Sending out a marker on key-press

JJT

Hi!

I have the following snippet of code:

experiment.clock.reset_stopwatch()
key, rt = experiment.keyboard.wait(keys=[left_resp,
                                         right_resp],
                                   duration=duration_stimulus)
experiment.clock.wait(duration_stimulus - interval_tone - experiment.clock.stopwatch_time)

What I want is to send out a marker, at the time that a response (keypress) is made. However, the duration of the stimulus is fixed (1000ms), so sending a marker after the keyboard.wait function is not possible! Do you have an idea how to do this?

fladd

I think the easiest way to do this is to simply reduce your waiting time for the response by 1 or 2 ms:

experiment.clock.reset_stopwatch()
key, rt = experiment.keyboard.wait(keys=[left_resp,
                                         right_resp],
                                   duration=duration_stimulus - 2)
marker.send(1)
experiment.clock.wait(duration_stimulus - experiment.clock.stopwatch_time)

If this is not an option, you could also create your own wait loop that uses the keyboard check method continuously:

rt = None
experiment.clock.reset_stopwatch()

while experiment.clock.stopwatch_time < duration_stimulus:
    key = experiment.keyboard.check(keys=[left_resp,
                                          right_resp])
    if rt is None and key is not None:
        rt = experiment.clock.stopwatch_time

JJT

Hi,

Thanks, eventually it worked out even without the "duration_stimulus - 2". It sends a marker on key-press automatically. The following is the code now?

experiment.clock.reset_stopwatch()
key, rt = experiment.keyboard.wait(keys=[left_resp,
                                         right_resp],
                                   duration=duration_stimulus)

if key is not None:
    marker.send(36, duration=5)  # Key press marker