Logically considered simultaneous point of time has no duration, just as a geometrical point is considered as having no duration. Has the phenomenal simultaneity, immediately given in experience, also no duration?
The experiment was performed in a dark room. In our first series of the experiment, a vertical line of light-stimulus (objectively 1 mm wide) was made to move from the left to the right in the field of two rectangular holes (each 60-25 mm in size), the upper one of which was fixed while the lower one (10 mm apart from the upper) was made slidable either to the left or to the right, the distance between the left-edge-position of the lower and the right-edge-position of the upper being measured. Thus, two moving lines of light-stimulus, each 25-1 mm in size, appeared successively. The phenomenal time and space relations between the disappearance of the upper line and the appearance of the lower one were recorded always with regard to the lower.
Results: (1) The phenomenal simultaneity did not always go together with the physical one, and even went inversely sometimes. The phenomenal simultaneity was experienced when there was objectively succession between the disappearance and the appearance. This range of succession we called “the simultaneous region”
(2) The simultaneous region was large (sometimes over ± 100°) or small according to the velocity of the physical movement of the stimulus-line; and with certain high velocity only one simultaneous point was got or none at all, while another sort of simultaneous region was gained, where two still-standing light-rectangles were simultaneously seen. This sort of simultaneity we called the experience of “simultaneous existence.”
(3) The range of the simultaneous region was, in some degree, of in-dividual difference: by 3 cm/sec, for instance, the first type of the distribution extended from about 100° before (-100°) to about 100° after (+100°), the second type, approximately from 100° to 15°, and the last type, from-30° to +100°. Usually, however, the distribution moved toward the “objectively-after” (+) according as the velocity was increased.
Some conditions which had some effect upon the phenomena were looked for in the following series of experirnent.
(A) The two reetnngular holes were so fixed as the left educ of the lower hole always being kept vertically under the right edge of the upper. The two vertical lines of light-stimulus, variously apart from each other, appeared successively-the upper line only in the upper hole and the lower line in the lower hole.
(B) Shortening of the routes (each 60 mm) of the movement, a) by halves (30 mm) b) by 59 mm (1 mm).
(C) Colouring of the two lines. a) red b) greenish-blue.
(D) Reducing of the objective width of the stimuli (0.3 mm).
(E) No fixing of the eyes on the fixation-point.
(F) Transposing of the two holes with one another.
Results: (4) The simultaneous region was wide or narrow according to the width of the light-stimuli.
(5) Shortening of the route of the movement made the simultaneous region draw nearer to the “objectively-after”, and without any longer route than the width of the stimulus itself, “simultaneous existence” was experienced, the region of which extended symmetrically to “the objectively-before” and “the objectively-after.”
(6) Colouring of the stimuli made the simultaneous region more or less small.
(7) Without fixing of the eyes on the fixation-point, the simultaneous region moved toward “the objectively-before.”
(8) Different mental attitudes varied the phenomenal simultaneity in high degree.
Further investigations are required.
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