 Nevertheless, Wundt repeatedly addresses the objections raised against the very possibility of psychological, as opposed to physiological or psychophysical, experimentation. How are we to subject the mind-body complex to physiological stimulation such that the reactions may be given a purely psychological interpretation? From the physiological point of view, experimentation with stimulus and response are not experiments of sensation, but of externally observable excitations and reactions of nerve and muscle tissue. For example, a nerve fiber or a skin surface may be given an electric shock or brought into contact with acid, and twitches of muscle fiber are observed to follow. It is obvious, especially when the nerve-tissue in question belongs to a dead frog (Wundt describes such an experiment in PP), that these experiments say nothing about the “inner” experience or consciousness of sensation. Wundt’s innovation is the attempt to project the experimental rigor of physiology into the domain of inner experience by supplementing these experiments with a purely psychological set of procedures. These procedures constitute Wundt’s well-known yet misunderstood method of Selbstbeobachtung, i.e. “introspection” or, better, “self-observation”.