how to set answering time window that awaits specific keypresses as response in MATLAB 2011b?

I am trying to write this task that presents an image and awaits the participant to answer by pressing eighter left arrow key or right arrow key. answering time is limited and if the time passes the next image will be presented. I am using MATLAB 2011b for some reasons.

pseudo code would be like:

function = pushbutton_callback()
    if leftArrow 
        result = left;
    else
        result = right
    end
    
    set(gcf, 'keypressFcn', @pushbutton_callback)
    while trials < 60
        presentImage();
        if keypressed
            continue
        elseif timer > 2 & keypressed = false
            result = null
            continue
        end
    end
        

Answer 1

[Jan]

% [TESTED in R2009a]
function test

FigH   = figure('KeyPressFcn', @KeyPressed);
TimerH = timer('TimerFcn', @(TimerH, EventData) uiresume(FigH), ...
               'ExecutionMode', 'SingleShot');

for k = 1:60
   % presentImage();
   
   set(FigH, 'UserData', 0);  % Set default key
   
   % Wait for 2 seconds or until key was pressed:
   startat(TimerH, clock + [0,0,0,0,0,2]);  % Overflow caught smartly
   uiwait(FigH);
   stop(TimerH);       % Ignore further timeout
   
   if ~ishandle(FigH)  % catch deleted figure:
      disp('Figure was deleted.');
      break;
   end
   
   % Check if a key was pressed:
   UD = get(FigH, 'UserData');
   switch double(UD)
      case 28
         disp('left arrow')
      case 29
         disp('right arrow')
      case 0
         disp('Too slow');
   end
end

end

function KeyPressed(FigH, EventData)
C = get(FigH, 'CurrentCharacter');
set(FigH, 'UserData', C);
uiresume(FigH);
end

With modern Matlab versions, use in KeyPressed():

c = EventData.Key;

and

set(FigH, 'UserData', 'noKey');
...
UD = get(FigH, 'UserData');
switch UD
    case 'leftarrow'
        ...
    case 'rightarrow'
        ...
    case 'noKey'
end

[babak khalilvandian]

this helped me a lot. THANK YOU!