フィルターのクリア

Psychtoolbox checkerboard alternation error

3 ビュー (過去 30 日間)
Maheen Siddiqui
Maheen Siddiqui 2017 年 7 月 19 日
コメント済み: Walter Roberson 2017 年 7 月 19 日
Hi,
I'm new to Psychtoolbox and am using it to create a reversing checkerboard pattern on the screen. The checkerboard has been coloured such that it is more like vertical stripes rather than checks. I have two contrasting conditions a regular black/white striped pattern and then a light grey/dark grey striped pattern. At first, I was struggling with the timing aspect of things and was not able to get the screen to switch from the grey screen to black and white screen. The waitframes fixed this. However, now that I have each screen appearing for a set duration, the alternation of the pattern has stopped for each texture. Does anybody have advice on how to fix this? What is missing in my code currently that's stopping the reversing of the stripes??
Can anyone provide advice? My code is below - some very small bits of it my redundant/irrelevant, I'll clean it up later.
% Clear the workspace and the screen
sca;
close all;
clearvars;
%Screen('Preference', 'SkipSyncTests', 1);
% 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, [0 0 400 400]);
ifi = Screen('GetFlipInterval', window);
% Query the maximum priority level
topPriorityLevel = MaxPriority(window);
% Get the size of the on screen window
[screenXpixels, screenYpixels] = Screen('WindowSize', window);
%%%%%%%%%Stripe information
% Get the centre coordinate of the window
[xCenter, yCenter] = RectCenter(windowRect);
cx = (screenXpixels/2);
cy = (screenYpixels/2);
% Make a base Rect of 200 by 200 pixels
dimx = cx;
dimy = cy;
baseRect = [0 0 dimx dimy];
pos = [cx- dimx/2 ,cy - dimy/2,cx+ dimx/2 ,cy + dimy/2];
% Make the coordinates for our grid of squares
[xPos, yPos] = meshgrid(-2:0.5:2, -2:0.5:2);
% Calculate the number of squares and reshape the matrices of coordinates
% into a vector
[s1, s2] = size(xPos);
numSquares = s1 * s2;
xPos = reshape(xPos, 1, numSquares);
yPos = reshape(yPos, 1, numSquares);
% Scale the grid spacing to the size of our squares and centre
xPosLeft = xPos .* dimx + screenXpixels * 0.25;
yPosLeft = yPos .* dimy + yCenter;
xPosRight = xPos .* dimx + screenXpixels * 0.75;
yPosRight = yPos .* dimy + yCenter;
% Set the colours of each of our squares
% light grey and dark grey colours
bwColors = repmat([0.55 0.46; 0.55 0.46], 5, 5);
bwColors = bwColors(1:end-1, 1:end-1);
bwColors = reshape(bwColors, 1, numSquares);
bwColors = repmat(bwColors, 3, 1);
multiColors = repmat([0.45 0.58; 0.45 0.58], 5, 5);
multiColors = multiColors(1:end-1, 1:end-1);
multiColors = reshape( multiColors, 1, numSquares);
multiColors = repmat( multiColors, 3, 1);
%black and white colours
board3 = repmat([1 0; 1 0], 5, 5);
board3 = board3(1:end-1, 1:end-1);
board3 = reshape(board3, 1, numSquares);
board3 = repmat(board3, 3, 1);
board4 = repmat([0 1; 0 1], 5, 5);
board4 = board4(1:end-1, 1:end-1);
board4 = reshape( board4, 1, numSquares);
board4 = repmat( board4, 3, 1);
% Make our rectangle coordinates
allRectsLeft = nan(4, 3);
allRectsRight = nan(4, 3);
for i = 1:numSquares
allRectsLeft(:, i) = CenterRectOnPointd(baseRect,...
xPosLeft(i), yPosLeft(i));
allRectsRight(:, i) = CenterRectOnPointd(baseRect,...
xPosRight(i), yPosRight(i));
end
% Texture cue that determines which texture we will show
textureCue = [1 2];
% Sync us to the vertical retrace
vbl = Screen('Flip', window);
%----------------------------------------------------------------------
% Timing Information
%----------------------------------------------------------------------
% Interstimulus interval time in seconds and frames
isiTimeSecs = 10;
isiTimeFrames = round(isiTimeSecs / ifi);
% Numer of frames to wait before re-drawing
flipSecs = 12;
waitframes = round(flipSecs / ifi);
% How long should the image stay up during flicker in time and frames
imageSecs = 0.5;
imageFrames = round(imageSecs / ifi);
% Duration (in seconds) of the blanks between the images during flicker
blankSecs = 0.25;
blankFrames = round(blankSecs / ifi);
%----------------------------------------------------------------------
% Keyboard information
%----------------------------------------------------------------------
% Keybpard setup
spaceKey = KbName('space');
tabKey = KbName('tab');
escapeKey = KbName('ESCAPE');
RestrictKeysForKbCheck([spaceKey escapeKey tabKey]);
% Time we want to wait before reversing the contrast of the checkerboard
checkFlipTimeSecs = 0.5;
checkFlipTimeFrames = round(checkFlipTimeSecs / ifi);
frameCounter = 0;
%----------------------------------------------------------------------
% Experimental Loop
%----------------------------------------------------------------------
% Start screen
DrawFormattedText(window, 'Press Space To Begin', 'center', 'center', black);
Screen('Flip', window);
KbWait;
numTrials = 10;
StartTime = GetSecs;
for trial=1:numTrials
textureCue = [1 2];
tex(1)= Screen('MakeTexture',window,multiColors);
tex(2)= Screen('MakeTexture',window,bwColors);
tex2(1)=Screen('MakeTexture',window,board3);
tex2(2)=Screen('MakeTexture',window,board4);
% Draw a fixation cross for the start of the trial
Screen('FillRect', window, grey);
Screen('Flip', window);
% WaitSecs(1);
% This is our drawing loop
respMade = 0;
numFrames = 0;
frame = 0;
Priority(topPriorityLevel);
% Increment the number of frames
numFrames = numFrames + 1;
frame = frame + 1;
if frame > numPresLoopFrames
frame = 1;
end
% Decide what we are showing on this frame
showWhat = presVector(frame);
startTime = GetSecs();
limit = 12;
counter=0;
while ~KbCheck
% Draw the textures or a blank frame
frameCounter = frameCounter + 1;
if frameCounter == checkFlipTimeFrames
textureCue = fliplr(textureCue);
frameCounter = 0;
end
Screen('DrawTexture', window, tex(textureCue(1)), [],pos);
% Flip to the screen
vbl = Screen('Flip', window, vbl + (waitframes - 0.5) * ifi);
Screen('DrawTexture', window, tex2(textureCue(1)), [],pos);
% Flip to the screen
vbl = Screen('Flip', window, vbl + (waitframes - 0.5) * ifi);
% Poll the keyboard for the space key
[keyIsDown, secs, keyCode] = KbCheck(-1);
if keyCode(KbName('space')) == 1
respMade = 1;
elseif keyCode(KbName('ESCAPE')) == 1
sca;
disp('*** Experiment terminated ***');
return
end
end
end
% Bin the textures we used
Screen('Close', tex);
Screen('Close', tex2);
% Clear up and leave the building
sca;
  4 件のコメント
Maheen Siddiqui
Maheen Siddiqui 2017 年 7 月 19 日
I have figured out how to do the timing, it was as simple as setting waitframes to the correct thing. But now the flickering/alternation/reversal of the pattern has stopped. Do you have any advice?
Walter Roberson
Walter Roberson 2017 年 7 月 19 日
Yes.

サインインしてコメントする。

回答 (0 件)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by