Pschtoolbox matlab can't control the stimulus flow

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