README for the MATLAB simulation programs related to Lesmes et al, Bayesian adaptive methods for estimating sensitivity thresholds in Yes-No and Forced-Choice Tasks
These simulation programs were used to generate the demonstration movie for simple YN detection (Movie 1). Please follow the following steps to run the simulation programs:
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1. Extract the programs from the downloaded .zip file.
2. Open MATLAB and go to the directory where you have extracted the zip file.
3. Launch the GUI of qYN simulator by typing 'setupQuickYN' and hit RETURN or ENTER in the MATLAB command window. This will open a GUI with the instruction, "Please choose the method for the appropriate detection task". There are four buttons but only one is currently available for clicking: quick YN.
4. Click the "quick YN" button on the GUI.
5. Click the "Setup Prior" button on the GUI (the loadPrior button is not yet functional). Another interface will be presented. To set the prior, please adjust the slides. For each parameter, independently adjust the mode (best guess) and dispersion (uncertainty) of the prior with the top and bottom sliders. The plot on the top left is the psychometric function that corresponds to the marginal modes of the three parameters. Adjusting the sliders will change the psychometric function. Changing the d' threshold parameter will move the psychometric function horizontally, changing the steepness parameter of the d' function will likewise change the steepness of the empirical YN psychometric function, and changing the decision criterion will change the false alarm rate. Using the sliders to change the uncertainty of these parameters will change the width of the marginal priors. The effect of changing uncertainty will be invisible if the presented psychometric function depends only on the mean. However, checking "Check to Display Posterior Samples during Simulation" box to display functions sampled from the Bayesian pdf will demonstrate the dispersion of psychometric function estimates as a function of parameter uncertainty.
6. Click on the "Setup Simulation" button after choosing the prior. In the next interface, you can choose the ground truth of the parameters. The sliders can be used to set the ground truth for each of the 2 sensitivity parameters and the decision parameter.
There is an option "Check to Display Functions Sampled from Posterior" to display psychometric functions from the posterior as the simulation unfolds. Without checking the box, only the function corresponding to marginal modes will be displayed.
7. Click on "Start Simulation". The quick YN movie will be shown in the next window (see caption of Movie 1 in the main text for a detailed description of the panels in the movie).