Millisecond Forums

The code is somewhat incomplete and thus hard to make sense of. What you should do (and it looks like you already do some of it, how much I can't be sure of):

#1: In <trial targetpresent8> store your stimuli's x and y positions in global variables (<values> entries). Your stimuli should use those values in their respective /hposition and /vposition attributes.

<trial targetpresent8>
...
/ontrialbegin = [values.distractor_x1 = expressions.xcenter + list.x_coordinates_pictures.nextvalue]
/ontrialbegin = [values.distractor_y1 = expressions.ycenter + list.y_coordinates_pictures.nextvalue]
...
/stimulusframes = [1 = fixation, distractor1, distractor2, distractor3, distractor4, distractor5, distractor6, distractor7, target]
...
/branch = [trial.targetlocation8]
</trial>

with 

<picture distractor1>
...
/ hposition = values.distractor_x1
/ vposition = values.distractor_y1
...
</picture>

and so forth. Importantly, you only do that in the "1st screen" trial.

#2: You'll want to set up separate "targetlocation" trials for different numbers of distractors as well as present or absent. I.e., <trial targetlocation8>, <trial targetlocation7>, and so forth. /branch to the appropriate trial from the "targetpresent" or "targetabsent" trial.

#3: Then all you need is to have the respective "targetlocation" trial display the same stimuli again:

<trial targetlocation8>
...
/stimulusframes = [1 = targetlocationinstructions, distractor1, distractor2, distractor3, distractor4, distractor5, distractor6, distractor7, target]
...
</trial>

The array will be identical to the one displayed in the 1st screen.

Hi Dave,

(So sorry for getting replying this late. Got called away from work for the past 2 weeks)

Thanks so much for your reply though! I have that bit sorted for now. The stimuli did have their positions logged (didn't want to chuck in too much here) but it was the issue of having it come up exactly the same in the next page/frame. Thanks again! :) 

On another related code, I've set up another similar paradigm but instead of asking people to identify the location of the targets, people will simply view the array and press two keys (yes or no) to indicate if they saw the target.

Basically, each trial follows this sequence : "Ready" ---> Fixation ---> Array of images ---> Array stays on until people respond "yes" or "no" to having seen the target

I have got the program running and data is recorded just fine as well but I do get this message at the end of it :

The element 'mixedcues' in branch expression 'mixedcues' is the wrong element type.

I belive it refers to this bit of code here:

<trial ready>
/ontrialbegin = [list.x_coordinates_pictures.reset()]
/ontrialbegin = [values.stimulilocations = ""; values.target = ""; values.trialtype = ""]
/ontrialbegin = [values.hit = 0; values.miss = 0; values.FA = 0; values.CR = 0]
/stimulusframes = [1 = ready]
/timeout = values.readyduration
/recorddata = false
/errormessage = false
/branch = [trial.fixation]
</trial>

<trial fixation>
/stimulusframes = [1 = fixation]
/timeout = values.fixationduration
/recorddata = false
/errormessage = false
/branch = [block.mixedcues]
</trial>


<block mixedcues>
/preinstructions = (cue)
/skip = [values.blockedcues == true]
/stop = [values.count_sequence == values.trialnumber]
/onblockbegin = [values.count_sequence = 0]
/onblockbegin = [values.countblocks += 0]
/trials = [1-16 = noreplace(targetpresent4distractor1, targetpresent6distractor1, targetpresent8distractor1, targetabsent4distractor1, targetabsent6distractor1, targetabsent8distractor1,
                                          targetpresent4distractor2, targetpresent6distractor2, targetpresent8distractor2, targetabsent4distractor2, targetabsent6distractor2, targetabsent8distractor2,
                                          targetpresent4distractor3, targetpresent6distractor3, targetpresent8distractor3, targetabsent4distractor3, targetabsent6distractor3, targetabsent8distractor3)]
</block>




The codes in blue are the different 18 trial types/specific stimuli arrangements that the task goes through.

Could you let me know what I've done wrong for the error to come up?

Thanks! :)

The reason for the message is this: /branches need to take place at the same "level", i.e., a <trial> may /branch to another <trial>, but not to a <block>. Conversely, a <block> may /branch to another <block>, but not to a <trial>.

<trial fixation>
/stimulusframes = [1 = fixation]
/timeout = values.fixationduration
/recorddata = false
/errormessage = false
/branch = [block.mixedcues]
</trial>

You can't /branch to a <block> from a <trial>, which is what the above aims to do. The /branch needs to either reside at the <block>-level, or you need to /branch to a <trial> instead of a <block>.

Got it! Thanks so much for your help Dave. :)