Hi there,
I have a few blocks that I'm working with, and they are randomly selected in the experiment. Each block has its own page instruction that should appear before the block. How can I make sure that the page that appears before the block is the right one if the blocks are all randomly selected?
One way I tried is multiply the blocks so that each kind of page instruction appears with each block, but I think there is a better way out there.
Thanks!
Assuming that your instruction pages are either <page> or <htmlpage> elements, you'd just enter the correct page in the '/ preinstructions' attribute for the <block> it belongs to.
<block a>/ preinstructions = (blockainstructions)[...]</block><block b>/ preinstructions = (blockbinstructions)[...]</block>
etc.
~Dave
"To understand recursion, you must first understand recursion." - Unknown Zen Master
Ah yes, I totally missed that!
I have another question: If I want to randomize the duration time of the fixation cross, how can I do it? right now it looks something like this:
/ stimulustimes = [1=fixation; 500=forwardmask; 1000=PRIME; 1500=backwardmask; 2000=STIMULI; 2500=blackrectangle]
and I want to randomize the duration of the fixation to between 1000ms to 2000ms.
Gaius:I have another question: If I want to randomize the duration time of the fixation cross, how can I do it?
The only way to do this is to split things up into two <trial> elements, one for the dynamic / random fixation duration and one for the rest of the stimuli:
<expressions>/ fixationduration = round(rand(1000,2000))</expressions><trial fixation>/ stimulustimes = [0=fixation]/ validresponse = (noresponse)/ trialduration = expressions.fixationduration/ branch = [trial.mytrial][...]</trial><trial mytrial>/ stimulustimes = [0=forwardmask; 500=PRIME; 1000=backwardmask; 1500=STIMULI; 2000=blackrectangle][...]</trial>
Hi Dave,
What does / branch = [trial.mytrial] do?
and if I have multiple trials needing fixation cross, does that mean I have to encode all the trials to the branch?
Gaius:What does / branch = [trial.mytrial] do?
It executes <trial mytrial> as soon as <trial fixation> has ended.
Gaius:and if I have multiple trials needing fixation cross, does that mean I have to encode all the trials to the branch?
It's probably easier to give each "actual" trial its own "fixation" trial. E.g. if you have trials a, b and c, each in dire need of a variable fixation period preceeding them, just go for
<trial fixationa>/ stimulustimes = [0=fixation]/ validresponse = (noresponse)/ trialduration = expressions.fixationduration/ branch = [trial.triala][...]</trial>
<trial triala>/ stimulustimes = [0=forwardmask; 500=PRIME; 1000=backwardmask; 1500=STIMULI; 2000=blackrectangle][...]</trial><trial fixationb>/ stimulustimes = [0=fixation]/ validresponse = (noresponse)/ trialduration = expressions.fixationduration/ branch = [trial.trialb][...]</trial><trial trialb>/ stimulustimes = [0=forwardmask; 500=PRIME; 1000=backwardmask; 1500=STIMULI; 2000=blackrectangle][...]</trial><trial fixationc>/ stimulustimes = [0=fixation]/ validresponse = (noresponse)/ trialduration = expressions.fixationduration/ branch = [trial.trialc][...]</trial><trial trialc>/ stimulustimes = [0=forwardmask; 500=PRIME; 1000=backwardmask; 1500=STIMULI; 2000=blackrectangle][...]</trial>