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