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m-Alternative-Forced-Choice: Improving the Efficiency of the Method of Constant Stimuli




We explored several ways to improve the efficiency of measuring psychometric functions without resorting to adaptive procedures. a) The number m of alternatives in an m-alternative-forced-choice (m-AFC) task improves the efficiency of the method of constant stimuli. b) When alternatives are presented simultaneously on different positions on a screen rather than sequentially time can be saved and memory load for the subject can be reduced. c) A touch-screen can further help to make the experimental procedure more intuitive. We tested these ideas in the measurement of contrast sensitivity and compared them to results obtained by sequential presentation in two-interval-forced-choice (2-IFC). Qualitatively all methods (m-AFC and 2-IFC) recovered the characterictic shape of the contrast sensitivity function in three subjects. The m-AFC paradigm only took about 60% of the time of the 2-IFC task. We tried m=2,4,8 and found 4-AFC to give the best model fits and 2-AFC to have the least bias.

Author(s): Jäkel, F. and Hill, J. and Wichmann, FA.
Volume: 7
Pages: 118
Year: 2004
Month: February
Day: 0

Department(s): Empirische Inferenz
Bibtex Type: Poster (poster)

Digital: 0
Event Name: 7th T{\"u}bingen Perception Conference (TWK 2004)
Event Place: T{\"u}bingen, Germany
Language: en
Organization: Max-Planck-Gesellschaft
School: Biologische Kybernetik

Links: Web


  title = {m-Alternative-Forced-Choice: Improving the Efficiency of the Method of Constant Stimuli},
  author = {J{\"a}kel, F. and Hill, J. and Wichmann, FA.},
  volume = {7},
  pages = {118},
  organization = {Max-Planck-Gesellschaft},
  school = {Biologische Kybernetik},
  month = feb,
  year = {2004},
  month_numeric = {2}