What are the basic data of psychology? In the early years of experimental psychology, they were reports of ''brighter'' or "heavier" or other esti- mates of the magnitude of differences between the sensory stimuli pre- sented in psychophysical experiments. Introspective accounts of the ex- perience of seeing colored lights or shapes were important sources of psychological data in the laboratories of Cornell, Harvard, Leipzig, or Wiirzburg around the...