Final answer:
The claim that humanist psychology has untestable assumptions is true. The approach focuses on in-depth human experiences and promotes innate capacities for change, exemplified by theories such as Maslow's hierarchy of needs, but lacks empirical testing due to its subjective concepts.
Step-by-step explanation:
A major criticism of humanists psychology is that many of its assumptions are untestable. This statement is indeed true. Humanist psychology, emerging as a "third force" in psychology, was a reaction to both the psychoanalytic perspective and behaviorism. It sought to recognize the depth and meaning of human experience and the innate capacity for self-directed change. One notable humanist, Abraham Maslow, proposed the widely recognized hierarchy of needs theory. However, the humanist approach has been criticized for its lack of empirical rigidity. For example, concepts like self-actualization are difficult to define and measure objectively, making empirical testing challenging.