Page:Mind (New Series) Volume 12.djvu/444

 430 PHILOSOPHICAL PERIODICALS. earlier investigators. On the other hand, the results of Angell and Pierce, whose complication apparatus gave the visual series with con- stant rapidity, are discrepant. Moreover, there is no sort of unity in the matter of psychological explanation. (1) New experiments were under- taken with a complication clock, i.e., an instrument whose hand moved at constant rapidity, and not with the acceleration of the pendulum-hand. The first question was, to decide between the positions of the Leipzig workers and of Angell and Pierce : the former found an influence of rapidity, but none of practice ; the latter, a marked influence of practice, but none of rapidity. The new experiments show that, under the revised conditions, both factors are at work : increasing practice and increasing rapidity induce a positive tendency to temporal displacement (Wundt's terminology), decreasing rapidity a tendency to negative displacement. But further : the observers fall into two types, a naive type, who await the course of events, and let the apparatus (so to speak) decide for them the point of coincidence, and a reflective type, who actively exert them- selves to discover the right scale-mark. The former may be called the ' hand,' the latter the ' scale ' observers : the former also are objective, the latter subjective. T3'pe affects both size and kind of error. Both types show the effect of practice : only the naive that of rapidity, at least with any clearness. The naive observers give negative, the reflective predominantly positive displacement*. Other factors at work in the total result are individual differences, accidental changes of disposition from day to day, differences in the length of the scale-marks on the clock-face, and the spacial position (above, below, etc.) of the mark at which the bell sounds. (2) The author now gives a detailed criticism of the theories of von Tschisch, James, Pierce and Angell, and Ebbinghaus. He finds the key to the gross phenomena in the adaptation of attention to the series of impressions (Wundt's Spannunggwactuthum V/- A n.fm erksamkeit). The explanation is fully worked out : it cannot well be summarised here. Accidental predirectioris of attention also play their part, as does a diver- sion of preadjusted attention by the prominence of certain ideas within a mental whole. The error of position is accounted for by the relative ease of downward movement of the eyes, by the after-effect of previous experiences of movement, and by the prominence given to the upper and lower ends of the vertical diameter as points of reversal of movement.] P. Bader. ' Das Verhaltniss der Hautenipfindungen und ihrer nervosen Organe zu calorischen, mechanischen und faradischen Reizen.' [A study undertaken with the view of comparing the sensations aroused by the same stimulus at different points upon the skin. In general, the existence of cold; warm, pain, pressure, and anaesthetic and analgesic spots is confirmed. (1) Cold spots. The three intensities, cool, cold, icy ; detailed account of the perceptions set up by application of temperature stimuli to cold spots (report of seven expts.) ; the limen of the para- doxical cold sensation (the sensation occurred with stimuli under 31 C. ; a lower limen exists only in the sense that there is a limit at which all or nearly all of the cold spots reply to stimulation, while below it they fail to respond ; the constant characteristic of the sensation is its discon- tinuous course) ; cold sensations are easily aroused, in most cases, by mechanical stimulation of the spots (four expts.) ; not all spots respond to faradisation, and the sensation is discontinuous ; it is probable that the arousal of a paradoxical cold sensation involves stimulation of the end-organ, the neighbouring nervous organs, and their corresponding nerve-fibres. (2) Wurnt xjiofs. Characterisation of the sensation ; the degrees of warm and hot. Heat is not a mixed excitation of warm and cold, as Alrutz declares. The warm spots do not respond freely to