Temporal vision
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This document discusses properties of flicker perception and critical flicker frequency (CFF). It defines CFF as the temporal frequency at which a flickering stimulus is perceived as non-flickering. It notes that CFF increases with retinal illumination per the Ferry-Porter law and that stimuli between 50-100 ms appear brighter than shorter or longer stimuli per the Broca-Sultzer effect. Examples of different types of masking phenomena are also provided.
Temporal vision
- 2. Frequency= Cycles/second = Hertz
- 4. Relative SensitivityLow modulation ïƒ steady (non-flickering) stimulusHigh modulationïƒ flickering stimulusRelative Sensitivity = 1/ (% Modulation)As the % modulation increases , the relative sensitivity decreases
- 7. Critical Flicker FrequencyFor a specific % modulation, temporal frequency is increased until the stimulus does not flicker (fuses)This is called CFF = Critical Flicker Frequency
- 10. LowHigh No flickerNo flickerFlicker
- 11. Loss at low frequenciesTroxler phenomenonPurkinje tree visualization
- 15. Loss at high frequencies
- 16. Ferry-Porter law: CFF increase with log of retinal illumination
- 17. Broca-Sultzer effectStimuli with duration between 50 and 100 ms are perceived brighter than shorter or longer stimuli
- 18. Brucke-Bartley Effect: A flickering 10 HZ light appears brighter than a steady light of the same luminance (example of Broca- Sultzer effect)
- 19. Talbot-Plateau law: brightness of a fused temporally modulated stimulus is equal to the brightness of a steady light of the same average luminance
- 20. MaskingSimultaneous maskingExample: Crowding phenomenon in amblyopesBackward maskingExample: MetacontrastForward masking