In Dumbo Timothy Mouse implants an idea into the ringmaster’s mind by talking to him in his sleep:
He explicitly says: “I am the voice of your subconscious mind. Your inspiration.”
What would this have meant to Disney’s audience in the early 1940s? Of course, his audience was large and, presumably, diverse and relatively few of them would have had a college education. Judging from a graph in Caplow, Hicks, and Wattenberg, The First Measured Century (p. 53) fewer than 10% of adults had a college degree and only about 25% had graduated high school.
I, of course, though “Freud and psychoanalysis” when I heard that term, especially in that context. But the Freudian term is “unconscious” rather than “subconscious”, and, as the Wikipedia entry for “subconscious” points out, Freud explicitly rejected the term. Rather, “subconscious” is a lay term that sometimes erroneously substitutes for “unconscious” and sometimes means, well, the subconscious mind.
Which came in vogue early in the last century. I queried Google’s Ngram Viewer on “subconscious” and “unconscious” and discovered a thing or two. First, “unconscious” appears far more often than “subconscious”, with peaks just after 1920 and in the mid-1950s. Given that the Ngram Viewer is running against a database of books rather than of print in general that seems to make sense. But it would be interesting to run the query against popular periodicals and popular books. Second, “subconscious” peaks just after 1920, but then falls, never to rise again (this is clearer in this query on “subconscious” only).
A bit more sleuthing turned up this ad from Popular Science in March of 1923 touting Self Mastery Through Conscious Autosuggestion by one Emile Coué, who
stands out today as the man who has discovered just what to do to put in operation the great forces in our subconscious mind to help us achieve whatever we desire.
I’ve not read the book and what little I’ve read about it suggests that it’s not going to say anything about mental mice giving you inspiration while asleep. But it does have the feel of the kind of pop psych that was likely rather well known. Further, Coué’s ideas were picked up by Norman Vincent Peale and Robert Schuller, which seems to be the right popular ball park.
So I’m guessing that Coué and similar writers are more responsible for the early 1920s peak of “subconscious” than Freud is and that this strain of thinking is more likely to have been known to Disney’s 1940s audience than psychoanalysis is.