These notes recap an introduction session to using PsychToolbox, a MATLAB toolbox commonly used in conducting experiments for stimulus display and recording responses. This first introduction includes a demo of drawing text and colours, teaching concepts of windows, rects and flips.
Initializing the PsychToolbox window
When running an experiment using PsychToolbox (PTB), there are a few initial lines of code that help set up stimulus display.
screenID = max(Sreen(‘Screens’)); % Returns the screen number to display monitor Screen(‘Preference’,’SkipSyncTests’,1); % Set to 1 to skip any sync tests
[ptbWindow, winRect] = PsychImaging('OpenWindow', screenID, , , , , , 6);
[screenWidth, screenheight] = RectSize(winRect); screenCentreX = round(screenWidth/2); screenCentreY = round(screenHeight/2); flipInterval = Screen('GetFlipInterval', ptbWindow);
Drawing text (
In an experiment, text is often required when conducting an experiment, especially for instructions at the beginning, or when asking the participant for a response or informing the participant of a break. Firstly, let’s define the desired text to be shown:
text = ['Hello world!'];
To draw text, we simply use the