Not a study, but...in Ron Chernow's bio of Alexander Hamilton there are a couple of places where he mentions that AH was notable for talking to himself while wa

Not a study, but...in Ron Chernow's bio of Alexander Hamilton there are a couple of places where he mentions that AH was notable for talking to himself while walking from place to place. [1] Your comment made me think of it because his tremendous impact and voluminous output made that behavior seem odd. But, perhapse they where related. [1] https://books.google.com/books?id=4z5eL5SGjEoC&pg=PT438&lpg=PT438&dq=ron+chernow+hamilton+walks+and+talks+to+himself&source=bl&ots=utaBEorpMe&sig=vCUgePPmYS1xq-0lyey2JhZFlWo&hl=en&sa=X&ved=0ahUKEwiclbeh6fzXAhUKSiYKHconD74Q6AEIUzAO#v=onepage&q=ron%20chernow%20hamilton%20walks%20and%20talks%20to%20himself&f=false https://books.google.com/books?id=4z5eL5SGjEoC&pg=PT438&lpg=...