During the war he was a corporal in the Army Air Forces as an assistant personnel consultant in psychological testing. At Princeton he was in the band, the orchestra, and the Triangle Club band, and was a member of Court Club. He graduated summa cum laude in psychology.

He married Carolyn Godfrey Hall and earned a Ph.D. in psychology from Stanford University. They were married for 41 years and had three children. He later married Irene Sutherland, to whom he was married for 31 years.

John retired as a senior scientist from Litton Data Systems, where he had spent much of his career. His job sent him to many of the world’s major cities on six of the seven continents, missing only Antarctica.

He was active in many community theater productions as both an actor and director. He directed Bryan Cranston in Bell, Book, and Candle.

John was predeceased by his wives and a son, John H.K. Schwarz. He is survived by daughter Nancy H. Roche, son Philip, two grandchildren, and four great-grandchildren.