PPT Slide

Two Alternative Forced Choice (2AFC)

Is the square on left or right?

• Observer must choose between two or more options, guessing if necessary

• Can also be done sequentially (two interval forced choice)

• Good for cases where observers may be less willing to guess

  - elderly people
  
  - blindsight patients

• Produces lower ‘thresholds’

• Shows that nervous system can register more information than one is aware of

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