Key presses are not recording properly

Online experiments
1

If this template helps then use it. If not then just delete and start from scratch.

OS (e.g. Win10): MacOS Big Sur
PsychoPy version (e.g. 1.84.x): 2020.2.10
Standard Standalone? (y/n) If not then what?: y
What are you trying to achieve?:
I am trying to collect responses in my experiment. Our visual stimulus is presented as a sequence of images so it is perceived as a drifting grating. This means in the routine each image is only presented for a small fraction of a second (0.1s). As the images are being presented I am collecting a keyboard response. Everything seems to be working, but I have noticed that not every response is being recorded. The way I verified this is to have every keypress print out and I have noticed that sometimes I have to press the key 2-3 times really fast before the press is recorded. Is this the case because the time window is so short (0.1s). If so is there a way to get around this?

2

Presenting multiple images in rapid succession can indeed cause performance issues: it can take a non-negligible amount of time to load images from disk and apply them to a stimulus.

Is there a reason why you aren’t able to use the grating stimulus to achieve what you want, rather than presenting a series of pre-generated images? In fact this (presenting dynamically controllable gratings) was the initial impetus for Jon Peirce to create PsychoPy in the first place way back in the day - this was one of its first features.

3

use event.getKeys() in code or remove the option to clear the keyboard buffer in your keyboard response.

Or present all your images in a single routine so your keyboard response can span the whole sequence.

4

Our experiment will be presented in pavlovia and so we have to use pre-generated images rather than the grating stimulus built into builder.

5

I am fairly new to PsychoPy I am not sure how I would use event.getKeys() in code and if this would be compatible with Pavlovia. Also is there a way to clear the keyboard using the keyboard component?

All the images are currently presented in one routine that loops through a CSV file with the names of the images. Since this is the case the timing of the image and the timing of the keyboard have to be the same.

6

Ahh. I know ways to optimise a rapid image presentation task like this to run locally using Python, but am not familiar enough with the online environment to venture into offering advice there.

7

One the keyboard component, there is a checkbox called discard previous. I don’t think you want it ticked.

However, here’s some sample Each Frame code from one of my experiments, which you can try out here: https://run.pavlovia.org/Wake/change-detection-rsvp:

if drawn == nObjects*2+2:
    continueRoutine=False
elif drawn > nObjects+1:
    if hidden==1 and myClock.getTime() > gapTime:
        pic[drawn-nObjects-2].setAutoDraw(True)
        print('waxon',drawn,'t',t)
        hidden=0
        myClock.reset()
    elif hidden==0 and myClock.getTime() > frameSpeed:
        pic[drawn-nObjects-2].setAutoDraw(False)
        print('waxoff',drawn,'t',t)
        drawn+=1
        hidden=1
        myClock.reset()
elif drawn == nObjects+1:
    if myClock.getTime() > maskTime:
        imageNoise.setAutoDraw(False)
        drawn+=1
        hidden=1
        myClock.reset()
elif drawn == nObjects:
    imageNoise.setAutoDraw(True)
    drawn+=1
    print('drawn2',drawn,'t',t)
    if thisCondition[1]==1:
        shuffle(thisOrder)
        pic[thisOrder[0]].fillColor=colours[thisOrder[1]][1]
        pic[thisOrder[1]].fillColor=colours[thisOrder[0]][1]
        pic[thisOrder[0]].lineColor=colours[thisOrder[1]][1]
        pic[thisOrder[1]].lineColor=colours[thisOrder[0]][1]
        thisExp.addData('Swap1',thisOrder[0])
        thisExp.addData('Swap2',thisOrder[1])
        print('Swap1',thisOrder[0])
        print('Swap2',thisOrder[1])
    if thisCondition[0]==1:
        shuffle(thisOrder)
    else:
        thisOrder=[0,1,2,3,4]
    print('Order',thisOrder)
    thisExp.addData('Order',thisOrder)
    myClock.reset()
elif hidden==1 and myClock.getTime() > gapTime:
    pic[drawn].setAutoDraw(True)
    print('waxon',drawn,'t',t)
    hidden=0
    myClock.reset()
elif hidden==0 and myClock.getTime() > frameSpeed:
    pic[drawn].setAutoDraw(False)
    print('waxoff',drawn,'t',t)
    drawn+=1
    hidden=1
    myClock.reset()

This uses an array of polygon objects created in Begin Routine

shuffle(shapes)
shuffle(colours)
pic=[]
for Idx in range(nObjects):
        pic.append(visual.ShapeStim(
        win=win,
        fillColor=colours[Idx][1],
        lineColor=colours[Idx][1],
        vertices=shapes[Idx],
        pos = (0,0),
        size=scale
        ))

Alternatively, you could have load the images into a list before the trial using my interleaved list principle and then .setImage at intervals in the Each Frame code.