Error using Screen- DrawDots

Hello, when I try to run the PychToolBox experiment code below (on MATLAB R2023b), I receive the following error:

Error using Screen

Usage:

[minSmoothPointSize, maxSmoothPointSize, minAliasedPointSize, maxAliasedPointSize] = Screen('DrawDots', windowPtr,

xy [,size] [,color] [,center] [,dot_type][, lenient]);

Error in spaital_temporal (line 153)

Screen('DrawDots', wptr, TargetLocGrid, TargetSize, [255 255 255], []);

I can't figure out what I do wrong. Can anyone help me out with it?

% clean start:)
clear all
close all
clc
%% SpatioTemporal Replication proejct 
KbName('UnifyKeyNames'); % keyboard
Experimenter = -3;
Participant = -3;
Scanner = -3;

%% Subject information
subName = input('Subject Initials:  ', 's');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% directory setting 
genDir = '/Users/irmakergin/Desktop/yeshurun2003_rescue/data';
functions = '/Users/irmakergin/Desktop/yeshurun2003_rescue/data/_FUNC';
cd(functions)

%addpath(genpath(fullfile(genDir,'_FUNC')));
dataDir = fullfile(genDir,'_DATA','behavior',subName);
if ~exist(dataDir) &&  ~strcmp(subName,'tes'), mkdir(dataDir); end
datas = getAllFiles(dataDir,'*.mat',1); %function didn't work
runN=length(datas)+1;
dataName = fullfile(dataDir,sprintf('exp1_%s_%d',subName,length(datas)+1)); 
%% screen setting
bdgcol = 128;
Screen('Preference', 'SkipSyncTests', 1);
ScreenNum = max(Screen('Screens'));
[wptr,rect]=Screen('OpenWindow',ScreenNum,[0 0 0]);
Screen('BlendFunction', wptr, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

% Screen('HideCursorHelper', wptr);
[cx, cy] = RectCenter(rect);
ifi = 1/85;

Screen('TextSize',wptr, 40);

% Screen('HideCursorHelper', wptr);
[cx, cy] = RectCenter(rect);
ifi = 1/85;

Screen('TextSize',wptr, 40);

%% experiment matrix design

fixaSz = 5;
totalTrial=864;
cond=[0,1]; % 1: cued 0: uncued
loc=[1:6];
type=[1,2]; % 1: single disk, 2: two disks
ISI_base=[1,2,3];
iteration=3; % this should be 12

[cueing,tarType,tarLoc,ISI]= ...
    BalanceFactors(iteration,1,cond,type,loc,ISI_base);

trialNum=1:length(cueing);
emat=[cueing,tarType,tarLoc,ISI];

if ~strcmp(subName,'tes'),save(dataName,'emat');end

%% experiment loop
Screen('DrawText',wptr,'start',cx/1.1,cy,[255 255 255]);
Screen('Flip',wptr); 

scanPulse = 0;
while scanPulse ~= 1
    [keyIsDown, ~, keyCode] = KbCheck(Participant);
%     [keyIsDown, ~, keyCode] = PsychHID('KbCheck');
    if keyIsDown
        if  keyCode(KbName('s'))
            scanPulse = 1;
            break;
        end
    end
    WaitSecs(0.005);
end


TargetSize=deg2pixel(3);

% penWidth=round(deg2pixel(0.3));
penWidth=6;

% 0 3 6 9 13 16
ecc_vars=[0,deg2pixel(3), deg2pixel(6),deg2pixel(9),deg2pixel(13),deg2pixel(16)];
signSelect=[-1,1];

response=[];

%Time in frames
SOA=round(0.094/ifi); 
fixLen=round(1/ifi);
allList=[];
for tr=1:length(emat)
    %cueing,tarType,tarLoc,ISI
    emat(tr,:)
    
    tList=[9 10 11]; tLength1=tList(randperm(3,1));
    tISI_list=[1,2,3]; tISI=tISI_list(emat(tr,4));
    tLength2=4;

    
    TargetLocGrid=[cx+(ecc_vars(emat(tr,3))*signSelect(round(rand)+1)), cy];
    TargetLocGrid=round(TargetLocGrid);
    %fixation
    for iter = 1:fixLen
        Screen('FillOval',wptr,255*[0,0,1],[cx-fixaSz,cy-fixaSz,cx+fixaSz,cy+fixaSz]);
        Screen('Flip',wptr);
    end
    
    % cue
    if   emat(tr,1) ==1
        for iter = 1:fixLen
        Screen('DrawLine', wptr,255*[0,1,0], round(TargetLocGrid(1)-deg2pixel(1)),...
            round(cy-deg2pixel(0.5)-TargetSize/2), round(TargetLocGrid(1)+deg2pixel(1)), round(cy-deg2pixel(0.5)-TargetSize/2), penWidth);
 
