When I was small, telling my mother I was hungry did not always mean I was getting food. Sometimes I would say: “Mummy, I’m hungry .” And she would say: “Go and drink water first.” I hated that answer. I had said hungry. She had heard water. At the time, it felt like she was ignoring the simple information I had just given her. Years later, I came across a mouse experiment that made me think about that exchange differently. Not because my mother had somehow discovered neuroscience. She hadn't. But because the experiment revealed something strange: A real physiological need does not always produce a perfectly matched choice. The experiment In a 2021 Nature Neuroscience study , researchers gave mice choices between food and water while manipulating whether the animals were hungry or thirsty. Sometimes, thirsty mice chose food. The mice weren't pretending to be thirsty. They were thirsty. The surprising part was that their physiological state did not always produce the behaviour t...