I’m conducting an EEG experiment with Psychopy (v1 83.04) and I’m using images as visual stimuli. I tested the image display with a photodiode and it turns out that the trigger is sent before an actual image display. I’m not sure why and whether this a problem with a code as I synchronized the trigger with a screen refresh. The biggest issue is that the delay is not constant and it’s not a multiple of 17ms (the monitor refresh is 60Hz). Additionally, I get a warning about dropped frames.
Would anyone be willing to help?
# *p_port* updates if t >= 1 and p_port.status == NOT_STARTED: # keep track of start time/frame for later p_port.tStart = t # underestimates by a little under one frame p_port.frameNStart = frameN # exact frame index p_port.status = STARTED p_port.setData(int(1)) if p_port.status == STARTED and t >= (1 + (0.5-win.monitorFramePeriod*0.75)): #most of one frame period left p_port.status = STOPPED p_port.setData(int(0))