[open] Collecting accumulative RT across two sketchpad frames

Tilly

Can you help? I want to present two frames consecutively for different lengths of time, and allow participants to respond at any time during the two presentations. I guess I need an inline script, but don't know how to write it appropriately... Many thanks, Tilly

sebastiaan

Hi Tilly,

The script below shows how you can collect responses while two sketchpads are being presented. In general, the trick is to alternate between showing a display and polling the keyboard. The responses are stored as response1, response_time1, etc. For more details and instructions on how to use this script in your experiment, see the code comments.

Similar questions have been asked a few times before, and these discussions may be useful as well:

• http://forum.cogsci.nl/index.php?p=/discussion/232/open-recording-responses-during-and-after-a-displayed-object/p1
• http://forum.cogsci.nl/index.php?p=/discussion/143/open-how-do-i-collect-the-keyboard_response-after-a-stimulus-disappears/p1

The script may seem a bit complicated. To get some feel about how this works, I would recommend walking through one of the Python tutorials. You won't need any extreme coding skills, just a basic understanding of the syntax:

• http://osdoc.cogsci.nl/python-inline-code/about-python-inline-code/#learning

Cheers!
Sebastiaan

Update: Fixed typo

from openexp.keyboard import keyboard

# Durations for the two displays
duration1 = 1000
duration2 = 1000

# Displays are copied from sketchpads. To avoid these
# sketchpads from being shown twice (i.e. once in the 
# normal way, and once in this inline_script), you can set
# their 'Run-if' statement to 'never'.
canvas1 = self.copy_sketchpad('sketchpad1')
canvas2 = self.copy_sketchpad('sketchpad2')

# Create a keyboard object with a zero timeout to allow
# for continuous polling.
my_keyboard = keyboard(exp, timeout=0)

# Keep track of which response we are collecting, in case
# the participant responds multiple times.
response_nr = 1

# We collect at most 10 responses, and reset these 10 responses
# to 'NA' before we start collecting new responses.
max_response_nr = 10
for i in range(1, max_response_nr+1):
    exp.set('response%d' % i, 'NA')
    exp.set('response_time%d' % i, 'NA')

# Show the first canvas, and poll the keyboard for the
# specified duration.
show_time1 = canvas1.show()
while self.time() - show_time1 < duration1:
    key, time = my_keyboard.get_key()
    # If a key is pressed, store the key and the response time.
    # The response time is the time after the presentation of the
    # first display.
    if key != None and response_nr <= max_response_nr:      
        exp.set('response%d' % response_nr, key)
        exp.set('response_time%d' % response_nr, time-show_time1)
        response_nr += 1

# Show the second canvas, and poll the keyboard for the
# specified duration.       
show_time2 = canvas2.show()
while self.time() - show_time2 < duration2:
    key, time = my_keyboard.get_key()
    # If a key is pressed, store the key and the response time.
    # The response time is the time after the presentation of the
    # first display.
    if key != None and response_nr <= max_response_nr:      
        exp.set('response%d' % response_nr, key)
        exp.set('response_time%d' % response_nr, time-show_time1)
        response_nr += 1        

Tilly

Hi Sebastiaan,
Thank you so much for all your help with this - will give it a go!
BW, Tilly

filo

I think there is a typo in this script. second while loop should compare with "duration2" not "duration1".

sebastiaan

Good spot @filo!