Hi! Participants are presented with pictures and then fixation cross. I need to set duration for the fixation cross from 3 to 3.5 seconds. It should be random each time. I am a complete newby in Python and already tried several codes proposed on the forum. Unfortunatelly, they do not work for me. C…

Hello, does this RandFix.psyexp (13.5 KB) run? Best wishes Jens

It is only in the text component settings. I also tried ‘duration (frames)’, ‘frame N’ and ‘condition’. [PrtScr capture_418]

Hello, there is no need to use “set every repeat” if you don’t change the stimulus. It can be constant. Which psychopy-version are you using? I’m using 2020.2.10 Best wishes Jens

No, a more recent one: PsychoPy 2021.1.2

Hello, what happens when you set your PsychoPy to use an older version (edit experiment settings → use PsychoPy version)? Best wishes Jens

Error: if bool(asarray($fixDur)): ^ (arrow on dollar sign) SyntaxError: invalid syntax Experiment ended.

Yes, it looks like this: [PsychoPy_2] And gradually counts down/

Hello, looks good. It is not a count-down. :wink: The number in middle stays on screen for a period lasting between 3 - 3.5 sec. How “large” is your experiment? If it is not too large, you could use this example to build your experiment. Best wishes Jens

it’s from 250 to 500 stimuli. is it too big to use what you’ve sent me?

@JensBoelte means in terms of numbers of routines. 500 stimuli could still just be one routine with a couple of components in one loop.

Thank you. When I copy-paste your code in my experiment, weirdly it refuses to work. Again because of $ dollar sign in the duration line. I guess the only chance is to rebuild my experiment in your file. Sounds like nonsense, but we have what we have :frowning:

Randomize duration of a Routine in Builder

Builder

wakecarter March 21, 2021, 10:23am 16

Have you tried without the dollar sign?

Builder inserts useless asarray calls in py code

Topic		Replies	Views
How to code to get a random time for the fixation cross? Builder	24	2730	February 17, 2023
Time randomization for a stimulus in a routine Builder	17	8733	September 6, 2022
Ramdon fixation during biased toward the lower end Builder timing , randomization	1	398	January 7, 2021
Fixed stimulus duration chosen randomly Builder	12	3481	March 30, 2021
Fixation routine with random duration before a movie routine behaves with wrong duration Builder timing , movies	7	97	April 10, 2026

Randomize duration of a Routine in Builder

Related topics