CODEWITHSUNDEEP
psychopy
Cashel Godfrey
Cashel Godfrey

Reputation: 53

Understanding PsychoPy codes for trialHandler and responses

I am new to coding, and would like help in understanding the script used by the PsychoPy program.

To be more specific, I would like to understand the codes that are in line 6 to 15. I am aware that this is used to manage the multiple trials, but I am hoping someone can help me clarify those bits? I also noted that removing the codes from line 6-8 doesn't change the experiment, but removing the codes from line 10-15 essentially stop the experiment from running. 

trialsAll = data.TrialHandler(trialList=data.importConditions('trialType.xlsx'), nReps=10, method='random', name='trialsAll', dataTypes='corr')
thisExp = data.ExperimentHandler(name='Ours')
thisExp.addLoop(trialsAll)  #adds a loop to the experiment
thisTrial = trialsAll.trialList[0]

if thisTrial != None:
    for paramName in thisTrial.keys():
        exec(paramName + '= thisTrial.' + paramName)

# Loop through trials
 for thisTrial in trialsAll:
     currentLoop=trialsAll
     if thisTrial != None:
        for paramName in thisTrial.keys():
            exec(paramName + '=thisTrial.' + paramName)

My second question would be about getting responses. Is there a reason that thisResp is equalled to None? 

#get response
thisResp=None
while thisResp==None:
    allKeys=event.waitKeys()

Thanks a lot for any help. I appreciate it.

Regards, Cash

Upvotes: 2

Views: 826

Answers (1)

Cashel Godfrey
Cashel Godfrey

Reputation: 53

if thisTrial != None:
    for paramName in thisTrial.keys():
        exec(paramName + '= thisTrial.' + paramName)

This code allows the use of abbreviations. For example, say your conditions file has a field called 'angle', you can refer to this directly rather than via the keys of that trial's dictionary (e.g. thisTrial['angle'] ) or using dot notation ( thisTrial.angle ). i.e., in this example:

angle = thisTrial.angle

for thisTrial in trialsAll:

is fundamental to running a psychoPy trial loop. It will cycle though each trial that is contained in the TrialHandler object that is created to manage trials, connected to a given conditions file. 

#get response
thisResp=None
while thisResp==None:
    allKeys=event.waitKeys()

The line 'while thisResp==None:' requires that the variable 'thisResp' actually exists if we are going to be able to check its value. So in the immediately preceding line, it is created and given an initial null value so that the next line will run OK. Note that at this stage, it is just an arbitrary variable, which doesn't have any actual connection to the subject's response. That will presumably occur later in the code, when it gets assigned a value other than None.

Upvotes: 2

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