This study investigates the effect upon threshold of multiple light pulses, 0.01 second in duration, that fall on the peripheral retina. In one series of experiments a train of 1 to 5 such pulses is presented, the interval between pulses being 0.01 second. The maximum duration of such a train of pulses is shorter than the critical duration for a single flash of light, found by Long to be 0.10 second, under conditions similar to those that hold in the present investigation. In another series of experiments, threshold determinations are made for two such pulses separated by 4 temporal intervals less than, and by 6 temporal intervals greater than, critical duration.
The results indicate that the breaking up of a light stimulus into separate flashes has no effect upon threshold provided these flashes occur within a critical duration. When 2 flashes are separated by temporal intervals greater than critical duration, threshold energy rises and, at a temporal separation of 0.5 second, is the same for each of two flashes as it is for one flash. Under the latter circumstances the subject reports the existence of two flashes.
© 1952 Optical Society of AmericaFull Article | PDF Article
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