Page:Mind (New Series) Volume 12.djvu/578

564 PHILOSOPHICAL PERIODICALS. character of our space formations.] E. Wiersma. ' Untersuchungen iiber die sogenannten Aufmerksamkeitsschwankungen.' in. [Experi- ments on normal fluctuations of attention, and on fluctuations during induced abnormal states of consciousness, have pointed to a central origin of the changes in perception. The present paper seeks to confirm these two arguments by experiments upon the insane. Seven cases are reported. "The capacity of perception is influenced by mental de- rangements of various kinds. Depressive derangements clearly exert an inhibitive influence; nothing definite can be said of the effects of exaltation." An account of experiments on epileptics is promised for the near future.] H. Feilchenfeld. ' Zur Lageschatzung bei seitlichen Kopfneigungen.' [If the head is inclined towards the shoulder, a vertical light line in a dark field is (apparently) inclined in the opposite direction (Aubert's phenomenon). The phenomenon is almost mathe- matically constant ; but there are fluctuations, uncertainties, which do not affect the final result, but nevertheless call for explanation. When double vision occurs, it is to be subsumed to an extension of Bering's law that the space of binocular regard is smaller than the portion of the space of regard common to both eyes : the extension runs, " The space of binocular regard is also smaller with inclined head than it is with head upright ". The explanation is to be found in the unusual nature of the required innervations ; the synergic movements necessary for binocular single vision have not been practised. The general phenomenon cannot be referred to compensatory torsion, to underestimation of the inclina- tion of the head (Helmholtz), or to forgetfulness of the inclination (Aubert). Knowledge of the position of head and eyes is just as complete or incomplete as it normally is ; what the phenomenon shows is the inadequacy of this knowledge as the sole condition of localisation. Here, then, is the key to the paradoxical constancy and inconstancy of the illusion. The reason that the illusion appears only in the dark is given by genetic (empirical) considerations. "Die Umwertung ist unter dem Einflusse der Erfahrungsmotive entstanden, hat sich aber im allge- meinen von demselben freigemacht." Experiments in which empirical motives are ruled out, and the movements of the object correspond to those of the head (i.e., in which the compensatory eye-movement of rotation about the frontal and vertical axes is rendered superfluous), give no illusion during the movement of inclination towards the shoulder. Criticisms of Sachs' nativistic view of the Umwertung : " sie hat bei ihm nicht mehr den labilen Charakter einer werdenden oder gewordenen Einrichtung, sendern den eines pracise funktionierenden Mechanismus." Test experiments upon deaf mutes prove the incompleteness of the Umwertung.] Literaturbericht. PHILOSOPHISCHE STUDIEN. Bd. xviii., Heft 4. D. Awramoff. ' Arbeit und Rhythmus.' [A study of the influence of rhythm upon three modes of work : lifting weights, reacting to stimulus by lifting weights, and writing. The results are given in great detail, and we can here quote only a few of the more important. (1) Lifting weights : quantity of work. Every observer has his own rate of work, which however varies within certain limits. At this rate, less work is done, but it is done with pleasure ; with prescribed rates, more work is done, with greater output of energy. The quicker the prescribed rate, the greater the increase in quantity of work ; but the accompanying feeling changes from pleasant to unpleasant, and then to positively painful. There is a special rate for the lifting of a given weight. The height of lift is more regular with a natural than with pre- scribed rates. (2) Lifting weights : quality. Every observer works most effectively at his own rate. The positive effect of rhythm upon conscious-