Millisecond Forums » Millisecond Forums » Inquisit 4 » Lag to play video when repeating a trial

Lag to play video when repeating a trial

sdeanda — Thu, 12 Feb 2015 14:13:54 GMT

I've run into a strange issue when repeating trials. I've copied my code below.

I have two trials that run back-to-back (the prime trial and target trial, see below). I was successful in repeating these pairs of trials using keyboard input. However, when I incorporate a video that plays 500 ms into one of the trials, the repeated trial lags a significant amount of time (on the order of seconds) to play the video. Note that this only happens when I repeat the trial. Any help is appreciated!!

<trial prime>
/ontrialbegin = [values.itemnumber = counter.mycounter.selectedvalue]
/stimulusframes= [1 = soundWAVfile; 500 = video]
/trialduration = 3000
</trial>

<trial target>
/stimulustimes = [400 = soundWAVfile2; 800= picture]
/timeout = 3700
/recorddata = true
/inputdevice = keyboard
/validresponse = ( 19)
/responsetrial = (19, repeatprime)
</trial>

<trial repeatprime>
/stimulusframes= [1 = soundWAVfile; 500 = video]
/trialduration = 3000
/validresponse = (anyresponse)
/responsetrial = (anyresponse, repeatTarget)
</trial>

<trial repeatTarget>
/stimulustimes = [400 = soundWAVfile2; 800= picture]
/timeout = 3700
</trial>

RE: Lag to play video when repeating a trial

Dave — Thu, 12 Feb 2015 14:13:54 GMT

Great -- thanks for taking the time to update the thread!

RE: Lag to play video when repeating a trial

sdeanda — Thu, 12 Feb 2015 14:08:54 GMT

Sorry for the delayed response. I finally got a chance to go back and look at this. You were right about "stimulusframes" and "stimulustimes"! That fixed it. Thanks for the help!

RE: Lag to play video when repeating a trial

Dave — Sat, 07 Feb 2015 19:10:12 GMT

They behave absolutely identically -- or rather as expected -- for me (using arbitrary files I have plugged in, I don't have the ones you're using obviously).

What do the relevant stimulusonset columns in your data file report as onsets for the two different trials?

RE: Lag to play video when repeating a trial

sdeanda — Sat, 07 Feb 2015 19:04:20 GMT

That makes sense. But why would the prime trial run fine but not repeatprime?

RE: Lag to play video when repeating a trial

Dave — Sat, 07 Feb 2015 18:45:54 GMT

/stimulusframes= [1 = soundWAVfile; 500 = video]

You're a using *stimulusframes* here, not *stimulustimes*. I.e., you aren't displaying the video at 500 *ms* into the trial, but at 500 *frames*. Depending on your display's refresh rate, a single frame lasts between 10-20ms, i.e. the video is displayed somewhere between 5 to 10 seconds into the trial.