Waiting for keypresses to continue

Question

Marika Mariano 2022-6-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1749490-waiting-for-keypresses-to-continue

回答： T.Nikhil kumar 2023-10-26

Hello everyone,

I'm writing a script in which one or two subjects have to press a key (alone or toghether) to switch on a lightbulb. To record they keypresses I'm using the function Kbqueuecheck. However, using this function I am able to say the script to wait x seconds (with WiatSecs(x)), but I am not able to say the script to wait untile one or both participats press their keys, and after that contiuing the script. I have tried with a while loop, as in the following example, but with no success. Have you any suggestion?

AKey=KbName('A'); %accensione della luce soggetto 1
LKey=KbName('L'); %accensione della luce soggetto 1
keyFlags = zeros(256, 1);
% Set to 1 the indexed of the keys we are interested in
keyFlags([AKey, LKey]) = 1;
% Create two separate vectors for the answers, one for each
%searching for keypress
timedout = false;
pressed = 0;
%while pressed < 1;
TrialOrder = Shuffle(1 : size(TrialsTable,1));
Trial = 0;
for i= TrialOrder
    
    while ~timedout && ~pressed
        % Draw a black rectangle  that cover all the screen (background)
        Screen('FillRect', windowPtr, [0 0 0], windowRect);
        % In each cycle, import the images to be used for the current trial and convert it to a textur
        IMGcue=imread(TrialsTable.OFF{i}); % In case you want to get numbers, use () instead of {}
        IMGcueResized = imresize(IMGcue,[windowRect(4) windowRect(3)]);
        IMGtexturecueResized=Screen('MakeTexture', windowPtr, IMGcueResized);
        Screen('DrawTexture', windowPtr, IMGtexturecueResized);
        % Flip-> display the stimulus: record the moment when the stimulus
        % appear, it's needed to compute the RTs
        StimulusSecs=Screen('Flip', windowPtr);
        % Create and start the queue
        KbQueueCreate(devs(1), keyFlags); % Generating the queue
        KbQueueStart(devs(1)); % Initialising the queue
        % Close queue and Collect responses
        [pressed, firstPress, firstRelease, lastPress, lastRelease]=KbQueueCheck(devs(1));
        KbQueueStop(devs(1));    
        
        % check keyboard
        if pressed == 1 
            timedout = true;
            WaitSecs(TrialsTable.DELAY(i)/1000);
            %In each cycle import the images to be used for the current trial and convert it to a texture
            IMGoutput=imread(TrialsTable.ON{i}); 
            IMGoutputResized = imresize(IMGoutput,[windowRect(4) windowRect(3)]);
            IMGtextureoutputResized=Screen('MakeTexture', windowPtr, IMGoutputResized);
            Screen('DrawTexture', windowPtr, IMGtextureoutputResized);
            % Flip-> display the stimulus: record the moment when the
            % stimulus appear, it's needed to compute the RTs
            OutputSecs=Screen('Flip', windowPtr);
            
        end
        
    end
end

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Answer 1

T.Nikhil kumar 2023-10-26

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1749490-waiting-for-keypresses-to-continue#answer_1341256

Hello Marika,

As per my understanding you want to continue with the execution of your code after you detect one or more key presses on the device after creating and starting the queue of events.

I would suggest you to use the ‘pause’ function for this purpose. This function temporarily stops execution and waits for the user to press any key. Introduce the ‘pause’ function without any arguments after starting your queue.

Alternatively, you can try using the ‘KbQueueWait’ function, in the ‘Psych Toolbox’ itself, that waits for a key to be pressed and returns the time of the press.

Refer to the following documentation to understand more about ‘pause’ function.

https://www.mathworks.com/help/matlab/ref/pause.html

Hope this helps!