EFFECT OF A CHANGE IN THE DISTANCE BETWEEN TWO SEPARATE RETINAL AREAS UNDER STIMULATION ON THE FORM OF “SIMULTANEITY SURFACE”

Abstract

The author intended in this research to investigate how a change in the distance between two retinal areas stimulated in monocular vision affects the simultaneity surface. The subjects for the experiment were three healthy young adult persons.
The following is the resume of the experimental results.
1) When two areas to be stimulated are so arranged as to be in contact with each other the simultaneity-probability exceeds 70 per cent but failes to reach 100 per cent in the constant probability duration. It ranges between 50-60 per cent, when the distance between stimuli is 5.0 or 10.0 mm. in distinct vision.
2) The constant probability duration is shorter when the distance is zero than when it is 5.0 and 10.0 mm. The length of constant probability duration is 3.6 to 4.4 msec. when the distance is zero and 4.6 to 6.0 msec. when it is 5.0 mm.
3) The probability of judgement on the successiveness of sensations reaches almost 100 per cent and the rate of correct judgement on the sequence of stimuli rises over 90 per cent when two stimuli set in contact are given at the intervals of 8.2 msec., and they are always in lower percentage when the stimuli set 5.0 or 10.0 mm. apart are given at the same intervals. The simultaneityprobability curve for the zero stimuli distance, therefore, intersects that for astimuli distance of 5.0 or 10.0 mm. in the neighborhood of the interval of 3.3 msec.
4) The simultaneity-probability in the constant probability duration in case of the stimulation of the retina by a red or green light is somewhat lower than that traced when the stimulus is white light.