Hi all, I have been coding an experiment using the psychopy API to manage my display, present stimuli, etc. As I’m inexperienced with the API, I want to ask a couple of questions about RT measurement.
One: I want to confirm that my procedure will measure RT correctly. First I prepare the stimulus (or make a list of stimuli). Then I draw the stimulus(or list of stimuli), followed by a win.flip and an event.waitkeys. The RT is then the timestamp of the event.waitKeys minus core.getTime() right after the win.flip. Below is a sample take from my experiment code (and simplified to be self-contained):
from psychopy import visual, core exp_window = visual.Window(color=(-1, -1, -1), fullscr=False) stim = visual.TextStim(win=exp_window, text=text, font="Arial", height=height, wrapWidth=wrapWidth) stim.draw() win.flip(clearBuffer=True) t0 = core.getTime() resp = event.waitKeys(timeStamped=True) RT = resp - t0
Two: I am wondering whether my monitor refresh rate will have a large effect on my RT measurement from the start of the stimulus presentation to the response time. I am really most interested in this, a little bit of variability in the amount of time it takes for the stimulus to be initially presented isn’t a big deal as long as the RT measurement from that point onwards is good. As I understand it, the procedure I pasted above should get the initial time (t0) right after the win flip succeeds. Does that mean that my t0 will start from after the screen refresh, and thus my RT measurement will be relatively independent from refresh rate?
Thanks very much for your time and fantastic python package!