Tutorial: Locating Stim (9/21)
This sample shows how any stimulus can be precisely located anywhere on the screen. This is input file is the same as the last with the exception of the Loc columns. Remember the Loc column has three variables in it: x, y and clear each separated by a comma. X and y define a single point on the screen that determines where the stimulus is placed. You can enter in actual pixel values (e.g., 200, 150 etc.) but an easier way is to use percentages (e.g., .3, .7). For example if you want to define a point that is 30% across the screen and 70% down, you would just enter .3,.7 for the x,y values. Note you can always enter 0,0 and this will automatically center the stimulus. Entering 1,1 will place it at the left, top corner.
Run the session and watch how the stimuli are located as a function of the Loc values.
In this sample the x,y point determines where the center of the stimulus is placed. If you're interested, see LOC (locating stimuli) to read more about setting location parameters.
Finally, Clear defines whether to clear the previous screen before drawing the stimulus (Clear = 1), or whether to add to it (Clear = 0) We'll look at the clear values and what they can do in the next sample.