Matthew (@mdc) and me have been exploring the issue I raised in a previous post. The problem can be summarized by the output of Matthew’s test code below:
> target_H = visual.TextStim(win=win, ori=0, > text=u'H', > font=police, > pos=[0, 0], > color=[0,0,0], colorSpace=u'rgb255', height = 0.5) > > framesMax = 200 > times = np.zeros((framesMax,)) > n = 0 > timer = core.Clock() > win.flip() > while n < framesMax: > timer.reset() > target_H.draw() > win.flip() > > times[n] = timer.getTime() > > n += 1 > > #Shutting down: > win.close() > > pylab.figure(0) > pylab.plot(np.arange(0, framesMax), times) > pylab.show() > > core.quit()
Using an NVIDIA GTX on windows, Matthew got the (normal) output below:
I ran the same code on 3 different computers running on windows (psychopy v 1 85 4). The first one has an AMD RADEON R9 200 GPU; the second an INTEL HD 4600 GPU; the third an NVIDIA GeFORCE 920M.
Output from INTEL GPU (60 Hz monitor):
Putput from RADEON (144 Hz monitor):
Same issue with the nvidia card. I wouldn’t be worried if the issue only appeared for the first or first 2 frames of an experiment. However, the timing error seems to appear every time a new object is drawn (would that mean the rt clock is off by a few milliseconds for each trial?). Could you please try to replicate, and shed light on the issue?