What's new?

September 19, 2011

• Palamedes version 1.3.0 is here
  • Version 1.3.0 allows alternative schemes to incorporate lapses into psychometric function models. Alternative fitting schemes may be performed using the optional argument 'lapseFit' (all functions that involve PF fits accept it). The default value is 'nAPLE' ('non-Asymptotic Performance Lapse Estimation'), which is the method advocated by Wichmann & Hill (2001a). If during testing a stimulus level is used which is so high that it can be assumed that errors observed at this asymptotic intensity can only be due to a lapse, consider using 'jAPLE' ('joint APLE'), which is identical to 'nAPLE' except that the probability correct at the highest intensity level used will be modeled as 1 - lambda (i.e., errors observed there are assumed to be due only to lapse). A third option is 'iAPLE' ('isolated APLE'), in which the probability correct at the highest stimulus level will be modeled as 1 - lambda. Observations at other stimulus intensities will then be modeled by fitting a PF with threshold and slope parameters free to vary (if so desired), while the lapse rate is fixed at the value obtained earlier at the highest stimulus intensity. For more information go here.
  • Version 1.3.0 allows one to constrain the guess rate and the lapse rate to be equal, as would be appropriate in, say, a task involving bistable percepts. Use optional argument 'gammaEQlambda', followed by 1, [or logical(true)], to set this constraint (accepted by all functions that involve fitting PFs). Lapse rates can still beconstrained in a variety of ways and guess rates will follow suit.
  • Some other, very minor, changes were made. See History.m for the boring details.
  • Overall, this was quite an extensive upgrade. Despite elaborate testing, bugs may remain. Please help us find any bugs by submitting bug reports.
  • The new features of version 1.3.0 are demonstrated in PAL_PFML_LapseFit_Demo and PAL_PFML_gammaEQlambda_Demo in the PalamedesDemos folder.
• Added a few new FAQs

• Palamedes version 1.2.0 is here

  • Most important change is that functions that fit single Psychometric Functions using a Maximum Likelihood criterion (i.e.., PAL_PFML_Fit, PAL_PFML_BootstrapParametric, PAL_PFML_BootstrapNonParametric, PAL_PFML_GoodnessOfFit) now accept a 0D, 1D, 2D, 3D or 4D (!) parameter grid through which to perform a brute force search for initial guesses to use in the iterative Simplex search procedure. The old method of providing a vector containing one initial guessed value for each of the parameters still works but when you do this, you will be encouraged to look into using the new method and warned that in some non-specified time in the future the old method will disappear from Palamedes. Confused? Not to worry. PAL_PFML_Demo has been changed to make use of this new feature and we created a new demo (PAL_PFML_SearchGrid_Demo) that specifically demonstrates use of the new feature.

  • Also, psychometric functions, inverse psychometric functions, and first derivatives (dy/dx) of psychometric functions  are now all incorporated in the existing functions PAL_CumulativeNormal, PAL_Weibull, PAL_Gumbel, PAL_HyperbolicSecant, and PAL_Logistic. For example, to get the value at which the logistic with alpha = 0, beta =1, gamma = 0.5, and lambda = .03 evaluates to .8 use: x = PAL_Logistic([0 1 .5 .03],.8,’inverse’), to find the slope of the tangent line to the above function at x = 0, use: tangentslope = PAL_Logistic([0 1 .5 .03],0,’derivative’). The older inverse PF functions (e.g., PAL_inverseLogistic) still exist but are now obsolete and when you use them, you will be encouraged to use the above strategy instead and warned that at some non-specified time in the future these functions will disappear from Palamedes.

  • Some other minor changes were made (see history.m for details).

• Posted Palamedes version 1.1.1. Very minor changes only. See PAL_History for details.

• Palamedes version 1.1.0 is here
  • Version 1.1.0 introduces custom reparametrization of the parameters of PFs in multi-condition fitting situations. See our overview page, PAL_PFLR_CustomDefine_Demo in the PalamedesDemos folder, or type 'help PAL_PFML_CustomDefine' for more information. This was quite a substantive overhaul of many functions (including PAL_PFML_FitMultiple, PAL_PFML_BootstrapParametricMultiple, PAL_PFML_BootstrapNonParametricMultiple, PAL_PFML_GoodnessOfFitMultiple, PAL_PFLR_ModelComparison, as well as many 'behind-the-scenes' functions). Though we spent quite a bit of time testing, bugs might remain and we would appreciate any bug reports. Of course, all previous functionality has been retained (whatever worked with previous versions of Palamedes, will still work).
  • PAL_PFML_FitMultiple can now return the number of free parameters in the model fitted.
  • Added a function PAL_PFML_LLsaturated which returns the Log Likelihood of the saturated model as well as the number of parameter estimates in the saturated model.
  • Some additional minor changes were made (see history.m for the details).
  • Added a few Q and As on our frequently asked questions page.
• We are already working on Palamedes version 1.2.0 which will introduce more Signal Detection routines.

October 27, 2009

• Palamedes version 1.1.0 coming soon.
  • New feature: custom reparametrization of PF parameters across mutiple conditions. For example:
  • Need to fix the threshold values values in conditions 1, 3, and 6 to equal 1, 2, and pi respectively but have thresholds in conditions 2, 4, 5, and 7 adhere to 'threshold(condition) = a x sin(b x condition^2) where 'a' and 'b' are free parameters? We understand.
  • Wish to compare the model above to an identical one except that parameter 'a' is fixed to equal sqrt(3)? Absolutely.
  • Wish to apply another set of unlikely constraints on slopes, guess rates, and/or lapse rates? No problem.
  • For just one example of what you will be able to do, click here.

October 1, 2009

• Posted version 1.0.2 . Very minor changes only:
  • Suppressed a few inconsequential Matlab-generated warnings
  • Corrected some filenames in help comments
  • For details, view history.m in Palamedes folder

September 17, 2009

• Posted version 1.0.1. Very minor changes only:
  • Added a demo script: PAL_SDT_DPtoPCacrossM_demo
  • Other Demo scripts no longer hijack figures that happen to be open
  • Some SDT routines now go easier on RAM
  • Added warning message in PAL_PFML_BootstrapNonParametricMultiple
  • Modified warning message in PAL_PFML_BootstrapNonParametric
  • Added file History.m which records changes across versions
• Download page contains links to two zip archives
  
  • Full Palamedes version 1.0.1
  • Upgraded files only (replace existing files with downloaded files)