All this happened, more or less.

After exchange of the usual niceties, I asked him [Skinner] why he had chosen psychology. His reply surprised me, br Skinner said that as an undergraduate he had no interest in psychology. His ideal was to change the world and he thought this was best accomplished by writing - Sartre came to the same conclusion. After he read John Watson's book On behaviorism, however, Skinner changed his mind and decided that psychology was the better strategy to achieve that prized goal. ibid. 137.