I think I would create a list of 100 rows in which 92 points to a "non-repeat"-procedure, which just displays the number in the number column, and logs the response, and 8 that points to a "repeat"-procedure, that displays the number once and then displays it again, logging the response. Before starting the list you assign numbers at random to the number column in that list. When running the list, just randomly sample rows one-by-one. Hope you understand what I mean.

i can help you 

Hi Thomas,

Thanks for your response. I'm pretty sure I tried this but I need the number to duplicate in a row, so you would have say "100, 405, 304, 213, 567, 898, 898, 981, 235" and so forth at a rate of 100 numbers per minute. Then the participant would be expected to hit the spacebar following the 898 as a "correct response" within the short time-frame that it is shown for. If the participant hits on a single number it would then be recorded as an incorrect response. These will be run multiple times throughout a 90-minute exercise protocol and therefore need to randomise each time in order to negate learning effects. I'm finding it impossible!

Thanks,

Kate

It´s no problem to randomize over and over. Insert the randomization script into a procedure that dominates the list / procedure that shows the sequence of 100 random numbers (the list and the procedures I´m talking about above). In the list of the 100 random numbers, pick eight rows (the first or the last or whichever, it doesn´t matter), that points to the critical test procedure which displays the number at hand twice. Log the response on the first display as INCORRECT and the response at the second as CORRECT. For all other rows in the list point to the "filler" procedure (or whatever you want to call it) which displays the number at hand once. Log this response as INCORRECT. Then sample at random from this list and the position at which the critical numbers being displayed twice will be random across list presentations. I hope this makes sense.

Ok I think I see what you mean! Just one last question though... Other than having another attribute of say "duplicate number" and on the "repeat procedure" having the "number" attribute presented followed by "duplicate" attribute presented, I don't know how else to make a number repeat twice in a row? Is there another method to do this?

As if there is only 8 out of 100 rows with a "repeat" procedure... then surely the same 8 numbers are going to be repeated each time just in a different order? I would need it so that the duplicated numbers are different each time - so that the participant doesn't merely memorize the numbers which are duplicated. Does this make sense?

Regarding the 8 repeats: you can EITHER have two procedures, one repeat-procedure for the critical eight numbers and one non-repeat for all other numbers. OR you can have an additional attribute (i.e., "duplicate number") and use one and the same procedure in which you use an inline script that checks that attribute (e.g., if get.attribute("duplicate number") == TRUE then) and then add a repeat display within that if inline.

Regarding same numbers: no, if you assign new random numbers to your list right before it is displayed, by including it in a dominating procedure that contains the randomization in-line script, you will always have unique values that are shown and repeated. You need to do this by scripting, i.e., include an in-line and program.

Ok thanks very much Thomas! Guess I'll just to learn how to script!

I think this would work:

Dim N As Integer

for i in n=1 to 100

MyList.SetAttrib n, "RndNumber", Random(100,999)

Next N

This will set a random number inbetween 100 to 999 on each row of the attribute "RndNumber" to the list "MyList" of 100 rows that you have defined in your experiment.