Pschtoolbox matlab can't control the stimulus flow - matlab

Question

I am working on a visual experiment using psychtoolbox (matlab). I was able to create the most basic experiment but I struggle with adjusting the stimulus presentation timing/order/length, etc.
I am trying to present a fixation cross continuously for 10 minutes and add text (same question) below the cross 12 times in 10 minutes in a randomized manner. Also, I want to get key responses (left or right) as answers to the question. I have to repeat this 4 times in a loop where you can take breaks of 5 minutes.
Below is the code I managed to create so far.
Could you please help?
% Clear the workspace and the screen
sca;
close all;
clear;
% Here we call some default settings for setting up Psychtoolbox
PsychDefaultSetup(2);
% Get the screen numbers
screens = Screen('Screens');
% Draw to the external screen if avaliable
screenNumber = max(screens);
% Define black and white
white = WhiteIndex(screenNumber);
black = BlackIndex(screenNumber);
grey = white / 2;
% Open an on screen window
[window, windowRect] = PsychImaging('OpenWindow', screenNumber, grey);
% Get the size of the on screen window
[screenXpixels, screenYpixels] = Screen('WindowSize', window);
% Query the frame duration
ifi = Screen('GetFlipInterval', window);
% Set up alpha-blending for smooth (anti-aliased) lines
Screen('BlendFunction', window, 'GL_SRC_ALPHA', 'GL_ONE_MINUS_SRC_ALPHA');
%----------------------------------------------------------------------
% Timing Information
%----------------------------------------------------------------------
% Interstimulus interval time in seconds and frames
isiTimeSecs = 5;
isiTimeFrames = round(isiTimeSecs / ifi);
% Numer of frames to wait before re-drawing
waitframes = 1;
%----------------------------------------------------------------------
% Keyboard information
%----------------------------------------------------------------------
% Define the keyboard keys that are listened for. We will be using the left
% and right arrow keys as response keys for the task and the escape key as
% a exit/reset key
escapeKey = KbName('ESCAPE');
leftKey = KbName('LeftArrow');
rightKey = KbName('RightArrow');
% Setup the text type for the window
Screen('TextFont', window, 'Times');
Screen('TextSize', window, 36);
% Get the centre coordinate of the window
[xCenter, yCenter] = RectCenter(windowRect);
% Here we set the size of the arms of our fixation cross
fixCrossDimPix = 40;
% Now we set the coordinates (these are all relative to zero we will let
% the drawing routine center the cross in the center of our monitor for us)
xCoords = [-fixCrossDimPix fixCrossDimPix 0 0];
yCoords = [0 0 -fixCrossDimPix fixCrossDimPix];
allCoords = [xCoords; yCoords];
% Set the line width for our fixation cross
lineWidthPix = 10;
% Draw the fixation cross in white, set it to the center of our screen and
% set good quality antialiasing
Screen('DrawLines', window, allCoords,...
lineWidthPix, white, [xCenter yCenter], 2);
% Draw text in the bottom of the screen in Times in white
Screen('TextSize', window, 40);
Screen('TextFont', window, 'Times');
DrawFormattedText(window, 'Sham (left) or Real TMS (right)?', 'center',...
screenYpixels * 0.75, white);
% Flip to the screen
Screen('Flip', window);
% Wait for a key press
KbStrokeWait;
% Clear the screen
sca;
enter code here