Millisecond Forums

Hi Dave,

Sorry to bring up an old topic, but I'm still failing to acquire a proper randomisation of the lists in terms of by time, and then by condition, so that the participant receives both blocks of stimuli presentation times of 500, and then 900 (also randomly presented) before continuing onto the next condition. Currently, they are experiencing a completely randomised presentation, i.e., the stimulus times aren't being presented one after the other before moving onto the next condition.

*********
Block list
*********

<list masterblocklist>
/items = (list.baseline.nextvalue; list.self.nextvalue; list.countdown.nextvalue)
/poolsize = 6
/selectionmode = noreplacenorepeat(1,1,2,2,3,3)
</list>

Conditions:

<list baseline>
/items = (block.baseline500, block.baseline900)
</list>

<list self>
/items = (block.self500, block.self900)
</list>

<list countdown>
/items = (block.countdown500, block.countdown900)
</list>

*********
Blocks
*********

<block baseline500>
/preinstructions = (Baseline)
/trials = [1-10 = noreplace(baselineclickprac500); 11-20 = noreplace(baselineclick500)]
</block>

<block baseline900>
/preinstructions = (Baseline)
/trials = [1-10 = noreplace(baselineclickprac900); 11-20 = noreplace(baselineclick900)]
</block>

<block self500>
/preinstructions = (Self)
/trials = [1-10 = noreplace(selfclickprac500); 11-20 = noreplace(selfclick500)]
</block>

<block self900>
/preinstructions = (Self)
/trials = [1-10 = noreplace(selfclickprac900); 11-20 = noreplace(selfclick900)]
</block>

<block countdown500>
/preinstructions = (Countdown)
/trials = [1-10 = noreplace(countdownbeginprac500); 11-20 = noreplace(countdownbegin500)]
</block>

<block countdown900>
/preinstructions = (Countdown)
/trials = [1-10 = noreplace(countdownbeginprac900); 11-20 = noreplace(countdownbegin900)]
</block>

Pardon if I did not explain myself properly before, or I implemented your advice incorrectly.

Many thanks,
Josh

I suppose I don't understand what this means then:

"a proper randomisation of the lists in terms of by time, and then by condition, so that the participant receives both blocks of stimuli presentation times of 500, and then 900 (also randomly presented) before continuing onto the next condition."

Could you give a concrete example, please?

And what does

"Currently, they are experiencing a completely randomised presentation, i.e., the stimulus times aren't being presented one after the other before moving onto the next condition."

mean, particularly " the stimulus times aren't being presented one after the other"? Here, too, please give concrete examples. Thanks.

Hi Dave, 

Sorry for not explaining it clearly. What I meant to say is the participant should see both time intervals of the condition, before advancing to the next condition, i.e.  one participant might see: Baseline 500, Baseline 900, Countdown 900, Countdown 500, Self 900, Self 500, whilst the next participant might see Countdown 500, Countdown 900, Self 500, Self 900, Baseline 900, Baseline 500. What I meant by a 'completely randomised presentation' is that the participant currently experiences the 6 (in total) time by conditions randomly without the pairing of the time intervals, e.g., Baseline 500, Self 900, Countdown 900, Self 500, Baseline 900, Countdown 500.

Many thanks,
Josh