By wessa - 11/12/2015
Hi,
in a learned helplessness task I would like to insert a probabilistic feedback after a response is given by the subject, i.e. a feedback that is not contingent to the accuracy of the response. More precisely, the subject should receive a "punishment" feedback (in our case waiting for 12 sec until the next trial starts) in 75% of the trials and a "reward" feedback (waiting for only 2 sec until the next trial starts) on 25% on the trials but always irrespective of the correct or incorrect answer the subject has given.
Any idea on how I could implement that in the script? Is there any option by using the select attribute? Or by using a counter? If yes, how would I concretely write it in the script?
Thanks a lot for your help and looking forward to hopefully quick answers,
Michèle
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By Dave - 11/12/2015
You can, for example, enter your "punish" and "reward" trials into a <list> in the desired proportions and then /branch from your "main" trial(s):
<block myblock>
/ trials = [1-100=mytrial]
</block>
<trial mytrial>
/ stimulusframes = [1=mytext]
/ validresponse = ("d", "k")
/ correctresponse = ("k")
/ branch = [list.feedbacklist.nextvalue]
</trial>
<trial punishment>
/ stimulusframes = [1=punishtext]
/ validresponse = (0)
/ trialduration = 12000
</trial>
<trial reward>
/ stimulusframes = [1=rewardtext]
/ validresponse = (0)
/ trialduration = 2000
</trial>
<list feedbacklist>
/ items = (trial.punishment, trial.reward)
/ poolsize = 100
/ itemprobabilities = (.75, .25)
</list>
<text mytext>
/ items = ("Press D or K")
</text>
<text punishtext>
/ items = (":( Wait for 12 seconds.")
</text>
<text rewardtext>
/ items = (":) Wait for 2 seconds.")
</text>
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By wessa - 11/12/2015
Thanks a lot Dave, that helped a lot.
Best,
Michèle
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