Discarding some trials from feedback

[Shivani R]

Hi,

I am designing an experiment using E Prime in which the subject is
presented with a stimulus, he/she hears a tone and then has to make a
decision after hearing the tone. The feedback is getting displayed
after every 25 trials and there are total 1400 trials. Any decision
(whether correct or incorrect) made before hearing the tone should be
discarded (not taken into account for getting feedback). I am quite
new to E Prime and facing a lot of problem in putting this logic in my
script.

The script that I have now is as follows:

'Stimulus comes up on the screen followed by a tone and next there is
Wait1 object to collect the response. Any response to Stimulus object
(which is a response before the tone) should be discarded. Any
response to Wait1 object (which is after hearing the tone) should be
taken in the feedback.

Dim TrialAcc As String

'If subject responded to Stimulus, this is before the tone and the
trial is logged as incorrect
If Stimulus.RESP <> "" Then
TrialACC = "0"

'No response to Stimulus, but correct response to Wait1 is a correct
trial
If Stimulus.RESP = "" And Wait1.ACC = 1  Then
TrialACC = "1"


'No response to Stimulus, but incorrect response to Wait1 is a
incorrect trial
If Stimulus.RESP = "" And Wait1.ACC = 0  Then
TrialACC = "0"

End If

'The AddObservation command adds the ACC value to the Summation
object, Acc.
Acc.AddObservation Trial.ACC

Debug.Print "TrialAcc = " & Trial.ACC


'The Debug.Print command prints the mean value of the Summation
'object, Acc, in the Output window.
Debug.Print Acc.Mean

c.SetAttrib "OverallAcc", Format(Acc.Mean*100, "00.0")


So actually, right now if the subject makes a response before hearing
the tone, irrespective of whether it was correct or incorrect, it is
taken as incorrect. But I don't want to include this trial info at all
in my feedback. I want to discard this. For eg. if out of 2 trials
subject responds to first trial before hearing the tone and then for
the next trial he responds after hearing the tone and that too
correctly, then he should get overall accuracy as 100 and not 50. The
first trial where he responded before the tone should not be taken
into consideration in his feedback for overall accuracy. I tried a lot
but unable to put this logic in my experiment. Any help is really
appreciated.


Thanks
Shivani

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