Millisecond Forums

Dear all,

I have a question about the stimulus onset by using script.elapsedtime.

Here is my code for a block:
<block MS>
/trials = [1=focus;2-45=noreplace(neu12, neu16........)]
</block>

I got data like this:
blockcode trialnum trialcode  trialduration  script.elapsedtime
MS             1              focus         6000               43169
MS             2              neu16       12000              46392
MS             3              neu12        8000               58288
.....

I have set trialduration for each trial (e.g., 6000 for trial.focus).
<trial focus>
/stimulustimes = [0=focus]
/trialduration = 6000
/validresponse = (noresponse)
</trial>

However, it is obvious that the script.elapsedtime was not consistent with trialduration (i.e.,46392-43162<6000).  This also happened to trial 2 (i.e. 58288-46392 !=12000). Why did this happen?
I need to record onset time of each trial. Can I trust the script.elapsedtime?

Best,
Yanyan