HCR - Psychophysical Measurement Methods

NOT_SURE_ABOUT_THIS Old notes taken really fast Psychophysical methods and procedures are useful in determining threshold.

For a perfect observer, threshold is the point where the stimulus can just be detected or where you just cannot detect the stimulus.

Humans are not perfect observers, and often thresholds are defined in probabilistic terms: for example, half the points presented would be detected and half would not.

Threshold variability most likely depends on neural noise.

Measurement of visual response can be achieved through several methods.

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• Psychophysical methods:
  • Methods of constant stimuli:
    • AT (Absolute Threshold):
      • Yes-No procedure.
      • 2AFC procedure.
    • DT (Differential Threshold).
  • Method of Limits:
    • **AT (Absolute Threshold*).
    • DT*** (Differential Threshold).
    • Staircase (modified methods of limits).
  • Methods of adjustment:
    • AT (Absolute Threshold).
    • DT (Differential Threshold).
  • Adaptive Methods:
    • Maximum Likelihood Methods (QUEST).