How to randomise trials without following in successive ones

Participants are presented with color words written in different ink color. The

participants are required to name the ink color of the stimuli.

Each respond of the participant is recorded as a WAV file in each trial and also the reaction time is recorded.

Every trial includes: a fixation cross presented for 0.5 ms, then the stimulus (color word)presented for 2 seconds and a blank screen presented 0.5 ms. The voice recording and reactiontime calculation occurs during color word presentation.

The experiment includes several categories of color words presented as jpg image files which are placed in different folders.

The code chooses a random image from a folder in each trial. However, there is a

possibility that some stimuli with similar features, or the same exact stimulus could be presentedin successive trials. Thus, there is a need of restricting this possibility.

This could be done by defining some stimulus clusters and writing “if..else” codes

restricting choosing stimuli from the same clusters in successive trials.

The clusters are the following:

BlueInkColor: MSS.JPG; MCS.JPG; MJS.JPG; MZS.JPG; TMM.JPG; TKM.JPG; TSM.JPG; TYM.JPG

GreenInkColor: MZZ.JPG; MCZ.JPG; MJZ.JPG; MSZ.JPG; TYY.JPG; TKY.JPG; TMY.JPG; TSY.JPG

RedInkColor: MCC.JPG; MJC.JPG; MSC.JPG; MZC.JPG; TKK.JPG; TMK.JPG; TSK.JPG; TYK.JPG

YellowInkColor: MJJ.JPG; MCJ.JPG; MSJ.JPG; MZJ.JPG; TSS.JPG; TKS.JPG; TMS.JPG; TYS.JPG;

BlueColorWord: MSS.JPG; MSC.JPG; MSJ.JPG; MSZ.JPG; TMM.JPG; TMK.JPG; TMS.JPG; TMY.JPG

GreenColorWord: MZZ.JPG; MZC.JPG; MZJ.JPG; MZS.JPG; TYY.JPG; TYK.JPG; TYM.JPG; TYS.JPG

RedColorWord: MCC.JPG; MCJ.JPG; MCS.JPG; MCZ.JPG; TKK.JPG; TKM.JPG; TKS.JPG; TKY.JPG

YellowColorWord: MJJ.JPG; MJC.JPG; MJS.JPG; MJZ.JPG; TSS.JPG; TSK.JPG; TSM.JPG; TSY.JPG

Finally, those images who have the exact same name (e.g., MSS.JPG) should not follow in

successive trials.

Here is the part of the code where I need to add the new code to not repeat the trials.The data set contains 64 trials all together.

% Run experimental trials

for exp_i = 1 : length(experiment_order)

% Calculate image position (center of the screen)

fname = [];

if experiment_order{exp_i}{1} == 0

%tr uyumlu

fname= ['TurkceUyumlu/' tr_uyumlu_dosyalar(2+experiment_order{exp_i}{2}).name];

elseif experiment_order{exp_i}{1} == 1

%tr uyumsuz

fname= ['TurkceUyumsuz/' tr_uyumsuz_dosyalar(2+experiment_order{exp_i}{2}).name];

elseif experiment_order{exp_i}{1} == 2

%ing uyumlu

fname= ['ingilizceUyumlu/' ing_uyumlu_dosyalar(2+experiment_order{exp_i}{2}).name];

elseif experiment_order{exp_i}{1}== 3

%ing uyumsuz

fname= ['ingilizceUyumsuz/' ing_uyumsuz_dosyalar(2+experiment_order{exp_i}{2}).name];

end

img = imread(fname);

img_texture = Screen('MakeTexture', myWindow, img);

imageSize = size(img);

pos = [(W-imageSize(2))/2 (H-imageSize(1))/2 (W+imageSize(2))/2 (H+imageSize(1))/2];

% Show fixation cross

drawCross(myWindow,W,H);

tFixation = Screen('Flip', myWindow);

while(GetSecs - tFixation) < fixationDuration

WaitSecs(0.05);

end

[Jon]

Sorry, I'm not really clear on what is considered a repetition of an exact or similar image.

Can you please provide an examples of a valid sequence of files, and an example of an invalid sequence of files, and maybe a brief comment explaining why, exactly the invalid sequence should be rejected (what exactly is wrong with it).

Thanks

[Amra Feta]

For invalid sequence of files: All images with the same inkcolor should not follow each other, all images with tthe same colorword should not follow each other and all images with the same word file like mzz.jpg and another mzz.jpg should not follow each other.

Everything else is valid like a random ordering from onne inkcolor(like the blue one ) to anotther ink color like red.

[Jon]

Sorry, your explanation helps a little, but I'm still not really understanding how this works, I don't know what the difference is between an "inkcolor" and a "colorword" and do you need to pick one of each, two files total for each trial etc.

