John B. Watson is known for studying how individuals respond to external stimuli in 1913. He focused more on the external reactions because this was visible unlike emotions which are internal reactions. He did an experiment where he had a 9 month old infant be introduced to a variety of animals and objects to which the infant showed no fear to these items. He later discovered that by banging a steel bar when a rat was presented to the infant the infant began to experience fear so whenever he saw the rat he had an external negative reaction. He believed that a change in environment can cause an individual to have a certain reaction associated to that change. His findings can assist in being able to create  positive environments for individuals like students. If a classroom for example is always dark and the desks are arranged in a way that doesn't allow for interactions with others the students will feel less inclined to participate and their learning is affected because the environment is not a positive one that encourages learning. We can observe the external response of an individual to evaluate any changes that need to be made, paying close attention to the environment and connection to specific responses.