Understanding why some people develop anxiety disorders while others remain resilient may hinge on how quickly the brain's alarm system learns to calm down. This neuroimaging discovery reveals a fundamental difference in how uncertainty-sensitive individuals process repeated emotional encounters, with implications for anxiety prevention and treatment approaches. Researchers tracked amygdala activity—the brain's threat-detection hub—in 85 participants during repeated exposure to emotional faces using fMRI scanning. They measured 'habituation slopes,' indicating how rapidly amygdala activation decreased with repeated presentations. Individuals with high intolerance of uncertainty showed significantly flattened habituation curves, meaning their amygdala remained hyperactive even after multiple exposures to the same emotional stimuli. Conversely, those comfortable with uncertainty demonstrated steep habituation slopes, with amygdala responses quickly diminishing over time. This neural adaptation difference persisted even after controlling for general anxiety traits, suggesting uncertainty sensitivity operates through distinct brain mechanisms. The finding illuminates why emotional faces—which carry inherent social ambiguity about intentions and reactions—trigger sustained vigilance in uncertainty-intolerant individuals. This represents a crucial advance in anxiety research, moving beyond broad personality traits to identify specific neural vulnerabilities. The impaired habituation pattern may explain why some people remain perpetually on edge in social situations while others quickly adapt. For longevity-focused adults, this research suggests that cultivating uncertainty tolerance through mindfulness practices or cognitive training might literally rewire threat-processing circuits. The findings also hint at personalized intervention strategies: individuals showing poor neural habituation might benefit from extended exposure therapies, while those with intact habituation might respond better to brief, intensive approaches.