Behavioural assessment of flicker
fusion frequency in chicken Galius gallus domesticus.
Assessment of Psychomotor function by critical flicker
fusion frequency: Correlation with age.
Because
fusion frequency is also correlated with latitude, southern populations would be expected to have a bigger size than northern ones.
At the second stage ophthalmological status (acuity of vision and refraction) was estimated as well as functional (critical flicker
fusion frequency -CFFF) electrophysiological (electrosensitivity threshold -EST; electrolabilityEL), phychophysiological (channel capacity- CC, visual information volume -VIV, visual information speed -VIS, efficiency of visual information analysis -EVIA) investigations were carried out [4, 5].
where [fusion.sub.n] is nth fusion value, real is real value, and N is
fusion frequency.
Most humans are unable to perceive flicker in light above 60 Hz, but there still remain measurable biological effects above the critical
fusion frequency. ERG (electroretinogram) responses indicate that invisible flicker is transmitted through the retina, even up to 200 Hz (Berman,1991).
To address this issue, electro-retinography was used to measure the changes in retinal light sensitivity, flicker
fusion frequency, and spectral sensitivity in black rockfish (Sebastes melanops) subjected to rapid decompression (from 4 atmospheres absolute [ATA] to 1 ATA) and Pacific halibut (Hippoglossus stenolepis) exposed to 15 minutes of simulated sunlight.
Flicker
fusion frequency experiments involved presenting the eye with square pulses from a flickering stimulus light, generated by cycling a computer-controlled electromagnetic shutter in the light path, for 2 s at a given frequency with a 50:50 light/dark ratio, and recording the corresponding ERG (see Frank, 1999).
When measured by means of the flicker
fusion frequency (FFF), this effect is present only when normal eye movements are permitted.
However, Moeller and Case (1995) measured the critical flicker
fusion frequency at threshold light intensities, which is difficult to compare between species because (1) the threshold sensitivity of a crustacean eye measured using the ERG technique varies considerably from preparation to preparation (pers.
The flicker
fusion frequency was measured with 10 ms flashes in dark adapted crabs, as well as in crabs adapted to and tested in 11.65 [[micro]watts]/[cm.sup.2] fluorescent light.