Unconscious inferences in perception in early experimental psychology: From Wundt to Peirce.

What are unconscious inferences in psychology? This article investigates their journey from the early philosophical psychology of Wilhelm Wundt (1832-1920) to the experimental psychology of the American pragmatist Charles S. Peirce (1839-1914). Peirce's reception of Wundt's early works situates him in an international web of 19th-century experimental psychologists and its reconstruction opens new perspectives on the relation between philosophy, psychology, and epistemology. Moreover, this reception testifies to a heretofore overlooked strand of influence of Wundt on North American experimental psychology. The notion of unconscious inferences, of which Hermann von Helmholtz is usually considered the chief exponent, becomes the backbone of Peirce's theory of perception mostly because of the affinity between Wundt's early philosophy of mind and Peirce's logic-mediated approach to psychology.