Second, members of his intellectual group of friends, which included Robert Yerkes, Herbert Langfeld, and Ralph Barton Perry, left Cambridge or withdrew for familial reasons.
Heft (2001) has also suggested that Holt's homosexuality might have generated some further conflicts in Cambridge in the early decades of the 20th century.
After attending Sigmund Freud's famous lecture in Clark University in 1909, Holt was highly impressed with psychoanalysis, which influenced his book The Freudian Wish.
Holt's psychology was related to the behaviorism of Watson, but his views about behavior were broader and more philosophically oriented than Watson's, including for instance notions such as goals, purposes, and plans, clearly observable in the actions of organisms (See discussions in Charles, 2011).
After his retirement, Holt moved to Tenants Harbor, Maine, with his long-time male companion, George X. Bernier.