To speak about representation in psychology with reference to psychophysics might appear somewhat paradoxical. If by "representation' is meant (in a broad sense) a mental construct in the absence of (or at least independent from) actual sensory stimulation, then psychophysics is paradigmatically the exact contrary of the psychology of representation. In a certain sense, psychophysics is the branch of psychology which studies the relation between stimulation and sensation, and does so relatively regardless of mental contents. I believe that this image is only partly true, or least it is only adequate. In order to gain thorough understanding of the historical evolution of the concept of representation in psychology, careful examination of some aspects of psychophysics is recommended.