Four experiments are described in which the threshold of fusion of paired flashes was measured. The intensity of the single flashes making up the pairs was varied independently. The results showed that when the first flash of the pair was the more intense, the threshold of fusion increased linearly as the difference in the log intensity of the two flashes. A proposal put forward to explain the results suggested the “noise” created by the first flash of the pair has to dissipate to a critical extent to allow the “signal” arising from the second flash to be detected.
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References
1.
BakerH. D. (1963). Initial stages of dark and light adaptation. J. opt. Soc. Amer.53, 98–103.
2.
BartleyS. H. (1939). Some factors in brightness discrimination. Psychol. Rev.46, 337–58.
3.
CrawfordB. H. (1947). Visual adaptation in relation to brief conditioning stimuli. Proc. Roy. Soc. B.134, 283–302.
4.
DonchinE.LindsleyD. B. (1965a). Visually evoked response correlates of perceptual masking and enhancement. EEG clin. Neurophysiol19, 325–335.
5.
DonchinE.LindsleyD. B. (1965b). Retroactive brightness enhancement with brief paired flashes of light. Vision Research5, 59–70.
6.
DonchinE.WickeJ. D.LindsleyD. B. (1963). Cortical evoked potentials and perception of paired flashes. Science141, 1285–6.
7.
EvartsE. V. (1960). Effects of sleep and waking on spontaneous and evoked discharge of single units in visual cortex. Fed. Proc.19, 828–37.
8.
HornG.VenablesP. H. (1964). The effect of somaesthetic and acoustic stimuli on the threshold of fusion of paired light flashes in human subjects. Quart. J. exp. Psychol.16, 289–96.
9.
KietzmanM. L.SuttonS. (1968). The interpretation of two-pulse measures of temporal resolution in vision. Vision Research in press.
10.
KopellB. S.NobleE. P.SilvermanJ. (1965). The effect of thiamylal and methamphetamine on the two flash threshold. Life Sci.4, 2211–4.
11.
LindsleyD. B. (1957). The reticular system and perceptual discrimination. Reticular Formation in the BrainJasperH. H.London: Churchill.
12.
MahnekeA. (1958). Foveal discrimination measured by two successive light flashes. Acta Opthalmologica36, 3–11.
13.
RaabD. H. (1963). Backward masking. Psychol. Bull.60, 118–29.
14.
VaughanH. G.CostaL. D. (1964). Application of evoked potential techniques to behavioural investigation. Ann. N.Y. Acad. Sci.118, 71–75.
15.
VenablesP. H. (1963). The relationship between level of skin potential and fusion of paired light flashes in schizophrenic and normal subjects. J. Psychiat. Res.1, 279–87.
16.
VenablesP. H. (1967). The relation of two flash and two click thresholds to withdrawal in paranoid and non-paranoid schizophrenics. Brit. J. soc. clin. Psychol.6, 60–2.
17.
WinerB. J. (1962). Statistical Principles in Experimental DesignNew York: McGraw-Hill.
