Timing issues about short stimuli
In my experiment, I want to present a very short stimulus (16/32/48 ms), followed by a mask. To test whether the actual presentation time is 16/32/48 ms, I used canvas.show() to log the timestamp of both the target and the mask. I calculated the presentation time by subtracting the target_timestamp from the mask_timestamp. On my own computer(refresh rate 59Hz), the calculated presentation time was about 18,34,50 ms respectively. When I tested the same program in the laboratory(refresh rate 120Hz), the calculated presentation time have a delay of about 39ms under the xpyriment backend ( like 54/70/86ms respectively) and a delay of about 28 ms under the psychopy backend. I am very confused about this problem, and I don’t know the cause of this problem. I would appreciate it if you can give me some clues to solve this problem. Looking forward to hearing from you!