Although there are many investigations of the problem of visual apparent motion which occurs under the condition of the so-called stroboscopic exposure, we have not yet any knowledge about what phenomena occur when two tonal stimuli which differ in vibration frequency or, in other words, in their pitch are given alternately in succession, that is, under the stimilar condition to stroboscope exposure. This study is intended to contributa to this problem.
The arrangement employed for this purpose consists of an ellectric tube oscillator and four adding condensers and one or two rotating contact for opening and shutting the circuit of added condenser. (See Fig. in the Japanese text). Bythis arrangement we can get successive series of two tones, thus ababa b
The following is the summary of results obtained from observation of six subjects when the stimulus distance of the successive tones do not exceed major second in the region of about 512 d. v.
(1) We have the impression that the higher tone a moves continuously downward to b (high-low. group) s or the lower tone b moves upward. to. a (low-high group), without any phenomenal gap in each case. This impression, which corresponds to optimal stadium, occurs when the distance between the two stimuli or vibration difference of the two is still small.
(2) We have also those corresponding to the g-stadium and the stadium of partial movement.
(3) This impression that “tone moves” is not resulted from association, but directly given there and is compelling.
(4) By inspecting photographic records taken by the aid of oscillograph we reach the conclusion that these phenomena of motionality are so-called apparent and storobscopic, as the records show that the alternation of the stimuli is done abruptly without any real gliding-down of Vibration rate anywhere.
(5) The impression of melodiousness appearssometimes in the motional phenomenon itself, but the former does not get spoiled so easily as the latter when the stimulus distance becomes wider. This fact suggests that the opinion of Hornbostel and Watt that melody is motion itself in psychological nature is not acceptable.
(6) Also from the constellation in which objective pause p is inserted between the two stimuli a and h, namely, in the form a p b or a h p , we can get good motional phenomena although somewhat poorer in character than those from a b constellation.
(7) Factors influenceable upon these phenomena are these:
(a) Stimulus distance or vibration difference of the two tones a and b, in such a way that the larger the distance, the poorer, the motionality, and the smaller the former,the richer and fuller the latter.
(b) Duration of each stimulus or the rate of succession, in such a way that shorter the duration, the fuller and richer the motionality, and the longer the former, the poorer the latter .
(c) Inner factors on the observer's side, for instance, subjective grouping of tones, attitude, etc; of which the former is the most important one. (See the Janpanese text)
(d) Frequency of observation.
(8) Stimulus intensity affects motionality neither qualitatively nor quantitatively.
(9) Courses of effects of the first two factors (See (7) (a) and (b) above mentioned) and the ineffectiveness of intensity factor suggests invalidity of Korte's law in this field.
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