In a recent laboratory study, researchers made participants smell a variety of odors and rate them as good, bad or neutral. Then, they exposed them to disturbing pictures and stories of war and car crashes, in order to induce anxiety. After that, they reintroduced the neutral odors. In their anxious states, the participants reported that those formerly neutral odors now smelled bad. Functional brain scans revealed that two independent brain circuits were lighting up together: one associated with smell, and one devoted to emotion. Typically, only the smell circuits are involved in odor processing, but it seems that when we’re dealing with anxiety, our emotions become intertwined with perception, darkening our view—or rather smell—of the world.