Abstract: The frequency discrimination thresholds of simultaneous flash signals composed of alternative bright and dim phases were measured under laboratory conditions. When the frequency of flash signals falls within the range of 40 c/min to 220 c/min the discrimination threshold follows Weber's law, expressed by the equation △f=0.17f+9.95. Five frequencies with discrimination accuracy above 95% were determined. They are: 44.2/110.8, 60.0/150.3, 81.5/204.7, 110.8/277.8, 150.5/377.2 (unit: c/min).

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