With relation to the content of consciousness present in the various reactions employed Ach expressly states or implies the following observations:
(1) The particular content of consciousness present in a given reaction varies, first with the individual tendencies. ("Individuelle Veranlagung spielt hier eine grosse Rolle.") It varies also with practice and, thirdly, with the apperception of the stimulus.
(2) The mental processes involved in all voluntary action are in no small degree determined by what the author calls "determining tendencies." These tendencies are the results of the presence of an idea of a goal or end to be accomplished by the reaction. In themselves these tendencies may be entirely unconscious, but they are nevertheless essentially effective in shaping the mental content controlling the reaction.
(3) When the reaction itself takes place there is no discoverable "will" process or content, as such, present. All this comes at an earlier period when the subject consents, as it were, to the procedure as a whole.
(4) Ach and his subjects discover in the content of the volitional consciousness what may be classed as two sorts of sensation, both, however, being necessarily present only in the early and unlearned stages of the reaction. Both may be entirely absent at the later and familiar stages. The first sort of these sense processes is made up of the usual peripheral sensations set up by the stimulus. The other class, highly important in Ach's aceount, is essentially kinæsthetic sensations. Ach prefers to call them "intentionalen Bewegungsempfindungen." They are, however, he tells us, "Spannungsempfindungen" and have their origin in the muscles. Their function is to give us the trend or direction ("Richtung") of the forthcoming movement. Ach speaks also of sensations which are mere accompaniments—Begleiterscheinungen—which do not appear to serve any particular function.
(4) Then there are all sorts of memory images, visual, acoustic, kinæsthetic, etc., which present themselves most frequently in the early stages of voluntary action and then disappear more or less. Upon the presence of these images, which constitute the essential elements in the image theory, Ach does not appear to lay much stress.
(5) Finally there is present, particularly after practice and frequently in the period after the ready signal has been given (Vorperiode), a functional mental content—and sometimes it constitutes the entire consciousness of the moment—in which no imagery at all is to be found. This consciousness is at times entirely without sensations of any kind; even the highly important "intentionalen Bewegungsempfindungen" are wanting.
