Generalization of conditioned fear is adaptive in some situations but maladaptive when fear excessively generalizes to innocuous stimuli with incidental resemblance to a genuine threat cue. Recently, empirical interest in fear generalization as a transdiagnostic explanatory mechanism underlying anxiety-related disorders has accelerated. As there are now several studies of fear generalization across multiple types of anxiety-related disorders, the authors conducted a meta-analysis of studies reporting behavioral measures (subjective ratings and psychophysiological indices) of fear generalization in anxiety-related disorder vs. comparison groups. We conducted systematic searches of electronic databases (conducted from January-October 2020) for fear generalization studies involving anxiety-related disorder groups or subclinical analog groups. A total of 300 records were full-text screened and two unpublished datasets were obtained, yielding 16 studies reporting behavioral fear generalization measures. Random-effects meta-analytic models and meta-regressions were applied to the identified data. Fear generalization was significantly heightened in anxiety-related disorder participants (N = 439) relative to comparison participants (N = 428). We did not identify any significant clinical, sample, or methodological moderators. Heightened fear generalization is quantitatively supported as distinguishing anxiety-related disorder groups from comparison groups. Evidence suggests this effect is transdiagnostic, relatively robust to experimental or sample parameters, and that generalization paradigms are a well-supported framework for neurobehavioral investigations of learning and emotion in anxiety-related disorders. We discuss these findings in the context of prior fear conditioning meta-analyses, past neuroimaging investigations of fear generalization in anxiety-related disorders, and future directions and challenges for the field.
