Millisecond Forums

Awesome- thank you so much!

Yes, of course that's possible. /position, /hposition and /vposition attributes accept expressions / can use <list> or <counter> elements. The approach you need to go for depends on what exactly you want to do: "Randomizing" screen position can mean a number of different things.

Ah, okay. If I wanted the images in the same positions on the screen, but just on different sides depending on the subject, would I need to make separate trials (e.g. a,b in one, b,a in the other)?

No, not necessarily. You can do stuff like<block myblock>
/ trials = [1-4=mytrial]
</block>

<trial mytrial>
/ stimulusframes = [1=a,b]
/ validresponse = (a,b)
/ inputdevice = mouse
</trial>

<text a>
/ items = ("A")
/ hposition = list.hpositionlist.nextvalue
/ vposition = 50%
</text>

<text b>
/ items = ("B")
/ hposition = list.hpositionlist.nextvalue
/ vposition = 50%
</text>

<list hpositionlist>
/ items = (40%,60%)
/ selectionmode = random
/ selectionrate = always
</list>
or any number of more complex variations thereof. It all depends on what you want to achieve.

ah, okay, that is super helpful! thank you so much- I think I've figured most of it out.

See the "How to present stimulus pairs" topic in the documentation.