Final answer:
Abraham Maslow was not a behaviorist; he is recognized for his humanistic approach, particularly Maslow's hierarchy of needs, which deviates from the behaviorist focus on purely observable behaviors.
Step-by-step explanation:
The psychologist among the provided options who was not a behaviorist is Abraham Maslow. While Edward Thorndike, John B. Watson, and B. F. Skinner were all known for their contributions to the school of behaviorism, Maslow is famous for proposing the theory of human motivation known as Maslow's hierarchy of needs, which is more aligned with humanistic psychology rather than behaviorism. This concept highlighted stages of growth in humans and contradicted the behaviorists' focus on behavior as the sole determinant of personality.