Most researchers believe that memory is not a unitary phenomenon. There are a variety of memory systems that are subserved by a number of different neural systems within the brain. Learning- is a relatively permanent change in behavior as a function of experience. Learning is demonstrated by an organism demonstrating a change in behavior as a result of experience or showing that the organism recalls of remembers these experiences and changes its behavior accordingly. Learning and memory are two sides of the same coin- experience-dependent behavior. Studies of both learning and memory are inferential that is we watch the behavior and infer that someone is learning or remembering on the basis of what the person does.