rmeddis@28: % ------------------------------------------------------- psychometricFunction
rmeddis@28: function [psy, levelsBinVector, binFrequencies, nNo, nYes]=...
rmeddis@28:     psychometricFunction(levels, responses, psyBinWidth)
rmeddis@28: % computes a psychometric function from rwo vectors (levels and responses)
rmeddis@28: % responses is a binary vectory (1=yes)
rmeddis@28: % psyBinWidth is the bin width (dB) of the output psychometric function
rmeddis@28: % this function is called by both fitPsychometricFunction and subjGUI
rmeddis@28: % for this reason it should notbe bundled with fitPsychometricFunction
rmeddis@28: 
rmeddis@28: binFrequencies=[]; nNo=[]; nYes=[];
rmeddis@28: if min(levels)+abs(psyBinWidth) < max(levels)
rmeddis@28:     % create a set of bins for the psychometric function
rmeddis@28:     levelsBinVector= min(levels): abs(psyBinWidth): max(levels);
rmeddis@28: else
rmeddis@28:     psy=[]; levelsBinVector=[];
rmeddis@28:     return
rmeddis@28: end
rmeddis@28: 
rmeddis@28: idx0=find(responses==0);	% isolate 'no'
rmeddis@28: z=levels(idx0);
rmeddis@28: nNo=hist(z, levelsBinVector);
rmeddis@28: 
rmeddis@28: idx1=find(responses>0);	% isolate 'yes'
rmeddis@28: y=levels(idx1);
rmeddis@28: nYes=hist(y, levelsBinVector);
rmeddis@28: 
rmeddis@28: if sum(nNo)==0 | sum(nYes)==0
rmeddis@28:         psy=[]; levelsBinVector=[];
rmeddis@28:     return             % yesses and nos required for a function
rmeddis@28: end
rmeddis@28: 
rmeddis@28: binFrequencies=nNo+nYes;
rmeddis@28: 
rmeddis@28: warning off MATLAB:divideByZero
rmeddis@28: psy=nYes./binFrequencies;        % psy is the proportion of 'yes' responses
rmeddis@28: warning on MATLAB:divideByZero
rmeddis@28: lastwarn('');
rmeddis@28: 
rmeddis@28: idx=~isnan(psy);	%remove empty bins
rmeddis@28: idx=(nYes>0) |(nNo>0);	%remove empty bins
rmeddis@28: psy=psy(idx);
rmeddis@28: levelsBinVector=levelsBinVector(idx);
rmeddis@28: binFrequencies=binFrequencies(idx);
rmeddis@28: nNo=nNo(idx);
rmeddis@28: nYes=nYes(idx);
rmeddis@28: 
rmeddis@28: % [nNo' nYes']
rmeddis@28: % [levelsBinVector' psy']
rmeddis@28: % plot(levelsBinVector,psy,['o'])