waitKeys in an if condition stalls the experiment even when the condition is not TRUE

Coding
1

In our experiment, we have 4 separate blocks. What I had in mind was that the default waiting time between the blocks is 60s. However, in case the participant needs a longer rest, there would be an option to press space to prolong the rest and the rest will go on until they press space twice. The space key functionality works perfectly. But when nothing is pressed the next interval does not automatically start after 60s. I think the issue is in the way waitKeys works but I don’t exactly know how to debug it.

while core.getTime() - block_end_time < 60.0:
            keyPressList = kb.getKeys(keyList = None, waitRelease = False, clear = False)
            keyPressNamesList = [key.name for key in keyPressList if len(keyPressList) > 0]
            if 'space' in keyPressNamesList:
                el_tracker.sendMessage('SPACE pressed')
                msg = 'Vous pouvez, si vous voulez, reposer vos yeux.\n' + \
                    '\nFaites attention à ne pas bouger.\n' + \
                    '\nAppuyez deux fois sur ESPACE, quand vous prêt.e, pour passer à la suite.'
                show_msg(win, msg)
                win.flip()
                event.waitKeys(keyList=['space'])
                el_tracker.sendMessage('End of prolonged inter-block rest.')
                break
            core.wait(0.1)  # Sleep to reduce CPU load
2

waitKeys isn’t relevant unless the space key is pressed at least once, so that shouldn’t be the issue if this is happening when you don’t press any keys at all. If that’s the problem, then it’s the while loop itself that’s not working as expected.

To debug it, I would put print(str(core.getTime()-block_end_time)) in your code right after core.wait(0.1). If it’s working as intended, then you should see a series of numbers increasing by .1 (ish) every time up to 60.0. Otherwise, it will hopefully tell you something about why the while loop isn’t ending when expected.

3

I don’t think core is a clock.

4

It’s deprecated but the function still works, it’s the global timer from the start of the experiment.

5

Thanks for the answers.
I will put the answer below just in case it is useful for someone:
Indeed the issue was not the waitKeys in the loop but two other things where contributing to the issue:

  1. Just before the loop, a message was prompted on the screen (not included in the above code snipet). I had activated the event.waitKeys() option for that message meaning that nothing was happening unless a key (any key not just space) was pressed. Therefore, the while loop was not even running before I corrected that!
  2. For the entire code whenever I needed the relative timing I had used time.perf_counter() including for defining block_end_time (again not included in the above code snipet). This function prints arbitrary times which are good for comparison but definitly are not good when making comparisons to the timing printed by core.getTime(). Therefore the while loop had no logic subtracting two different timing systems! by changing the condition to “while time.perf_counter() - block_end_time < 60.0:” everything runs smoothly now!