<list answers1>
/ items = (30, 38, 38, 30, 38, 38, 30, 30, 30...)
/ selectionmode = list.answers1.currentindex</list>
This does not make sense, because is circular: You are instructing the list to select the item # currently selected by the list itself.
> trial.enc1.currentindex
There is no such thing as a <trial>'s current index.
The list needs to be locked to the *stimulus* element it pertains to as in the example I linked:
<text mytext>
/ items = ("A1", "A2", "B1", "B2")
</text>
* 30 = scancode for "A"-key / 48 = scancode for "B"-key *
<list cresp>
/ items = (30, 30, 48, 48)
/ selectionmode = text.mytext.currentindex
</list>
In your case, based on your initial post, you'll want to lock the list to <picture scenes1>
as in
<list answers1>
/ items = (30, 38, 38, 30, 38, 38, 30, 30, 30...)
/ selectionmode = picture.scenes1.currentindex
</list>