I think the simplest thing would be to provide and example list of a valid sequence of files, and then an example list of an invalid sequence of files, and a brief explanation of what is invalid in the invalid sequence.

[Amra Feta]

Attached is an example how I show the valid invalid sequences when I run the code. Inkcolor (just a blue/yellow/green/red screen) and colorword(words color is blue/yellow/red/green eg. red will be writen in word red and with color red). Hope this is clearer.

[Jon]

Hi Amra Although your Excel sheet gave me some further idea of what you were trying to achieve, I was still not clear on how the selections in the table related to the 8 groups in your original post. I also don' t understand, on a given trial, do you sometime select an image from a colorWord group sometimes from a inkColor group? If so, is there a deterministic pattern to that too, for example alternate from colorWord group to inkColor group, or is that also random. If so is it acceptable for that to repeat, e.g. two inkColor groups in a row.

Sorry, we are having such communciation problems. Please try once more, and then if I can't understand, I should probably give up so I don't waste your time further. Maybe someone else can pick up on this who finds what you are trying to explain more obvious.

In the meantime, you may also want to look at this previous question, https://www.mathworks.com/matlabcentral/answers/169274-how-can-i-have-random-numbers-with-criteria#answer_164343and in particular the answer from @John D&#39;Errico which I think may give you valuable insights into the general type of problem you are trying to solve.

[Amra Feta]

Hi Jon, Once again thank you for your time and considaration.

Image selection goes with language and congruency.

Ex. First trial is one image among English congruent files, then second trial is one image from Turkish congruent, third triql is one image from English incongruent files, fourth trial is one image from Turkish incongruent files and so on. So original trial selection does not consider color word or ink color at all.

[Jon]

I'm afraid we have some sort of "impedance matching" problem on trying to understand each other. You keep trying and I keep not understanding. I still have no idea how what you say here relates to selecting from the 8 groups in your original post.

[Jon]

OK, I think I finally got it. Thanks for your patience.

If I am understanding correctly I think this code should do what you are asking, or will come close and you can adapt.

Please let me know if you have any questions on how it works or if I missed something.

Thank here go to @John D'Errico @John D&#39;Erricofor his post https://www.mathworks.com/matlabcentral/answers/169274-how-can-i-have-random-numbers-with-criteria#answer_164343 which gives the key idea for this.

% define parameters
numPresentations = 64; % number of presentations
numColorWords = 4; % number of possible word names,  to be displayed
numColorInks = 4; % number of possible ink colors to be used
% define folder names, English, Turkish
folderNames = {'ingilizceUyumlu', 'TurkceUyumsuz'}

% define color codes red,green,blue, yelow,
% first row for English, second row for Turkish
% columns are colors
colorCode = {'C','Z','S','J';
             'K','Y','M','S'};

% define language code
languageCode  = {'M','T'}; % prefix English, Turkish

% generate random seqences of non-repeating color words, and ink colors
% integer values correspond to indices in the color code array
iColorWord = norepeat(numColorWords,numPresentations); % nonrepeating sequence of values between 1 and 4
jColorInk = norepeat(numColorInks,numPresentations); % nonrepeating sequence of values between 1 and 4

% generate random sequence of language, we don't care if this repeats
kLanguage = randi(2,numPresentations); % sequence of 1,2 

% generate file paths using folder and color code tables
fileNames = cell(numPresentations,1); % preallocate cell array to hold names
for k = 1:numPresentations
    
    kL = kLanguage(k); % local name to make more readable 1 or 2 for English or Turkish
    folder = folderNames{kL};
    language = languageCode{kL};
    word = colorCode{kL,iColorWord(k)};
    ink = colorCode{kL,jColorInk(k)};
    file = [language, word, ink,'.JPG']; % for example MSZ.JPG
    fileNames{k} = fullfile(folder,file);
end
    
function r = norepeat(k,n)
% generate n random integers between 1 and k without repetition
% from John D'Errico (Much Thanks!)
% https://www.mathworks.com/matlabcentral/answers/169274-how-can-i-have-random-numbers-with-criteria#answer_164343
r = 1 + mod(cumsum([randi(k),randi(k-1,[1,n-1])]),k);
end

Here is a partial listing of the file names that are generated by a run of the code

'TurkceUyumsuz\TSM.JPG'

'ingilizceUyumlu\MSJ.JPG'

'TurkceUyumsuz\TYM.JPG'

'TurkceUyumsuz\TKY.JPG'

'ingilizceUyumlu\MSC.JPG'

'TurkceUyumsuz\TYY.JPG'

'ingilizceUyumlu\MJC.JPG'

'ingilizceUyumlu\MSS.JPG'

'ingilizceUyumlu\MZC.JPG'

