[solved] Collecting number of keypresses in a fixed amount of time

alberhernandez

Hi, i'm making an experiment and i want to collect the number of times that the subject press the key "1" in 8000ms.
That's the important part.

If possible (it's secondary), i want to collect also the times between responses, or the amount of time if "1" is being holded (it would be interesting for a graphic, later).

It seems simple, but i'm new with this software and i would be very grateful if somebody can help me, because we're a little rushed.

Thanks, thank you for make OpenSesame, great software.

Edwin

Hi!

In theory, you could do this using the GUI, but you'd end up with massive data files! The easiest solution would probably be to use the following code in an inline_script item:

# import the keyboard class, to be able to
# poll the keyboard
from openexp.keyboard import keyboard
# import numpy, which we will use to do
# some calculations with
import numpy

# initialize a keyboard instance
kb = keyboard(exp, keylist=['1'], timeout=10)

# create an empty list, to store the keypress
# times in (so we can use those later)
presstimes = []

# let the user smash your keyboard for 8 seconds!
t0 = self.time()
while self.time() - t0 < 8000:
    # wait for a keypress
    keypress, presstime = kb.get_key()
    # add the press time to our list
    if keypress:
        presstimes.append(presstime)

# convert the list of keypresses to a numpy
# array of keypresses, to make calculations
# easier to do
presstimes = numpy.array(presstimes)

# after the frenzy, convert the keypress times to
# reactiontimes, by calculating the difference
# between each presstime (using numpy.diff)
intresptimes = numpy.diff(presstimes)

# calculate the mean and standard deviation
# of the inter-press times
M = numpy.mean(intresptimes)
SD = numpy.std(intresptimes)

# some more descriptives: the amount of
# presses and the standard error of the mean
N = len(intresptimes)
SEM = SD / (N**0.5)

# save the variables so that they can be used
# in OpenSesame's GUI
exp.set("Nipt", N)
exp.set("Mipt", M)
exp.set("SDipt", SD)
exp.set("SEMipt", SEM)

Keeping track of how long the button was down, is not possible in this way. You'll have to directly use either PyGame or PsychoPy to do so.

Good luck!

alberhernandez

Thank you very much Edwin!

I'm experiencing this problem when trying to run the experiment with the given code:

Error while executing inline script

phase: run
item: inline_script
line: 9
exception message: __init__() takes at least 2 arguments (3 given)
exception type: TypeError

Edwin

My apologies, that's due to a silly mistake (forgot to pass exp to the keyboard!). I've edited my previous post, so it should work now.

alberhernandez

Thank you very much. It works like a charm.