The scanning technology allows us to pinpoint, usually within one cubic millimeter, where particular neural activity is taking place. This research has shown that the categories we form are real, biological entities, with specific locations in the brain. That is, specific and replicable regions of the brain become active both when we recall previously made categories and when we make them up on the spot. This is true whether the categories are based on physical similarities (e.g., “edible leaves”) or only conceptual ones (“things I could use as a hammer”