'ingilizceUyumlu\MCZ.JPG'

'ingilizceUyumlu\MSC.JPG'

'TurkceUyumsuz\TKY.JPG'

'TurkceUyumsuz\TMK.JPG'

'TurkceUyumsuz\TKS.JPG'

'TurkceUyumsuz\TYK.JPG'

'ingilizceUyumlu\MJJ.JPG'

'TurkceUyumsuz\TYK.JPG'

'TurkceUyumsuz\TKY.JPG'

'ingilizceUyumlu\MSJ.JPG'

'ingilizceUyumlu\MJC.JPG'

'TurkceUyumsuz\TKS.JPG'

'ingilizceUyumlu\MSZ.JPG'

'TurkceUyumsuz\TSK.JPG'

[Amra Feta]

Omg thank you so much @Jon you saved me really !!! Also a big thanks from my friend. The only thing left is where should I put this in her code like you saw the code because we tried it with her it is still not working for us because we are nott putting it in the right place I guess.

Answer 1

[Jon]

OK, I think I finally got it. Thanks for your patience.

If I am understanding correctly I think this code should do what you are asking, or will come close and you can adapt.

Please let me know if you have any questions on how it works or if I missed something.

Thank here go to @John D'Errico @John D&#39;Erricofor his post https://www.mathworks.com/matlabcentral/answers/169274-how-can-i-have-random-numbers-with-criteria#answer_164343 which gives the key idea for this.

% define parameters
numPresentations = 64; % number of presentations
numColorWords = 4; % number of possible word names,  to be displayed
numColorInks = 4; % number of possible ink colors to be used
% define folder names, English, Turkish
folderNames = {'ingilizceUyumlu', 'TurkceUyumsuz'}
% define color codes red,green,blue, yelow,
% first row for English, second row for Turkish
% columns are colors
colorCode = {'C','Z','S','J';
    'K','Y','M','S'};
% define language code
languageCode  = {'M','T'}; % prefix English, Turkish
% generate random seqences of non-repeating color words, and ink colors
% integer values correspond to indices in the color code array
iColorWord = norepeat(numColorWords,numPresentations); % nonrepeating sequence of values between 1 and 4
jColorInk = norepeat(numColorInks,numPresentations); % nonrepeating sequence of values between 1 and 4
% generate random sequence of language, we don't care if this repeats
kLanguage = randi(2,numPresentations); % sequence of 1,2 
% generate file paths using folder and color code tables
fileNames = cell(numPresentations,1); % preallocate cell array to hold names
for k = 1:numPresentations
    
    kL = kLanguage(k); % local name to make more readable 1 or 2 for English or Turkish
    folder = folderNames{kL};
    language = languageCode{kL};
    word = colorCode{kL,iColorWord(k)};
    ink = colorCode{kL,jColorInk(k)};
    file = [language, word, ink,'.JPG']; % for example MSZ.JPG
    fileNames{k} = fullfile(folder,file);
end

function r = norepeat(k,n)
% generate n random integers between 1 and k without repetition
% from John D'Errico (Much Thanks!)
% https://www.mathworks.com/matlabcentral/answers/169274-how-can-i-have-random-numbers-with-criteria#answer_164343
r = 1 + mod(cumsum([randi(k),randi(k-1,[1,n-1])]),k);
end

Here is a partial listing of the file names that are generated by a run of the code

'TurkceUyumsuz\TSM.JPG'

'ingilizceUyumlu\MSJ.JPG'

'TurkceUyumsuz\TYM.JPG'

'TurkceUyumsuz\TKY.JPG'

'ingilizceUyumlu\MSC.JPG'

'TurkceUyumsuz\TYY.JPG'

'ingilizceUyumlu\MJC.JPG'

'ingilizceUyumlu\MSS.JPG'

'ingilizceUyumlu\MZC.JPG'

'ingilizceUyumlu\MCZ.JPG'

'ingilizceUyumlu\MSC.JPG'

'TurkceUyumsuz\TKY.JPG'

'TurkceUyumsuz\TMK.JPG'

'TurkceUyumsuz\TKS.JPG'

'TurkceUyumsuz\TYK.JPG'

'ingilizceUyumlu\MJJ.JPG'

'TurkceUyumsuz\TYK.JPG'

'TurkceUyumsuz\TKY.JPG'

'ingilizceUyumlu\MSJ.JPG'

'ingilizceUyumlu\MJC.JPG'

'TurkceUyumsuz\TKS.JPG'

'ingilizceUyumlu\MSZ.JPG'

'TurkceUyumsuz\TSK.JPG'

[Jon]

I realized I had posted my code, which really was an answer as a comment. I moved it here so that it get categorized properly as an answer.

