How do I program a selective Key Press?

I'm trying to program an experiment that advances if a certain key is pressed. I can't figure out how to do this however, and the trial advances when any key is pressed. I have spent so much time comparing my code to other people's and I can't figure out what is making mine function differently. Please help!

%%Set up keyboard
% Make KbName use shared name mapping of keys between PC and Mac
KbName('UnifyKeyNames');
space_key = KbName('space');
z_key = KbName('z');
m_key = KbName('m');
q_key = KbName('q');

% Lets write three lines of text, the first and second right after one
% another, and the third with a line space in between. To add line spaces
% we use the special characters "\n"
line1 = 'Are you ready to begin the experiment?';
line2 = '\n (press the space bar to continue)';

% Draw all the text in one go
Screen('TextSize', window, 70);
DrawFormattedText(window, [line1 line2],...
    'center', screenYpixels * 0.25, white);

      while 1
          [~, ~, key] = KbCheck;
         if strcmp(KbName(key),'space')
             break
         else

         end
      end

% Clear the screen
sca;

[Robert Fennis]

I don't know if a keyboard press is the best way to go but isn't using a GUI much easier? Just make a huge button that you can click on

[Konark Kelaiya]

Well keypressfcn of UI will do all this, even you don't need to create a GUI. Only create dummy figure with visibility "off" and use keypressfcn callback to complete your task.

Otherwise MATLAB is not the right candidate for Key press functions. you have to create a big function to do all jobs like thread / pause / polling for 5/10 sec and if no activity from keyboard-> assign error.

you can check this link

http://in.mathworks.com/matlabcentral/answers/5259-how-to-simulate-keyboard-key-inputs?s_tid=answers_rc1-2_p2

however it use fundamental of Java in MATLAB

[Geoff Hayes]

Marie - please clarify where in your code the "trial advancement" is occurring. Your code writes out a line prompting the user to press the spacebar to continue, so presumably that happens and so the condition

 strcmp(KbName(key),'space')

is true and so the break is called and the while loop is exited. Are you saying that if the user presses any key other than the space bar, then the above condition is still somehow true and the trial "advances" (i.e. the while loop terminates)?