In the classic frequency-of-seeing experiment with a small brief stimulus, the overall efficiency F is 0.06 (λ = 507 nm) in conventional long experiments and 0.09 in pooled short experiments. These results can be reconciled by postulating higher-level effects in the long experiments, which increase variability without substantially changing mean threshold. The quantum efficiency of dark-adapted vision Fd, the fraction of corneal photons acting at the decision level, is estimated to be 0.13–0.20 (maximum range, 0.12–0.30).
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Stimulus conditions: test of 8–40-arcmin subtense, 1–25-msec duration, 495–530-nm λmax, 18–20-deg retinal eccentricity, monocular viewing, and central or peripheral pupillary entry.
Revised data from Ref. 8.
The stimulus was blue–green (507-nm peak), 22 arcmin in subtense, 10 msec in duration, and at 18 deg of temporal retinal eccentricity. The conditions were those of dark-adapted monocular viewing with central pupillary entry and no background. The background for the noise sample was at λmax = 510 nm. Subjects were 19–23 years old. Other details are described in Ref. 8.
Fifty flashes were used at each intensity.
Five flashes were used at each intensity.
The noise underestimate is defined as Xατ photons (507 nm at the cornea).
Stimulus conditions: test of 8–40-arcmin subtense, 1–25-msec duration, 495–530-nm λmax, 18–20-deg retinal eccentricity, monocular viewing, and central or peripheral pupillary entry.
Revised data from Ref. 8.
The stimulus was blue–green (507-nm peak), 22 arcmin in subtense, 10 msec in duration, and at 18 deg of temporal retinal eccentricity. The conditions were those of dark-adapted monocular viewing with central pupillary entry and no background. The background for the noise sample was at λmax = 510 nm. Subjects were 19–23 years old. Other details are described in Ref. 8.
Fifty flashes were used at each intensity.
Five flashes were used at each intensity.
The noise underestimate is defined as Xατ photons (507 nm at the cornea).