‘The surprising thing about learning’ considers the second key question about learning: what is the nature of the mechanism that allows learning to take place? It first looks at the phenomenon of blocking and then considers the factor of surprise? Surprise is when there is a difference between what you expect to happen and what actually happens. It is one of the most important concepts in learning. It allows learning to be selective: organisms will not blindly associate any events that happen to co-occur. Instead animals restrict their information gathering to circumstances in which there is a difference between what is expected, and what is actually obtained.