Key presses not being logged with kbCheck

I have been mostly programming this task on the computer in my lab but I was trying to finalize and do debugging. On the lab computer, my keypresses were being logged with mostly the same code (~95%, I've made some placement changes). Now, (on my macOS laptop) it is not working. The variable keyIsDown reports no key is pressed (0) but somehow it is advancing through my loop. I have spent a couple hours trying to look at the documentation and perusing the internet, but nothing provides me to a solution. I know psychtoolbox has a neverending list of issues with functionality using macOs but Im wondering if I am just overlooking something in the code.

 while KbCheck;
     
      [keyIsDown, secs, keyCode] = KbCheck(-1); 
            if keyIsDown 
                if keyCode(accept_key) == 1  
                pchoice = 1;
                trialMatrix(t,1)= cellstr(pchoice_name{pchoice});
        WaitSecs(2);
     FlushEvents('keyDown');
    %%% some conditional statements for other keypresses follow but are not relevant to my question, so they have been removed (it's alot) %%%
    
            else keyCode(reject_key); % this is what I have been pressing
         pchoice = 2;              
      Screen('TextSize',ptb.win, 50);
         DrawFormattedText(ptb.win, balance_string ,'center', 'center', [0 0 0]); 
      Screen('Flip', ptb.win);
                      
                WaitSecs(2);
                FlushEvents('keyDown');                          
                
                cd('/Users/janedoe/Documents/Task Code'); % if choice is reject...
                     fix=imread('fixationcross.jpg');    
                     fixc= Screen('MakeTexture', ptb.win, fix);
                        
     Screen('DrawTexture', ptb.win, fixc,[],[]);
     Screen('Flip', ptb.win);
            end
            trialMatrix(t,1)= cellstr(pchoice_name{pchoice});
      
        end
    end

[Walter Roberson]

Could you be more specific about how you know that it is "advancing through my loop" ?

Note: these functions are provided by Psychtoolbox, so you should be using the support resources for that package.

[Walter Roberson]

else keyCode(reject_key);

Note that is exactly equivalent to

    else
        keyCode(reject_key);

which looks up the key code and discards it because of the semi-colon.

[Jade T]

Yes, I have posted on their community forum but they do not respond. While the keyboard input may be specific to psychtoolbox, I have a hunch that this is a general programming issue. Specifically, these key presses that I am collecting are part of a loop and when the key is pressed, it is supposed to advance to next trial ( n=30); so I mean that the loop is working, its just that the "rejectKey" input is not being saved/collected.

Also, thank you for your feedback, this was actually helpful because I didnt realize that was happening.

[Walter Roberson]

If I understand what you are saying earlier, on the Mac each time you execute

[keyIsDown, secs, keyCode] = KbCheck(-1); 

then you get back keyIsDown is 0? And if I understand correctly, you are saying that despite KeyIsDown being 0, that the code is "advancing through your loop" ?

Could you clarify what it means for your code to be "advancing through your loop" ? Is there a statement inside of the if keyIsDown section that is being executed even though your debugging appears to show that KeyIsDown is 0?

Or is the point that keyIsDown never seems to be non-zero even though you are pressing keys? Because that would be a quite different question than if keyIsDown is 0 but some statement inside the if KeyIsDown executing anyhow.

Or is the problem that keyIsDown is non-zero even though no keys have been pressed?

Some users of Laptops experienced the problem of “stuck keys”: Some keys

are always reported as “down”, so KbWait returns immediately and KbCheck

always reports keyIsDown == 1. This is often due to special function keys.

These keys or system functionality are assigned vendor specific

key codes, e.g., the status of the Laptop lid (opened/closed) could be

reported by some special keycode. Whenever the Laptop lid is open, this key

will be reported as pressed. You can work around this problem by passing

a list of keycodes to be ignored by KbCheck and KbWait. See

“help DisableKeysForKbCheck” on how to do this.

[Jade T]

Well the kb check is nested within a for loop ( this is what I mean about advancing through) so for example:

one trial contains some images and requires user input, then it should advance to the next one- also with user input. When the specific key press happens (ie reject) ...pchoice = 2 should be stored and saved, but it is not being saved. Therefore, I am not sure if its because keyIsDown is 0, therefore it will not go to the next conditional statement. I have modified my code now so that it looks like this:

while KbCheck
      end
      
      go = 0;
      while go == 0
      [keyIsDown, secs, keyCode] = KbCheck(-1);% read the current status of the keyboard; secs is the time of the key press
            if keyIsDown % keyIsDown is a variable that is a 1 if a key is pressed and 0 if no key is pressed
                if keyCode(accept_key)  %  logic test, if the value of keyCode corresponding to 'accept_key' is pressed
                pchoice = 1;
                else 
            keyCode(reject_key)
            pchoice = 2;              
                trialMatrix(t,1)= cellstr(pchoice_name{pchoice});
                end
            end
      end
   
   %------conditional if statement folows for pchoice= 1
   
    % if choice is reject...
    WaitSecs(1);
      Screen('TextSize',ptb.win, 50);
              DrawFormattedText(ptb.win, balance_string ,'center', 'center', [0 0 0]); 
      Screen('Flip', ptb.win);
       
      WaitSecs(1);
            
%             cd('/Users/jt394/Documents/Task Code');
                     fix=imread('fixationcross.jpg');    
                     fixc= Screen('MakeTexture', ptb.win, fix);
                        
     Screen('DrawTexture', ptb.win, fixc,[],[]);% double brackets signifies default drawing to center of the screen
     Screen('Flip', ptb.win);
end