Abstract
A constrained generalized maximum likelihood routine for fitting psychometric functions is proposed, which determines optimum values for the complete parameter set—that is, threshold and slopeas well as for guessing and lapsing probability. The constraints are realized by Bayesian prior distributions for each of these parameters. The fit itself results from maximizing the posterior distribution of the parameter values by a multidimensional simplex method. We present results from extensive Monte Carlo simulations by which we can approximate bias and variability of the estimated parameters of simulated psychometric functions. Furthermore, we have tested the routine with data gathered in real sessions of psychophysical experimenting.
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The study was supported by the Deutsche Forschungsgemeinschaft (Re 337/7) and by the Friedrich Baur Foundation (medical faculty of the Ludwig-Maximilians-Universität München).
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Treutwein, B., Strasburger, H. Fitting the psychometric function. Perception & Psychophysics 61, 87–106 (1999). https://doi.org/10.3758/BF03211951
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DOI: https://doi.org/10.3758/BF03211951