Thread Tools  
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Timing Accuracy with Auditory Stroop Task, Posted October 15th, 2014 #1
Hi,

I have created an auditory stroop task on SuperLab 4.5, but I am having problems with timing accuracy.

We have 14 blocks of a condition, each block has one trial, and each trial is made up of one event created as a stimulus list with 12 different audio files that will play at random. We set it so that each audio file would end after a time limit of 1500ms. This would make each block, 18 seconds theoretically. The events are paired with a pitch-response que to play simultaneously with the audio.

We created a presentation that would last 6:06s (excluding scan triggers), however, in running the presentation without selecting any responses, the timing was 8:72s. When responses were selected, the timing was even more varied between each stimuli.

I have attached the .sl4 file of the presentation in question. Is there a way to get the timing accurate? I tried applying the trial synchronization feature in the Trial Editor but that just made each event 18 seconds.

Thank you very much for your time.
Reply With Quote
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Posted October 15th, 2014 #2
Hi,

I have attached my presentation as an Experiment Package. Disregard first .sl4 attachment
Reply With Quote
Hisham
Founder
 
Join Date: Aug 2006
Location: San Pedro, CA
Hisham is on a distinguished road Posts: 1,193
Posted October 15th, 2014 #3
I have downloaded your experiment. Have you seen the page Synchronizing Trial Presentation With fMRI Scanner?

Also in your experiment, the “Pitch-response cue” event does not have a time limit; a participant can take as long as she wants to reply. Is that on purpose? Typical experiments that involve a scanner trigger will have a time limit to make sure that the trial is complete before the next scan trigger comes in.
Reply With Quote
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Posted October 17th, 2014 #4
We want to know the response rate in addition to seeing if they responded correctly or not. Each pitch, theoretically should play for 1500ms, and the participant has that much time to respond. Would I need to link the audio stimulus (congruent/incongruent events) with the visual pitch-response que and set both to 1500ms?

I read that article but did not find it helpful. For the superlab setup do i need to create a separate event just for scanner trigger input and then link it with each trial? I also tried method 2 and used the trial end option, and had it so that each trial would end after 18000ms, but that just made each event play for 18 seconds.

Another thing; In the manual, it mentioned that in order to present a sound with a visual at the same time, the sound event needed to come first and the text file second. The sound file input needed to be on "Immediately after the event is presented" and stimulus "Wait for sound to finish playing" setting needed to be off.I tested this out and I set a time limit for the pitch-response que but no answers were saved in the data file.

The pitch-response que is only meant to be shown simultaneously with the audio, as a reminder to respond to the pitch. So the participant is responding to the audio.

Our Scanner's TR rate is 720ms, which is shorter than each stimuli alone, so I'm not exactly sure how to have it all sync if the trial needs to end before the next trigger.

I apologize this is my first time using Superlab so it has been a bit of a learning curve.
Reply With Quote
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Posted October 17th, 2014 #5
I am also reading that using the time limit option is not the best idea. The reason we had it in the first place was because we don't want to move to the next event until the time limit is up, regardless if the participant responded correctly or not.
Reply With Quote
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Posted October 17th, 2014 #6
Thanks Hisham for helping me resolve this via phone and screen sharing. Your time was greatly appreciated!
Reply With Quote
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Unresolved issue Auditory Stroop Paradigm, Posted October 21st, 2014 #7
Hi,

I spoke with Hisham last Friday in regards to the auditory stroop, to which he was very helpful - however, the suggestions made did not resolve the issue after getting off the phone.

You suggested to use the trial pacing option for each of our trials by setting it to 1500ms, and it's events (auditory stimulus) to 1350ms, because the event time limit needs to be shorter than the trial time.

After I spoke with you and ran the experiment (without selecting responses), The average time for each event was about 1550ms, still over, but much closer to where we want it to be. When I ran the experiment and made a response, once again the time was very variable.

It doesn't make sense as to why the time for each event is still going over, if we are using the trial pacing option. Does it have something to do with using the stimulus list?

Theoretically, the set up should have worked, but when it comes to responses, it still is not matching up.
Reply With Quote
jesstalero
Junior Member
 
Join Date: Oct 2014
jesstalero is on a distinguished road Posts: 7
Unresolved issue Auditory Stroop Paradigm, Posted October 21st, 2014 #8
For your convenience,

I have attached a revision of my stroop presentation as well as a pdf of the data file with cumulative time broken down into individual event times.

We are doing a scan today and we hope to get this running correctly very soon.

Thank you
Reply With Quote
Hisham
Founder
 
Join Date: Aug 2006
Location: San Pedro, CA
Hisham is on a distinguished road Posts: 1,193
Posted October 21st, 2014 #9
Sorry that I wasn’t in the office in the morning to take your call. Kelly updated me, that what you are trying to do should work with the latest version of SuperLab, v5.0.3.
Reply With Quote
Thread Tools
Posting Rules
Forum Jump:
© Copyright Cedrus Corporation, 1991-2014.
All times are GMT -7. The time now is 12:39 PM.