But how does our brain know what’s real and what’s not? When someone saw real projected lines, activity in the fusiform gyrus was stronger than when they knew they were simply imagining the diagonal lines. However, when someone confused imagined lines for real ones, essentially having a mild hallucination, both the fusiform gyrus and anterior insula regions lit up—as if they’d seen the real thing. While participants lay in an fMRI scanner imagining sets of diagonal lines, Dijkstra secretly projected real lines using a mirror to compare brain activity. When she first moved to London from the Netherlands, Dijkstra saw a creature in the distance while walking in her neighborhood.