William T. Preyer

Born in Manchester on July 15, 1841, and educated in Germany, William Thierry Preyer became a physician, physiologist, and psychologist best known for bringing careful scientific observation to the study of infancy. He taught at the University of Jena and worked across several fields, including physiology, anthropology, hypnosis, and child development.

Preyer is especially remembered for The Mind of the Child, a landmark study based on detailed observations of his own son from birth. By recording when abilities such as seeing, hearing, movement, memory, and speech began to appear, he helped establish child psychology as a serious area of research rather than a matter of guesswork.

His wider body of work was equally varied, with writings on topics such as hemoglobin, embryology, sleep, and evolution. He died in Wiesbaden on July 15, 1897, but his careful, evidence-based approach continued to influence both developmental psychology and the scientific study of human behavior.