Millisecond Forums

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>