A theory of learning, or behavior, in terms of human development, follows the idea that psychology should focus on behavior, the way we act. A behaviorist places value on attributes that one can see and therefore study, as opposed to invisible attributes, such as thinking, feeling, and other brain activities that occur without one even knowing it (Craig and Dunn, 2010, p. There are three important modern theorists of behavior or learning: Ivan Pavlov, John Watson, and B.F. Skinner. However, as William Crain stated, John Locke was the "father of environmentalism and learning theory", although Ivan Pavlov and B.F. Skinner were his "heirs" (Crain, 2011 p.3 ). To some, behaviorist theories may seem restrictive or incomprehensible, but it is clear that all major theories play a role in our understanding of development. British philosopher John Locke developed theories in the late 17th century that the child has no intrinsic beliefs. or understanding concepts until the child has experienced these things for themselves. He claimed in his writings that through observation of children's behavior, children are like an empty, unfurnished room whose furniture can be chosen, especially in the early years when children are most responsive to suggestions and comments (Crain, 2011). Locke believed that environment was an essential factor in development, but he also saw that the way one gives feedback to a child also affects his behavior. Crain (2011) noted that Locke believed it was important to facilitate a child's good health and that beyond that, adults should help reinforce children's behavior through rewards and punishments . More than two hundred years later, BF Skinner understood the importance of reward and punishment. punishment while he studied opera...... middle of paper ...... Tson's later innovations were to remove or decondition fears, by introducing the feared object very slowly, in a slow manner , progressive and sure until the object no longer evokes a fearful response (Crain, 2011). All of these behavior and learning theorists have made enormous strides in understanding the psychology of human development through a rigid set of principles, through research experiments, observation, and behavior modification. We can be put off by the inflexible denial of cognitive processes in behavior and in the relationship to development. Certainly, many theories and theorists have made progress in bridging the gap between behavioral and environmental-only theories and cognitive theories. We must not lose sight of the fact that all of these major theorists have made valuable contributions to our vision of human development, including these staunch behaviorists..