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The flicker of a CRT monitor can cause various symptoms in those sensitive to it such as eye strain, headaches [9] in migraine sufferers, and seizures in epileptics. [10]As the flicker is most clearly seen at the edge of our vision there is no obvious risk in using a CRT, but prolonged use can cause a sort of retinal shock where the flickering is seen even when looking away from the monitor.
Temporal light artefacts (TLAs) are undesired effects in the visual perception of a human observer induced by temporal light modulations. Two well-known examples of such unwanted effects are flicker and stroboscopic effect. Flicker is a directly visible light modulation at relatively low frequencies (< 80 Hz) and small intensity modulation levels.
In visual perception, flicker is a human-visible change in luminance of an illuminated surface or light source which can be due to fluctuations of the light source itself, or due to external causes such as due to rapid fluctuations in the voltage of the power supply (power-line flicker) or incompatibility with an external dimmer.
Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz (twice of the utility frequency; the lamp is lit on both the positive and negative half-wave of a cycle). This flickering can cause problems for some individuals with light sensitivity [1] and are
When the screen was to be redrawn, the cursor would be moved and games had an opportunity to update the display. It could sometimes be difficult to avoid a race condition between a game and the raster display. Flicker could result from the processor writing to the image while it was being sent to the CRT.
However, a faulty fluorescent lamp can flicker at a much lower rate and trigger seizures. [medical citation needed] Newer high-efficiency compact fluorescent lamps (CFL) with electronic ballast circuits operate at much higher frequencies (10–20 kHz) not normally perceivable by the human eye, though defective lights can still cause problems.
These were addicts who wanted to stop using, or at least heard the message. They went to abstinence-based, military-themed rehabs and out-of-state Bible-themed rehabs. Some had led meetings or proselytized to addicts in church groups on the power of 12-step. They participated in 12-step study nights. One lived with his NA sponsor.
The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science , more specifically in the psychophysics of visual perception .