The history of I/O psychology can arguably be said to have originated in the late 19th century. During this time, psychologists were interested in studying and measuring human capabilities and motives. Walter Dill Scott wrote a book, The Theory of Advertising (1903), which is considered to be the first book amalgamating psychology and commerce. This book was succeeded by The Psychology of Advertising (1908). Hugo Munsterberg a psychologist teaching at Harvard also published a book called, The Psychology of Industrial Efficiency (1913). Muinsterberg was highly interested instudying human efficiency and its applications in production.

During the time the US participated in World War I psychologists began to investigate soldier morale, motivation, and psychological impairment. It was also during this time that the US Army hired psychologists to develop a testing method to identify soldiers for certain duties, thus, the birth of a group-administered intelligence test called the Army Alpha. While , little use was made of the results at the time since the war ended a mere three months after the testing program was authorized. However, research studies did show that the test scores were related to soldier performance.

After the war, in 1919, the first university-based center for studying the applications of psychology to business was established at the Carnegie Institute of Technology. Called the U.S. Bureau of Salesmanship Research,

The single most significant event which heralded the age of I/O psychology, to me, would be when the US Army hired psychologists to develop a method of identifying soldiers for the right positions and duties. About 1,726,000 enlisted men and officers were tested and although the results werent used at the time the data showed empirical evidence correlating intelligence with productivity and performance, which today helps companies select the right person for the right job, placing a square peg in a square hole so to speak.

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