Reference Work Entry

Encyclopedia of Psychopharmacology

pp 361-362

Critical Flicker Fusion Frequency

  • Hamish McAllister-WilliamsAffiliated withSection Behavioural Pharmacology, Institute of Psychiatry, King's College LondonPsychiatry, Newcastle University, Royal Victoria Infirmary


CFFF; Flicker fusion rate; Flicker fusion threshold


Critical flicker fusion frequency (CFFF) is the frequency at which an intermittent light stimulus appears to be completely steady to the observer. This is often measured by exposing the subjects both to a low-frequency flicker, by increasing the frequency to the point the subject has the sensation that the flickering stops, and a high-frequency flicker that decreases to the point where the flicker is detected. The CFFF is the mean of the two. If the frequency at which frames are displayed in a film falls below the CFFF then the image will be perceived as jerky.

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