[solved] Probabilistic go-nogo task does not run feedback

Hi there!

I am trying to program a probabilistic go-nogo task in Open Sesame. The problem is that it does not run the feedback.

I will first give a short explanation of the probabilistic element. For instance, for a go-stimulus with a 80-20 contingency probability, the feedback will treat 20% of the trials as if it were a nogo-stimulus. In other words, if the participant (correctly) responds to all the presentations of this go-stimulus, he will receive negative feedback in 20% of these trials. However, the participant has to learn that he should always respond to this stimulus, as responding to the stimulus leads to positive feedback in the majority of trials.

There are four different stimuli in the first block; two with 80-20 probability (one go and one nogo) and two with 100/0 probability (also one go and one nogo). Each stimulus is presented ten times (in random order), which makes 40 trials in the first block.

There is a separate cycle for each trial; this seemed the easiest way to deal with the probabilities. I defined a number of variables, including:

correct_response; is set to ‘space’ or ‘timeout’

stimulus_type; is set to ‘go’ or ‘nogo’

probabilistic_contingency; is set to ‘go’ or ‘nogo’

For stimuli with a 100/0 contingency, stimulus_type equals probabilistic_contingency in all trials (either both ‘go’ or both ‘nogo’). For the 80/20 stimuli, they are unequal in 20% of the trials (which is two out of ten, in this block).

My idea was that a participant receives positive feedback in two possible situations:

(1)Participant gave a response (=correct) to a go-stimulus with a corresponding probabilistic contingency ("Run if: [stimulus_type] = [probabilistic_contingency] and [correct_response] = 1")

(2)Participant gave a response (= incorrect) to a nogo-stimulus with a non-corresponding probabilistic contingency ("Run if: [stimulus_type] != [probabilistic_contingency] and [correct_response] = 0").

Negative feedback is provided in the following two situations:

(1)Participant gave a response (=incorrect) to a nogo-stimulus with a corresponding probabilistic contingency ("Run if: [stimulus_type] = [probabilistic_contingency] and [correct_response] = 0")

(2)Participant gave a response (=correct) to a go-stimulus with a non-corresponding probabilistic contingency ("Run if: [stimulus_type] != [probabilistic_contingency] and [correct_response] = 1").

The program runs the experiment, but it just does not run the feedback. When the ‘run if’ of all four feedback items is set to ‘always’, it does show both feedback displays subsequently after each stimulus presentation. Therefore I am sure that I made a mistake in these conditional statements, but I just can’t figure out where or how. I know the responses are registered in some way, because each trial is terminated once the space bar is pressed.

I also tried “Run if [stimulus_type] = ‘go’ and [probabilistic contingency] = ‘go’ and [correct_response] = 1”, but that also did not work out. I have been stuck on this for days now and I hope someone will be able to help me out!

Thanks in advance,
Johanna