Is there a way to incorporate scripts into a for loop, instead of images as stimuli for an experiment?

I am working on creating a visual perception experiment, using PsychToolbox. The experiment will consist of 160 trials. In each trial, the subject is presented with a sequence of images (an object composed of simple shapes, followed by a masking image, followed by another simple-shape-object). In order to present the images in the proper sequence within each trial, I believe it will be easiest to make a separate script for each trial. Then, I want to use a for loop to randomly present each trial. Is this possible?

Here is an example code for one of the trials:

 image1 = imread('ccc.s.jpg');
 image2 = imread('ccc.dc.jpg');
 mask = imread('mask.jpg');

 Image1=Screen('MakeTexture', expWin, image1);
 Image2=Screen('MakeTexture', expWin, image2);
 Mask = Screen('MakeTexture', expWin, mask);

 Screen('DrawTexture', expWin, Image1);
 Screen('Flip', expWin);
 WaitSecs(0.300);

 Screen('DrawTexture', expWin, Mask);
 Screen('Flip', expWin); 
 WaitSecs(0.500);

 Screen('DrawTexture', expWin, Image2); 
 Screen('Flip', expWin);
 WaitSecs(0.300);

end

I will create 160 of these, 1 script for each trial. How do I use a for loop to randomly present the 160 trials, which will be created in external scripts?

And this is a portion of the experiment where the for loop will need to be incorporated:

% Open Screen
[expWin,rect]=Screen('OpenWindow',0);
% alternative: replace the above with smaller window for testing
% [expWin,rect]=Screen('OpenWindow',screenNumber,[],[10 20 1200 700]);

 % Get rid of cursor.
 HideCursor;

 % Choose a text size
 Screen('TextSize', expWin, 24);

 % Display Instructions Text
 DrawFormattedText(expWin, Instructions, 'center', 'center');
 Screen('Flip', expWin);

 %Display Practice Trials Next Text
 DrawFormattedText(expWin, PracticeTrialsNext, 'center', 'center');
 KbWait([], 3);
 Screen('Flip', expWin);

 ***% Practice Trial loop goes here***

 %Display Next Trial Text (This needs to somehow be incorporated into the
 %loops for practice trials and experimental trials)
 DrawFormattedText(expWin, NextTrial, 'center', 'center');
 Screen('Flip', expWin);

 %Display Experimental Trials Next Text
 DrawFormattedText(expWin, ExperimentalTrialsNext, 'center', 'center');
 KbWait([], 3);
 Screen('Flip', expWin);

 ***% Experimental Trial loop goes here***

 %Display End Text
 DrawFormattedText(expWin, End, 'center', 'center');
 KbWait([], 3);
 Screen('Flip', expWin);

 Screen('CloseAll')
 ShowCursor;
 fclose('all');

I also have a string of text that needs to follow each trial. Is there a simple way to incorporate this within the for loop as well?

Thanks in advance.

Answer 1

[Walter Roberson]

files_to_run = {'do_this', 'do_that', 'do_the_other', 'but_not_with_sizzors'};

thisfile = files_to_run{ 1 + floor( rand * length(files_to_run) ) };

run(thisfile)

[Larissa]

Thank you. This is definitely what I was looking for.

Do you know how to designate a folder to run scripts from, rather than listing each file that I want to run (I'd have to list 160 files, it seems much easier to list 1 folder)?

[Walter Roberson]

dir_of_files = 'C:\this\that\the_dir';

cd(dir_of_files);
fileinfo = dir( '*.m' );
files_to_run = {fileinfo.name};

thisfile = files_to_run{ 1 + floor( rand * length(files_to_run) ) };

run(thisfile)   %run() will handle .m file extension

Note: this code use the approach of changing to the directory and running the files from there. There is a different approach which involves reconstructing the full file names:

fileinfo = dir( fullfile(dir_of_files, '*.m') );
files_to_run = strcat(dir_of_files, '/', {fileinfo.name});

and you would still use run(), which knows how to handle the paths.

[Larissa]

That works perfectly. Thanks again!