Millisecond Forums

Well, there is a reason for the amount of trials, that being that the task implements a specific (full) design:

Practice: default
- 24 practice trials (6 per target category, e.g. 'green L', order is randomized)
- each possible target is used once per target category - random selection)
- 2 different array sizes per target category (4 stims vs. 16 stims), random selection
- half the trials (12) have the target present (order of 'target present' vs. 'target absent' randomized)
- provides performance feedback


Test: default
2 target colors (green vs. red) x 2 target letters (L vs. T) x 4 array sizes (6, 12, 24, 48) x 2 target condition (present vs. absent)
x 6 reps = 192 trials,
tested in a full, mixed design.

In order to shorten the task, you first ought to decide what about the design you want to change. Fewer repetitions? Fewer array sizes? etc.

Then edit the various <lists> that control the design accordingly (look under TEST starting at approx. line 1175 in the script)

*****************************
Test
*****************************

Note: the following lists control the selection of the target orientation (-> items.stims)
for the selected target category
<list greenL_targetStimItemNumber>
/items = (1, 2, 3, 4, 5, 6)
/ poolsize = 48
/ replace = false
/ resetinterval = 0
</list>

...

and finally adjust the number of trials run by the <block> elements accordingly:

<block practice>
/ preinstructions = (intro1, intro2)
/ ontrialbegin = [
    values.response = "";
]
/ trials = [1 = getReady; 2-25 = noreplace(greenL_practice_start, redL_practice_start, greenT_practice_start, redT_practice_start)]
/ ontrialend = [
    if (block.practice.response == parameters.noKey){
        values.response = "no";
    } else if (block.practice.response == parameters.yesKey){
        values.response = "yes";
    } else if (block.practice.response == 0){
        values.response = "no response";
    };
]
</block>

<block VS>
/ preinstructions = (testintro)
/ ontrialbegin = [
    values.response = "";
]
/ trials = [1 = getReady; 2-193 = noreplace(greenL_start, redL_start, greenT_start, redT_start)]
/ ontrialend = [
    if (block.VS.response == parameters.noKey){
        values.response = "no";
    } else if (block.VS.response == parameters.yesKey){
        values.response = "yes";
    } else if (block.VS.response == 0){
        values.response = "no response";
    };
]
</block>