Hi all,

I am trying to program a visual selective attention task wherein participants are presented with a pair of stimuli (e.g., B 9) and are instructed to hit a specified key according to specific rules (if there is an odd number on the left, press the left arrow; if there is an even number on the right, press the right arrow; if there are neither, press the down arrow; if there are both, press the up arrow). The attached syntax is for the first practice trial whereby 16 pairs of stimuli are presented for 2 seconds each.

I am specifically having difficulty with: 1) assigning what response is correct to each pair of stimuli, and 2) for some reason the pairs of stimuli are overlapping (which can be seen if you run the attached code).

Any input will be greatly appreciated. Granted, I will likely be coming back to ask more questions down the road.

Syntax (note: spaces between the stimuli are because I have yet to find a way to meet the specifications by using syntactical arguments [i.e., 3x9mm in size and 124mm apart]):

<text coffee>
/items = ("coffee                                                            ")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice1>
/items = ("5                              B")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice2>
/items = ("J                              C")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice3>
/items = ("G                              K")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice4>
/items = ("R                              D")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice5>
/items = ("8                              B")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice6>
/items = ("B                              4")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice7>
/items = ("D                              G")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice8>
/items = ("W                              I")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice9>
/items = ("1                              F")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice10>
/items = ("D                              4")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice11>
/items = ("6                              A")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice12>
/items = ("P                              9")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice13>
/items = ("X                              B")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice14>
/items = ("3                              C")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice15>
/items = ("T                              9")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<text practice16>
/items = ("2                              Z")
/fontstyle = ("Arial", 40pt, true)
/txcolor = (0, 0, 0)
</text>

<trial show_coffee>
/stimulustimes = [0=coffee]
/timeout = 2000
/posttrialpause = 2000
</trial>

<trial show_practiceset1>
/stimulustimes = [0=practice1; 2000=practice2; 4000=practice3; 6000=practice4; 8000=practice5;
            10000=practice6; 12000=practice7; 14000=practice8; 16000=practice9; 18000=practice10;
            20000=practice11; 22000=practice12; 24000=practice13; 26000=practice14; 28000=practice15; 30000=practice16]
/timeout = 32000
/posttrialpause = 2000
</trial>

<block practice>
/trials = [1=trial.show_coffee; 2=trial.show_practiceset1]
</block>

<expt cavat>
/blocks = [1=block.practice]
</expt>

<trial show_practiceset1>
/stimulustimes = [0=practice1; 2000=practice2; 4000=practice3; 6000=practice4; 8000=practice5;
            10000=practice6; 12000=practice7; 14000=practice8; 16000=practice9; 18000=practice10;
            20000=practice11; 22000=practice12; 24000=practice13; 26000=practice14; 28000=practice15; 30000=practice16]
/timeout = 32000
/posttrialpause = 2000
</trial>

This does not make sense. You need to specify and run *multiple* <trial> elements: One trial per type of stimulus you want to collect a response to.

> participants are presented with a pair of stimuli (e.g., B 9) and are instructed to hit a specified key according to specific rules
> (if there is an odd number on the left, press the left arrow; if there is an even number on the right, press the right arrow;
> if there are neither, press the down arrow; if there are both, press the up arrow).

You need four <trial> elements: <trial odd_left>, <trial even_right>, <trial neither>, <trial both>.

<trial odd_left> presents the stimuli where an odd number is on the left. You specify the left arrow as the <trial>'s /correctresponse
<trial even_right> presents the stimuli where an even number is on the right. You specify the right arrow as its /correctresponse.
(and so forth)

<trial odd_left>
/ stimulusframes = [1=odd_left_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (203)
...
</trial>

<trial even_right>
/ stimulusframes = [1=even_right_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (205)
...
</trial>

<trial neither>
/ stimulusframes = [1=neither_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (208)
...
</trial>

<trial both>
/ stimulusframes = [1=both_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (200)
...
</trial>

<block practice>
/trials = [1-16 = noreplace(odd_left, even_right, both, neither)]
</block>

with

<text odd_left_stims> containing all items where an odd number is on the left,
<text even_right> all items with an even number on the right, and so forth.

If you wish to administer items and/or trials in a specific sequence, use /select = sequence in the <text> elements and specify the exact order of trials in the <block>'s /trials attribute.

<trial show_practiceset1>
/stimulustimes = [0=practice1; 2000=practice2; 4000=practice3; 6000=practice4; 8000=practice5;
            10000=practice6; 12000=practice7; 14000=practice8; 16000=practice9; 18000=practice10;
            20000=practice11; 22000=practice12; 24000=practice13; 26000=practice14; 28000=practice15; 30000=practice16]
/timeout = 32000
/posttrialpause = 2000
</trial>

This does not make sense. You need to specify and run *multiple* <trial> elements: One trial per type of stimulus you want to collect a response to.

> participants are presented with a pair of stimuli (e.g., B 9) and are instructed to hit a specified key according to specific rules
> (if there is an odd number on the left, press the left arrow; if there is an even number on the right, press the right arrow;
> if there are neither, press the down arrow; if there are both, press the up arrow).

You need four <trial> elements: <trial odd_left>, <trial even_right>, <trial neither>, <trial both>.

<trial odd_left> presents the stimuli where an odd number is on the left. You specify the left arrow as the <trial>'s /correctresponse
<trial even_right> presents the stimuli where an even number is on the right. You specify the right arrow as its /correctresponse.
(and so forth)

<trial odd_left>
/ stimulusframes = [1=odd_left_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (203)
...
</trial>

<trial even_right>
/ stimulusframes = [1=even_right_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (205)
...
</trial>

<trial neither>
/ stimulusframes = [1=neither_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (208)
...
</trial>

<trial both>
/ stimulusframes = [1=both_stims]
/ validresponse = (203,205,200,208)
/ correctresponse = (200)
...
</trial>

<block practice>
/trials = [1-16 = noreplace(odd_left, even_right, both, neither)]
</block>

with

<text odd_left_stims> containing all items where an odd number is on the left,
<text even_right> all items with an even number on the right, and so forth.

If you wish to administer items and/or trials in a specific sequence, use /select = sequence in the <text> elements and specify the exact order of trials in the <block>'s /trials attribute.

Hi Dave,

I cannot figure out how to present the stimuli in the order I want. Should I just make <trial> element for each item (e.g., <trial practice1>, <trial practice2>, etc.) so I can get them in the right order? I'm having difficulty understanding the latter portion of your response -->

"<text odd_left_stims> containing all items where an odd number is on the left,
<text even_right> all items with an even number on the right, and so forth.

If you wish to administer items and/or trials in a specific sequence, use /select = sequence in the <text> elements and specify the exact order of trials in the <block>'s /trials attribute."

In terms of the items that I have already written syntax for, which the first practice block is comprised of, the items need to be presented in that specific order (i.e., practice1-practice16), however, the correct responses aren't systematic such that it's always left key, right key, up key, down key every four items. Rather, it's left, down, down, down, down, right, down, down, left, right, down, down, down, left, down, down (not asking you to write the whole thing for me, just making it easier for you to see the order I need in terms of the responses to the items).