Final answer:
Behaviorists strongly emphasized the study of overt behavior, focusing on observable actions and disregarding internal mental processes.
Step-by-step explanation:
The behaviorists were primarily interested in the study of overt behavior, which is the visible or external behavior of an individual rather than the internal states or mental processes. Overt behavior is something that can be directly observed and recorded by others, making it an ideal focus for behaviorist research and theories.
John B. Watson, a prominent figure in behaviorism, emphasized the prediction and control of behavior as opposed to understanding the internal mental states. B.F. Skinner, another key behaviorist, furthered this perspective through his work on operant conditioning, which is a learning process that involves the modification of behavior through the use of reinforcements and consequences.