“Think of a white sandy beach on a paradise island. Can you see it?” The ability to visualize a place, object, or place on request varies significantly between individuals. But some people cannot conjure up mental images at all: this trait is known as aphantasia, literally “a defect of imagination.” Aphantasia is not a disorder of the mind but an astonishing cognitive peculiarity that could help us understand how visual mental imagery works. At Paris Brain Institute, Jianghao Liu and Paolo Bartolomeo (Inserm) have shown that people with aphantasia have characteristics that can be described objectively: they are slower than average at processing visual information and have difficulty absorbing it. These observations are described in a recent study published in the journal Cortex.