al. Reference Boddez, Baeyens, Hermans, Van der Oord and Beckers2013a).

Our third main point concerns the potential risk of putting all one's eggs in the same positive appraisal basket, and this for at least two reasons. First, even though it may be meaningful to look for general, integrative principles (Meiser Reference Meiser2011), a priori focusing on only one overarching mechanism can make researchers lose sight of other important resilience (sub)mechanisms that may prove instrumental in the development of new treatment options. Two promising examples of such (sub)mechanisms are memory and attention. Pilot data suggest that memory specificity training reduces depressive symptoms (Raes et al. Reference Raes, Williams and Hermans2009). In addition, positive mood produces a broadening of attention that may play an important role in the resilience against stressful events (Grol et al. Reference Grol, Koster, Bruyneel and De Raedt2014). Kalisch and colleagues can of course claim that these factors have an effect because they converge to positive appraisal; but in such argumentation, appraisal itself becomes an explanandum, again underlining the importance of other, explanatory (sub)mechanisms. In this regard, we also fear that broadening the definition of positive appraisal to a point where it includes everything would render it a useless concept.

Second, we argue that it might sometimes be worthwhile to look for resilience mechanisms that may protect only against specific pathological processes (Rutter Reference Rutter1993). For example, strong perceptual discrimination abilities may protect against overgeneralization (Lommen & Ehlers Reference Lommen and Ehlers2014), but not against any pathological process. Or, if we return to our immunology analogy: Just like the development of highly specific vaccines has been of vital importance to improving immunity to particular diseases, it may be valuable to not exclusively focus on general protective mechanisms.