Geo informed his current therapist, Dr. Volkov, that since his visit to the Grand Canyon, he has experienced such an intense fear of heights that he can no longer drive to his job, which requires him to cross a bridge. After realizing that Geo almost suffered a fall while at the Grand Canyon, Dr. Volkov concluded that Geo’s fear of heights must be associated with his near-fall experience. Dr. Volkov’s conclusion best relates to which early approach to psychology?