        Screen('Flip',wptr);
        end
    else
        for iter = 1:fixLen
            Screen('DrawLine', wptr,255*[0,1,0], ...
                cx-(rect(3)/2),...
                round(cy-deg2pixel(0.5)-TargetSize/2), ...
                cx+(rect(3)/2),...
                round(cy-deg2pixel(0.5)-TargetSize/2),...
                penWidth);
            Screen('DrawLine', wptr,255*[0,1,0], ...
                cx-(rect(3)/2),...
                round(cy+deg2pixel(0.5)+TargetSize/2),...
                cx+(rect(3)/2), ...
                round(cy+deg2pixel(0.5)+TargetSize/2),...
                penWidth);
            Screen('Flip',wptr);
        end
        
    end

        % SOA
    for iter = 1:SOA % 94 ms
%         Screen('FillOval',wptr,255*[0,0,1],[cx-fixaSz,cy-fixaSz,cx+fixaSz,cy+fixaSz]);
        Screen('Flip',wptr);
    end
    
    Screen('Flip',wptr);

    % Target
%     
%     tLength1=100;
%     tLength2=100;
    if emat(tr,2) ==1
        for iter = 1:tLength1
            Screen('DrawDots', wptr, TargetLocGrid, TargetSize, [255 255 255], [], 2);
            %         Screen('DrawDots', wptr, [dotXpos dotYpos], dotSizePix, dotColor, [], 2);
            Screen('Flip',wptr);
        end
        
    elseif emat(tr,2)==2
        for on=1:tLength2
            Screen('DrawDots', wptr, TargetLocGrid, TargetSize, [255 255 255], [], 2);
            Screen('Flip',wptr);
        end
        
        for gap=1:tISI
            Screen('FillRect', wptr, [0 0 0]);
            Screen('Flip',wptr);
        end
        
        for off=1:tLength2
            Screen('DrawDots', wptr, TargetLocGrid, TargetSize, [255 255 255], [], 2);
            Screen('Flip',wptr);
        end
        
        
    end
    
    Screen('Flip',wptr);
%     RT_S=GetSecs;
    scanPulse = 0;
    while scanPulse ~= 1
        response(tr,1)=9; t1=GetSecs;
        [keyIsDown, ~, keyCode] = KbCheck(Participant);
%         [keyIsDown, ~, keyCode] = PsychHID('KbCheck');

        if keyIsDown
            if keyCode(KbName('1!'))
                response(tr,1) = 1;
                response(tr,2)=GetSecs-t1 ;
                break;
                
            end
            
            if keyCode(KbName('2@'))
                response(tr,1) = 2;
                response(tr,2)=GetSecs-t1 ;
                break;
            end
        end
    end
    RT_E=GetSecs;
%     RTs=RT_E-RT_S;
    allList=[allList; tr emat(tr,:) response(tr,:)];
    save(dataName,'emat','response','allList');

end


%put accuracy
 allList(:,end+1)= allList(:,3) == allList(:,6)


WaitSecs(1);
sca;

Answer 1

[Walter Roberson]

    TargetLocGrid=[cx+(ecc_vars(emat(tr,3))*signSelect(round(rand)+1)), cy];
    

Notice that uses [A,B] . Unless something in the one of the two expressions is an empty variable, the result is going to be multiple columns with the y in the second column

    [cx, cy] = RectCenter(rect);

so cy is a scalar. And since you cannot [A,B] together a column vector with more than one row and a scalar, in order for TargetLocGrid not to have produced a computation error, the variable must now be a 1 x N vector, probably 1 x 2

Screen('DrawDots', wptr, TargetLocGrid, TargetSize, [255 255 255], [], 2);

And the variable is passed in the xy slot.

http://psychtoolbox.org/docs/Screen-DrawDots

“xy” is a two-row vector containing the x and y

coordinates of the dot centers, relative to “center” (default center is [0 0]).

So xy must have two rows. But your TargetLocGrid only has one row.

The semantics is that the xy should have a row of x coordinates of pixel centers and a row of y coordinates of pixel centers, and that TargetSize should be a vector of corresponding dot sizes. If you are only drawing one pixel then that would mean that the xy should be a 2 x 1 column vector, not a 1 x 2 row vector.

[Irmak]

Thank you so much! I am still not sure how to make the code work tho... Can you maybe show me the corrected version?

[Walter Roberson]

    TargetLocGrid=[cx+(ecc_vars(emat(tr,3))*signSelect(round(rand)+1)); cy];

Just change the comma to semi-colon.

[Irmak]

Thank you! I already tried that after seeing your comment but it didn’t work, I am still having the same error

Answer 2

[hailing]

I received the same error today. I changed the number 2 into 3, and it just went well again. Maybe you can try this:

Screen('DrawDots', wptr, TargetLocGrid, TargetSize, [255 255 255], [], 3);