Watson and Behaviorism
Much of Psychology focuses on how the environment affects behavior - how learning alters behavior. Some use animals to further our understanding of learning, while others study humans. The foundations of this approach emerged relatively early on in the history of psychology. Watson (1878-1958) introduced the behaviorist approach or behaviorism in about 1913. He believed that psychologists must study behavior - even though psychologists seek to understand the processes that underlie behavior, they must focus on behavior in their studies - otherwise, research can't be objective.
According to the dictionary, "objective" means "..dealing with outward things or exhibiting facts uncolored by feelings or opinions." Reliance on self-report, for example, will always be subjective. The earliest psychologists, unfortunately, did not use objective methods. Wilhelm Wundt is given credit for establishing the 1st Psychology lab, but employed the highly subjective process of introspection. Watson (the "father" of behaviorism) believed that if we understand the basic laws of learning we will be able to understand and explain behavior. Watson's work was largely influenced by Pavlov. Pavlov studied classical conditioning (CC). CC is a primitive form of learning and one that can be demonstrated in most any species. So, the name we first think of when discussing behaviorism is Watson, who was largely influenced by Pavlov. Skinner was another behaviorist - one who extended Watson's approach. He was interested in the impact of learning on behavior, but he focused not on the association of two stimuli (as is the focus of CC), but on how the consequences of a behavior influenced the probability of engaging in the behavior again. In other words, his interest was in how reward and punishment alter behavior. He developed the "Skinner box." And his real interest was in what came to be called operant conditioning. An animal acts on, operates on the environment, and the outcome of this determined whether or not the behavior will be engaged in again.
Note that it was not until the latter part of the 19th century that scientific psychology was born. Prior to this time, the basic ideas of some areas and interests of psychology existed, but psychology had not yet evolved into a science. Attempts to explain the differences in human behavior existed, but none that stood up to experimental scrutiny. One interesting example is phrenology. What do those bumps on your head really mean? Do they have meaning?
The fundamental idea behind the introduction of psychology as a science was that mind and behavior – like planets or chemicals or human organs – could be the subject of scientific analysis. Today's psychology is based on experimental evidence. Psychology is a science and, like all sciences, it progresses as new data is collected and new discoveries are made.