Task function reference

availability: mgl 2.0
You can now use a GUI to set all of your screen parameters so that when you call initScreen everything is customized for your system. The settings will be stored across matlab sessions in a file called .mglScreenParams in your home directory. If you had been passing in a screenParams field to initScreen in your mgl program, you should convert to using mglEditScreenParams. To set the parameters you need to have mrTools installed (see Getting Started).

Start by setting your parameters:

mglEditScreenParams

This will bring up a dialog that looks like this:

This first dialog box allows you to manage all of the displays that you have for your computer. You can keep multiple different screen parameters if you have multiple displays on your computer for instance (one for each display). You may also want to keep different display settings for different uses, for example if you like to debug your code with a windowed context, then create another display parameter for the windowed context and set the displayName to say, debug. Then when you run initScreen you can select which display settings to use by passing in the displayName. For example, initScreen('debug').

In this dialog box you can add, delete or restore default settings for each display setting.

Next, you should edit the screen parameters for your desired display by selecting the display and clicking OK. You should see a dialog like this:

Here you can set all of your screen parameters (including the displayName which is how you access the settings with initScreen). You can test the settings using the “testSettings” button. The help button gives you information about all the settings. Here is a list of what the settings do:

purpose: initializes the screen
usage: myscreen = initScreen(<myscreen>,<randstate>)

This function initializes the screen by calling mglOpen, and also handles a number of different default initialization procedures such as setting up the gamma table with the correct linearization table. You should call this once at the beginning of the experiment. The variable myscreen will contain many fields associated with the status of the screen and records events like volume acquisitions and trial/segment times etc.

There are a number of parameters that will be specific to your computer/display that you can set by setting the screenParams field of myscreen to save information about your setup:

myscreen.screenParams{1} = {'yoyodyne.cns.nyu.edu',[],2,1280,1024,57,[31 23],60,1,1,[],[],[0 0]}; 
myscreen = initScreen(myscreen);

This will set parameters for your screen. The parameters in order are

• computerName
• displayName (optional–for computers with multiple displays like lcd and projector. You select which display you are working on by setting myscreen.displayname to the string stored here)
• displayNumber
• screenWidth (in pixels)
• screenHeight (in pixels)
• displayDistances (in cm)
• displaySize (in cm)
• framesPerSecond (in Hz)
• autoCloseScreen (1 to close screen at end of experiment, 0 to leave it open)
• saveData (1 to save data file, 0 not to save data file,n>1 saves a data file only if you exceed n number of volumes)
• monitorGamma (The monitor gamma to correct for if you do not have a calibration file. Macs are supposed to have a gamma of 1.8)
• calibFilename (the name of the calibration file–usually just the computer name–see below under moncalib)
• flipHV (Whether to flip the screen horizontally and/or vertically–an array of length two 0=no flip, 1 = flip)

MGL 2.0: The initScreen program looks for a file called by default mgl/task/mglScreenParams.mat which contains a cell array of computer display information parameters like the above (as long as you don't set myscreen.screenParams before calling initScreen). This way you can save a file which contains information about all the computers in your lab and always load that up rather than having each stimulus program contain all the information. You can do this by changing the name of the file that initScreen loads by setting:

screenParams{1} = {'yoyodyne.cns.nyu.edu',[],2,1280,1024,57,[31 23],60,1,1,[],'yoyodyne',[0 0]};   
screenParams{2} = {'terranova.bnf.brain.riken.jp',[],0,800,600,57,[31 23],60,1,0,[],[],[0 0]};   
save ~/Desktop/myScreenParams.mat screenParams
mglSetParam('screenParamsFilename','~/Desktop/myScreenParams.mat');

purpose: initializes the global stimulus variable name
usage: myscreen = initScreen('stimulusName',myscreen);

Note that this function, only needs to be called if you want to save the stimulus in your stim file. Since stimulus is a global variable, if you call this function, at the end of the experiment it will get the global variable with the name you specified here and save it in your stim file. If you do not need to save your stimulus variable, you do not need to call this function.

purpose: initializes a task variable
usage: [task myscreen] = initTask(task,myscreen,startSegmentCallback,screenUpdateCallback, trialResponseCallback, <startTrialCallback>, <endTrialCallback>, <startBlockCallback>)

The task variable gets set up as explained above. Here is a list of valid fields:

purpose: updates the task
usage: [task myscreen phaseNum] = updateTask(task,myscreen,phaseNum)

purpose: updates the screen
usage: [myscreen task] = tickScreen(myscreen,task);

This function calls mglFlush to update the screen when it is needed and also checks for volumes and keys etc. Called with in main loop.

Implements a staircase for control of stimulus variable values. Type 'help upDownStaircase' for details. Also see taskTemplateStaircase.m for examples of using this function.

Allows you to force a move to the next segment or the next trial:

task = jumpSegment(task) % this will end the segment and move to the next one

task = jumpSegment(task,inf) % this will end the trial and start a new trial