Nature: Habit memory is acquired subconsciously and slowly, by trial-and-error. It is more easily studied in animals than in humans, because of our strong tendency to acquire information as conscious (declarative) knowledge. Yet our capacity for unconscious learning is a vital aspect of the human condition, facilitating many routine tasks. Now it can be confirmed that humans do have a robust capacity for habit learning. Two patients with large medial temporal lobe lesions and profound amnesia were asked to acquire a task that is ordinarily learned by conscious memory. They learned gradually, in the way that monkeys learn the same task, and without being aware of what was being learned. The knowledge was rigidly organized, and performance collapsed when the task format was altered. Click here to read the story.