Just to keep track of things, if you could put you last comment (which got listed as an "answer" ) ,as a comment here, and delete your "answer" then everything would be back where it belonged.

[Jon]

Regarding incorporating this into your existing code, I think you could do it something like what is shown below. In the first loop you compute your list of random file names and save them in the cellarray fileNames. In the next loop, you go through all of the filenames reading in each image file and presenting them to the user. You may have to modify this a little but it should give you some idea to get started.

% define parameters
numPresentations = 64; % number of presentations
numColorWords = 4; % number of possible word names,  to be displayed
numColorInks = 4; % number of possible ink colors to be used
% define folder names, English, Turkish
folderNames = {'ingilizceUyumlu', 'TurkceUyumsuz'}
% define color codes red,green,blue, yelow,
% first row for English, second row for Turkish
% columns are colors
colorCode = {'C','Z','S','J';
    'K','Y','M','S'};
% define language code
languageCode  = {'M','T'}; % prefix English, Turkish

% Prepare list of randomly selected file names
% generate random seqences of non-repeating color words, and ink colors
% integer values correspond to indices in the color code array
iColorWord = norepeat(numColorWords,numPresentations); % nonrepeating sequence of values between 1 and 4
jColorInk = norepeat(numColorInks,numPresentations); % nonrepeating sequence of values between 1 and 4
% generate random sequence of language, we don't care if this repeats
kLanguage = randi(2,numPresentations); % sequence of 1,2 
% generate file paths using folder and color code tables
fileNames = cell(numPresentations,1); % preallocate cell array to hold names
for k = 1:numPresentations 
    kL = kLanguage(k); % local name to make more readable 1 or 2 for English or Turkish
    folder = folderNames{kL};
    language = languageCode{kL};
    word = colorCode{kL,iColorWord(k)};
    ink = colorCode{kL,jColorInk(k)};
    file = [language, word, ink,'.JPG']; % for example MSZ.JPG
    fileNames{k} = fullfile(folder,file);
end

% Peform the experiment

for exp_i = 1 : numPresentations
    % read in the image file
    img = imread(fileNames{exp_i});
    
    % Calculate image position (center of the screen)
    img_texture = Screen('MakeTexture', myWindow, img);
    imageSize = size(img);
    pos = [(W-imageSize(2))/2 (H-imageSize(1))/2 (W+imageSize(2))/2 (H+imageSize(1))/2];
    
    % Show fixation cross
    drawCross(myWindow,W,H);
    tFixation = Screen('Flip', myWindow);
    
    while(GetSecs - tFixation) < fixationDuration
        WaitSecs(0.05);
    end
end
    
    % define function to generate integers without repetition
    function r = norepeat(k,n)
    % generate n random integers between 1 and k without repetition
    % from John D'Errico (Much Thanks!)
    % https://www.mathworks.com/matlabcentral/answers/169274-how-can-i-have-random-numbers-with-criteria#answer_164343
    r = 1 + mod(cumsum([randi(k),randi(k-1,[1,n-1])]),k);
    end

[Jon]

I see you accepted the answer - thanks. Hopefully it is all working for you now! Let me know if you have any more problems

[Amra Feta]

Hi @Jon Yes itt is clear the only thing i would need to ask you is where should I insert this code inside my friends already existing code. Here is her code attached.

[Jon]

I already tried to show you in the above edited code, but here it is more explicitly in the attahced file where I have modified your code. I left in some of your code, but commented it out if I thought it was no longer needed. In case I was wrong, and it was needed you can uncomment it. Otherwise you can delete out all of those lines.

Here's an overview:

First you randomly generate the names of the files to be presented and save them to cellarray fileNames.

Then in the experiment you just open up each file in the list and present it.

The function for generating the non-repeating random indices is at the bottom with other helper functions.

I set the numPresentations = 64, this is the total number of images to be shown in an experiment. Not sure if this is correct or not, but you can change it.

Answer 2

[Amra Feta]

Hi @Jon,

I will give it one more try since this is for a friend of mine. So what she ttold me for the 8 original files :

English congruent file:

blue color word in blue ink,

green color word in green ink,

red color word in red ink,

yellow color word in yellow ink

Turkish congruent file:

blue color word in blue ink,

green color word in green ink,

red color word in red ink,

yellow color word in yellow ink

The only difference is that the color words are in Turkish

In incongruent files, the ink color and the color words are mismatched

In English incongruent file the color words are in English whereas in Turkish incongruent they are in Turkish

What she wants is to go through the files and to not repeat for example you have blue color word in blue ink then the next one should be either green color word in green ink or an incongruent one to not repeatt the blue color word in blue ink. The only thing I need is how to call i file in matlab and go through it than to not repeat the trial.