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version (28.6 KB) by Daniel Saunders
A graphical tool to build intuition about the psychophysical staircase procedure QUEST.


Updated 31 Mar 2016

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A program for building intuitions about how the QUEST (Watson and Pelli, 1983; Pelli and Farell, 1995) adaptive staircase procedure behaves, as far as choosing test levels and estimating a psychophysical threshold, and what is going on behind the scenes. Requires MATLAB and the Psychophysics Toolbox (Brainard, 1997).
To run, change the directory to QuestIntuition and type QuestIntuition.

Enter the initial assumptions for your QUEST procedure in the top box (I provide some defaults from the PsychToolbox's QuestDemo - for advice about setting them, "help QuestDemo") and then either let a simulated QUEST procedure run automatically (middle box), either one run at a time or simulating the distribution of estimates over multiple runs, or step manually one trial at a time (bottom box), noticing how the posterior and test level are updated with each response.

Daniel Saunders, 2016

Cite As

Daniel Saunders (2022). drsaunders/QuestIntuition (, GitHub. Retrieved .

MATLAB Release Compatibility
Created with R2008b
Compatible with any release
Platform Compatibility
Windows macOS Linux

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To view or report issues in this GitHub add-on, visit the GitHub Repository.
To view or report issues in this GitHub add-on, visit the GitHub Repository.