Meta-analyses have become foundational tools for evidence synthesis and are receiving increasing attention across research disciplines, including fear conditioning - a central paradigm in affective, behavioral, and clinical neuroscience and psychology - where the number of meta-analyses has notably increased in recent years. However, substantial methodological heterogeneity among these meta-analyses complicates their interpretation and comparability.This review systematically summarizes existing meta-analyses in fear conditioning (n = 26), with particular emphasis on methodological choices and reporting standards. Our findings indicate substantial variability in reporting practices, particularly regarding review processes, applied methodological models, and the operationalization of certain variables, which may challenge reproducibility and interpretability. Most meta-analyses used aggregate data and random-effects models, while moderator analyses were frequently conducted but yielded few significant moderators. Outcome measures were frequently aggregated (e.g., skin conductance, startle responses, ratings) without a clear theoretical rationale.We discuss the implications of moderator analyses, the limited attention to temporal dynamics, and the aggregation of diverse outcome measures. We argue that the field would benefit from more precise reporting, theory-driven analytical decisions, and increased data sharing at both the primary and meta-analytic levels. Such improvements would facilitate individual participant data meta-analyses, which preserve within-study variability, enhance moderator analyses, and address challenges inherent to aggregate-level data synthesis. Establishing and expanding shared infrastructures represents a necessary step toward cumulative, reproducible, and clinically informative work in the future.
Category-based fear generalization refers to the extension of acquired fear responses to novel stimuli sharing categorical cues with a threat stimulus. Categories are organized into superordinate, basic-level, and subordinate levels, which differ in cognitive processing advantages; however, whether this categorical advantage influences fear generalization remains unclear. Experiment 1 used a discriminative fear conditioning paradigm, employing subordinate exemplars of birds and measuring tools as the threat-conditioned stimulus (CS+) and the safety-conditioned stimulus (CS-), respectively. During the generalization test, we included generalization stimuli sharing either the same basic-level category (GSBasic) or the same superordinate category (but different basic-level category) as the CS+. Fear generalization was assessed via shock expectancy ratings and skin conductance responses. Experiment 2 manipulated CS+ diversity (high vs. low) in the same task while recording electroencephalography to examine its moderating role. Behaviorally, acquired fear generalized more robustly to GSBasic than to GS sharing the same superordinate category (GSSuperordinate). Participants in the high-diversity group showed higher shock expectancy ratings for both the CS+ and GSBasic than those in the low-diversity group. Event-related potential results revealed that GSBasic elicited P2 and N400 amplitudes comparable to those of the CS+, and exhibited more positive P2 and less negative N400 amplitudes than GSSuperordinate and CS-. Moreover, only the CS+ and GSBasic elicited more positive LPP amplitudes than CS-. These findings suggest that early attentional allocation, late semantic processing, and motivational attention collectively constitute the electrophysiological basis of the basic-level category processing advantage in fear generalization, offering implications for the intervention of anxiety disorders.
Childhood trauma has been identified as a major risk factor for the development of fear-related disorders in adulthood. Exposure to trauma might impact fear learning and extinction processes, which in turn may increase risk for these disorders. A PubMed, PsycInfo, and Web of Science search was conducted through May 6, 2025. Studies that used classical fear conditioning paradigms, measured indicators of fear response, examined childhood trauma or maltreatment in populations aged 18 or younger were included. Effect sizes were calculated for response to threat cues, response to safety cues, and differential fear response during acquisition and extinction, if included. Ultimately, 14 studies met the criteria for the qualitative review and 12 were quantitatively meta-analyzed (aggregate n = 1094). Results showed that trauma exposure was significantly associated with blunted responses to the threat cue during early acquisition when compared to children with little or no trauma exposure (g = −0.40; p < 0.01; k = 4). When assessing trauma exposure continuously, greater trauma exposure was significantly associated with lower responding to the safety signal (r = −0.10; p < 0.05; k = 8) and more pronounced discrimination (r = 0.15; p < 0.001; k = 8) in early acquisition. No significant effects were observed for extinction albeit studies were limited (k = 4). Findings suggest that trauma-exposed children exhibit altered fear learning patterns during acquisition. Future research should examine the impact of early life trauma on the development of fear learning and potential for acquiring fear-related disorders into adulthood.
Social learning, such as learning through verbal instruction, has been proposed to play a crucial role in the development pathological fear of bodily sensations. Despite the ubiquity of verbal information in daily life, the effects of verbal information on subsequent interoceptive fear learning remain empirically untested. Therefore, we aimed to examine how verbal information about the threatening vs. benign nature of bodily sensations influences subsequent interoceptive fear conditioning. 77 healthy participants were randomly assigned to receive either threat- or safety-enhancing information about bodily sensations before completing an interoceptive fear acquisition and extinction task. Two geometric symbols served as CSs and temporary dyspnea (inspiratory load) as the US. Verbal reports indicated successful differential learning in both groups, with no modulation of information type. However, participants of the threat information group showed no differential response in startle response magnitudes towards CS + relative to CS-, indexing that the activation of brain defensive networks, that did not differ between CS+ and CS-. This pattern might suggest a generalization of, or failure to inhibit defensive activation toward the safety stimulus. In contrast, the safety information group exhibited significantly smaller startle response magnitudes towards CS- vs. CS+, indicating preserved differentiation between threat and safety. No group differences emerged during the extinction phase. Despite the preliminary nature of our findings, the pattern of results demonstrates interaction of different fear learning pathways in shaping the risk for the development of pathological fear and anxiety.
