Hugo Münsterberg (/ˈmʊnstərbɜːrɡ/; June 1, 1863 – December 16, 1916) was a German-American psychologist. He was one of the pioneers in applied psychology, extending his research and theories to industrial/organizational (I/O), legal, medical, clinical, educational and business settings. Münsterberg encountered immense turmoil with the outbreak of the First World War. Torn between his loyalty to the United States and his homeland, he often defended Germany's actions, attracting highly contrasting reactions.