History of ABA
Behavior Analysis has 3 branches:
Behaviorism:
Behaviorism focuses on theoretical and philosophical issues. The principles are used to guide behavior analysts as the experiment and practice of ABA

Experimental Analysis of Behavior (EAB):
EAB is the basic research done in laboratory settings with both human participants and non-human subjects with the goal of discovering fundamental principles of behavior.
Applied Behavior Analysis (ABA):
ABA focuses on solving problems of social importance using the principles and procedures of behavior analysis.
Behavior analysis began as a subfield within the discipline of psychology. In the early 1900s, psychology was dominated by the study of states of consciousness, images, and other mental processes. However, in 1913 John B. Watson wrote an article which argued that the proper subject matter in psychology was observable behavior, not states of mind or mental processes. He also argued that the objective study of behavior as a natural science should consist of direct observation between environmental stimuli (S) and the responses (R) they evoke.


B.F. Skinner formally began the experimental branch of behavior analysis which expanded the field of behaviorism originally described by Watson. Skinner explained the distinction between respondent conditioning (conditioned reflexes) and operant behavior (the consequences of behavior controls the future occurrence of the behavior).
References
Cooper, J. O., Heron, T. E., & Heward, W. L. (2007). Applied behavior analysis.
Fisher, W. W., Piazza, C. C., & Roane, H. S. (Eds.). (2013). Handbook of applied behavior analysis. Guilford Publications.
Miltenberger, R. (2011). Behavior modification: Principles and procedures. Nelson Education.