Miller taught the course "Introduction to Psychology" at Alabama for two years. He enrolled in the Ph.D. program in psychology at Harvard University in 1943, after coming to the university in 1942. At Harvard he worked in Psycho-Acoustic Laboratory, under the supervision of Stanley Smith Stevens, researching military voice communications for the Army Signal Corps during World War II. He received his doctorate in 1946; his doctoral thesis, "The Optimal Design of Jamming Signals," was classified top secret by the US Army.