Seashore was born in Mörlunda,
Hultsfred Municipality,
Kalmar County,
Sweden, to Carl Gustav and Emily Sjöstrand. He emigrated with his family to the United States in 1870 at the age of 3 due to both economic and religious considerations and settled in
Rockford, Iowa, before moving and settling in a farming community located in
Boone County, Iowa. The name "Seashore" is a translation of the Swedish surname Sjöstrand. Seashore had two sisters and two brothers who were all educated in Swedish. His father, Carl Gustav Seashore, was a lay preacher and built a church, where Seashore began serving as the church organist at the age of 14. He graduated from
Gustavus Adolphus College in
St. Peter, Minnesota, in 1891, having studied mathematics, music, classical languages and literature. Music was considered the "most important extracurricular activity in college" and he enjoyed singing at all sorts of collegiate occasions. During his years in college he served as the organist and choir director of a local
Swedish-American Lutheran church and his salary there paid most of his college expenses. Seashore became a member of the Iowa Beta chapter of
Sigma Alpha Epsilon. Seashore attended
Yale University when it had just opened the Graduate Department of Philosophy and Psychology. He studied under
George Trumbull Ladd, professor of
metaphysics and
moral philosophy, and
Edward Wheeler Scripture, an experimental psychologist who conducted research on phonetics. In 1877, Ladd had authored the standard American textbook
Elements of Physiological Psychology. In 1895, Seashore was awarded the school's first
Ph. D in psychology for his dissertation on the role of inhibition in learning.{{cite web After receiving his Ph.D. degree from Yale, Seashore spent the summer in Europe to visit different German and French psychology laboratories before returning to
Yale University as a Fellow in Psychology and an assistant to Ladd. In 1897, he was offered a permanent position at Yale. Additionally, he was also offered an opportunity to go to
China as a missionary teacher. However, he decided to return to his home state and spent the next fifty years as a researcher and an assistant professor of psychology at the
University of Iowa. In 1908, Seashore was made Dean of the Graduate School at University of Iowa, where he maintained the position for nearly 30 years. He became president of the
American Psychological Association in 1911 and presided over the 20th meeting in Washington, D.C. ==Career==