[solved] Present stimuli for different durations in a random order

amihai_gottlieb

Hi all,

I am trying to create an experiment in which the stimuli will be presented for different duration taken from the variable list. So, I put [duration] in the duration box in the sketchtab which I put in a loop. Indeed, now the stimuli are presented for the durations in the variable list yet i need these durations to be in a random order and not fixed to the variables in the adjacent list. Is there a way to do this in OpenSesame?

I have searched for similar questions but did not fully understand the questions or the answers sinceI have very limited coding experience.

Any help will be appreciated.
Thanks
Amihai

lvanderlinden

Hello,

One possibility is that you define at the beginning of every block a list with all possible durations:

• Append an inline_script item to your block sequence, and place something like the following code in the Prepare tab:

# Make a list with all possible duration values.
# The list should be as long as you have trials in your block:

# For example, if you want 5 different possible values for the variable
# Duration, and every value should appear twice (i.e., every block
# contains 10 trials):
lDurations = [300,400,500,600,700] * 2

# Shuffle the list:
import random
random.shuffle(lDurations)

Next, pick one duration from this list at the beginning of every trial, without replacement.

• Append an inline_script item to the beginning of your trial sequence, and place the following code in the Prepare tab:

# Get duration on the current trial:
var.duration = lDurations.pop()

The above inline_script should be placed before the sketchpad item in which you want to use the duration. You can use the square-bracket method, that is [duration], as normally.

Hope this helps!

Cheers,

Lotje

amihai_gottlieb

Dear Lotje,

I have done what you wrote and it solved my problem!
Thank you very very much.

One comment - i needed to make sure to put the lDurations function before in a preparation part before the loop.

Amihai