What Is Curiosity? From the first pages of the first book, Harry is gripped by a powerful urge to fnd out more. He asks questions, explores the environment around him, closely observes interesting phenomena, and dwells on complex events that he doesn’t fully understand. All of these are con- sidered by psychologists to be manifestations of curiosity. But notice that asking questions, venturing into forbidden spaces, and jumping on brooms are all behaviors that express curiosity, while the thoughts and feelings Harry has while lying in his bed are just that—internal experiences. One of the interesting ambiguities of curiosity is that it is both an internal experience and a set of behaviors. Daniel Berlyne, the first psychologist to empirically investigate curiosity, wanted to capture the nexus between the internal feeling, the behaviors that resulted from the feeling, and the features of the environment that elicited both feeling and behavior. His studies, done in the early six- ties, showed that when a person encounters surprise, novelty, and complexity, he or she experiences arousal, which leads to explora- tion. In one of the first experiments involving humans, Berlyne asked subjects long lists of questions about invertebrates and also asked them to rate the questions in terms of how surprising and interest- ing the questions were. Then subjects were given long lists of ran- domly ordered answers to those questions. Finally, they were given the original questionnaire a second time. Just as Berlyne predicted, subjects were more able to answer those questions they had rated Harry’s Curiosity as surprising or engaging. Berlyne concluded from this that when a subject confronts surprise, he or she is aroused. Getting the answer to a surprising question reduces that arousal. This arousal reduction, which feels good, reinforces the subject’s learning of that item. When Harry is asked at Hogwarts to learn about the study of magical plants, the very possibility that plants are magical surprises him. We can pre- dict, based on Berlyne’s work, that Harry will learn the information better because the topic is unexpected and novel. Berlyne’s work un- derscores the fact that curiosity is both invisible (an internal feeling) and visible (a behavior).