Douglas T. Kenrick in Psychology Today:
Here’s a one-item test: “Who founded the science of psychology?”
One possible answer would be “William James,” who wrote the first psychology textbook, Principles of Psychology, in 1890.
You would get a few more points for answering “Wilhelm Wundt.” Indeed, Wundt started the first formal laboratory in 1879, at the University of Leipzig, and William James was initially inspired to study psychology when he read one of Wundt’s papers in 1868, whilst visiting Germany.
But Wundt himself had started his career as a lab assistant to the man I would nominate as psychology’s first true genius: Hermann Helmholtz.
Helmholtz made at least two great contributions to modern psychology…
More here.