Final answer:
The dominant theoretical perspective in psychology until the 1950s was Behaviorism, spearheaded by John Watson and B.F. Skinner, focusing on observable behaviors and the environment's impact on them. However, dissatisfaction with behaviorism led to the emergence of humanistic psychology and the Cognitive Revolution, which reinvigorated the study of mental processes.
The correct option is B.
Step-by-step explanation:
The dominant theoretical perspective in psychology until the 1950s was Behaviorism. The core idea of this perspective was the focus on observable behaviors as the primary subject matter of psychology and the disavowal of studying unobservable mental processes. John Watson and B.F. Skinner were key figures in behaviorism, with Watson being known as its father and Skinner for his contribution to our understanding of operant conditioning. Behaviorism was characterized by its objective stance and the belief that all behaviors are determined by a combination of genetics and environment, thus rejecting the notion of innate personality traits.
Contrary to behaviorism, the humanistic approach, developed later by figures like Abraham Maslow and Carl Rogers, emphasized personal control, the potential for innate 'good,' and the importance of subjective experiences. Then, in the 1950s, the Cognitive Revolution began to bring attention back to mental processes, setting the stage for the rise of cognitive psychology, which focuses on thought in relation to behavior.