Subject: Psychometric function fitting software From: "Daniel J. Tollin" <tollin(at)PHYSIOLOGY.WISC.EDU> Date: Fri, 24 May 2002 11:01:59 -0500Hi, Some old colleagues of mine from the Sensory Research Unit in the Department of Experimental Psychology at the University of Oxford have recently developed some very nice software that might be of interest to this group. Here is their message: ----------------------------------------------------------- >Announcing PSIGNIFIT: maximum-likelihood fitting and significance >testing software for psychometric functions. > > http://www.bootstrap-software.org/psignifit > >PSIGNIFIT is a multi-platform software tool for fitting sigmoidal >psychometric functions to psychophysical data, taking into account >possible "nuisance" parameters such as the observer's lapse rate, >assessing goodness-of-fit by Monte-Carlo simulation, and providing >confidence intervals via bootstrap methods. > >Our methods were described in our Perception and Psychophysics papers: > >Wichmann, F. A. & Hill, N. J. (2001a): The psychometric function I: >fitting, sampling and goodness-of-fit. Perception and Psychophysics >63(8), 1293-1313. > >Wichmann, F. A. & Hill, N. J. (2001b): The psychometric function II: >bootstrap based confidence intervals and sampling. Perception and >Psychophysics 63(8), 1314-1329. > >(N.B. in the papers we call our software "psychofit", but we have >changed the name in order to avoid confusion with Lewis Harvey's >software, also called "psychofit"). > >The software runs as a standalone command-line utility, but is easier to >use when integrated with Matlab: a Matlab "mex-file" version of the >engine is available, along with the PSIGNIFIT toolbox, a set of Matlab >functions that can be used to view and assess the results. > >With the latest version (2.5.4) we believe we have got out most of the >significant bugs that were hindering the toolbox's cross-platform >usefulness - confident enough, at least, to make this announcement at last. > >The website also contains reports of some of our recent research into >the factors affecting goodness-of-fit and confidence interval widths, >and into the accuracy of these and other confidence interval methods. > > >Jeremy Hill, D.Phil. http://www.kyb.tuebingen.mpg.de/~jez >Felix Wichmann, D.Phil. http://www.kyb.tuebingen.mpg.de/~felix > >psignifit(at)bootstrap-software.org > Cheers, Daniel J. Tollin, Ph.D. Assistant Scientist University of Wisconsin FAX: (608)-265-5512 Department of Physiology Phone:(608)-265-5143 290 Medical Sciences Building tollin(at)physiology.wisc.edu 1300 University Avenue Madison, WI 53706