Collecting responses with PsychToolbox

Hello, I am trying to collect keyboard responses with PsychToolbox using KbCheck, but when I run the code the screen freezes and refuses to close. This script is intended to close all screens ONLY after keyboard input 'y' or 'n' (yes/no). I also want to collect which key response was made and the response time. Here is the code I am using to collect responses:

Screen('DrawText', window, 'XXXXX') %stimulus is drawn
[VBL stimulusOnset] = Screen('Flip', window)

acceptedKeys = [KbName('y'), KbName('n')];
responded = 0;
while responded == 0
    [tmp,KeyTime,KeyCode] = KbCheck;
    if KeyCode(acceptedKeys)
        RT =  KeyTime - stimulusOnset
        strResponse = KeyCode
        responded = 1;
    end
    % time between iterations of KbCheck loop
    WaitSecs(0.001);
end

Screen('CloseAll');

Do you have any idea why it is not responding to the correct keyboard inputs? Thank you!

Answer 1

[Matteo Lisi]

Since you have two accepted keys the command

KeyCode(acceptedKeys)

produces a vector which corresponds to a logical "true" only if all its elements are equal to 1. Try changing it to

any(KeyCode(acceptedKeys))