% StroopStimResponse.m
%
% This program presents stroop like stimuli and record keypress response.
% Written by YW, 2022

try
  clear all
  close all
  
  subid='3';
  subname='wangwu';
  
  % predefine parameters
  BlockNum=1;% how may block in this experiment
  StimDuration=2000;% 2000ms
  ISImin=1000;% the minmum interstimulus interval (ISI)
  ISImax=1500;% the maxmum interstimulus interval (ISI)
  TxtSize=100;% the size of the texts
  TxtFont='Arial'; % the font of the texts
  
  Words={'Red', 'Green', 'Blue'}; 
  StimColor={[255 0 0];[0 255 0];[0 0 255]};
  count=0;
  for i=1:length(Words)
    for j=1:length(StimColor)
      count=count+1;
      Stim(count).word=Words{i}; % stimulus word 
      Stim(count).color=StimColor{j};% stimulus color
    end
  end
  
  % to preset variables 'results' for recording data
  results.word = NaN*ones(BlockNum,length(Stim)); 
  results.color = NaN*ones(BlockNum,length(Stim));
  results.response = NaN*ones(BlockNum,length(Stim));
  results.reactiontime = NaN*ones(BlockNum,length(Stim)); 
  
  % open window
  screenNum=0;
  [wPtr,rect]=Screen('OpenWindow',screenNum);
  HideCursor;
  black=BlackIndex(wPtr);
  white=WhiteIndex(wPtr);
  monitorFlipInterval=Screen('GetFlipInterval', wPtr);
  hz=FrameRate(wPtr);
  StimDuration=round((StimDuration/1000)*hz); % the number of frames for stimulusduration
  ISIrange=round(((ISImax-ISImin)/1000)*hz); 
  ISImin=round((ISImin/1000)*hz); 
  ISI=round(rand(BlockNum,length(Stim))*ISIrange+ISImin);% the number of frames for neach trial's ISI in a range of ISImin and ISImax
  
  % blank the Screen 
  starttime=Screen('Flip',wPtr); % collect the time for the first flip with starttime
  for ii=1:BlockNum
    
    Screen('TextSize', wPtr , TxtSize);
    Screen( 'TextFont', wPtr ,TxtFont);
    StimRand=Stim(randperm(length(Stim))); % randomize all stimuli
    
    for jj=1:length(Stim)   
      TxtRect= Screen('TextBounds',wPtr,StimRand(jj).word); % get the size of each stimulus text 
      TxtLoc=[round(rect(3)/2-TxtRect(3)/2),round(rect(4)/2-TxtRect(4)/2)];  % compute the upperleft and lowerright location of each stimulus text, to make the text in the middle of the screen
      Screen('DrawText', wPtr, StimRand(jj).word, TxtLoc(1), TxtLoc(2),StimRand(jj).color);
      starttime=Screen(wPtr, 'Flip', starttime+(ISI(ii,jj)*monitorFlipInterval)); % time in secs
      [keys,RT] = waitTilltime(StimDuration*monitorFlipInterval,starttime);%time in secs
      starttime=Screen('Flip', wPtr);% time in secs
      
      %%% save keypress response
      if strcmp(StimRand(jj).word,Words{1})==1
        results.word(ii,jj)=1; % word1 'Red'
      elseif strcmp(StimRand(jj).word,Words{2})==1
        results.word(ii,jj)=2;% word2 'Green'
      elseif strcmp(StimRand(jj).word,Words{3})==1
        results.word(ii,jj)=3;% word3 'Blue'
      end
      results.color(ii,jj)=find(StimRand(jj).color~=0); % color 1=red,2=green, 3=blue
      
      if ~isempty(RT)
        results.reactiontime(ii,jj)=RT;
        results.key{ii,jj}=keys{1};
        
        if (results.key{ii,jj}=='f' && results.color(ii,jj)==1)...
          ||(results.key{ii,jj}=='j' && results.color(ii,jj)==2)...
          ||(results.key{ii,jj}=='k' && results.color(ii,jj)==3)
          results.response(ii,jj) = 1;% f for color red, j for color green, k for color blue are correct
        else
          results.response(ii,jj) = 0;% incorrect
        end
      end
    end
  end
  ISIlast=round(rand(1)*ISIrange+ISImin); % the last trial's ISI
  % blank the screen and wait a second
  Screen('FillRect',wPtr,white);
  Screen(wPtr, 'Flip', starttime+(ISIlast*monitorFlipInterval));
  
  % save the datafile to disc for each participant
  datafile=['StroopData_Sub' subid '_' subname];
  path=pwd;
  save ([path '\Data\' datafile '.mat'], 'results'); % save as mat file
  
  Screen('CloseAll');
  ShowCursor  
catch 
  Screen('CloseAll')
  rethrow(lasterror)
end