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Jittered fixation cross from the builder view


#1

Hi,

OS (e.g. Win10): HighSierra 10.13.4
PsychoPy version (e.g. 1.84.x): 1.85.4

In the experiment attached, how could my fixation cross appear for a random duration between 1500ms to 3500ms?

Many thanks for your help,
Genevieve run1.psyexp (14.6 KB)


#2

Hi @Genevieve_Allaire-Du. You can add a code component before your fixation point. Add the following to the “Begin Experiment” and “Begin Routine”:

jitter = np.arange(1.5, 3.75, .25)
shuffle(jitter)

Add $jitter[0] to Start or Stop in your text stim, and this will feed a random jitter time to each trial.


#3

Hi David,

Thank you!

If I understand correctly with this command line, the duration will vary randomly between 1.5 and 3.5 sec. with a .25 sec distance between the possible values?

Genevieve


#4

No problem. Yes that is what will happen, but you can check by printing the jitter list in the code component. This will show you all available values that can be used for jitter