How to present the same randomised stimuli on two computers?

Builder
1

OS Win7
PsychoPy version 1.85.6
Standard Standalone? Yes

What are you trying to achieve?:
I’m building an experiment where two participants will be asked to interchangeably do the task by themselves or observe the other doing it. Participants do the task themselves on ‘their’ computer, so they observe the other doing it on the ‘other’ computer. The two computers have to be in ‘sync’ to show the same stimuli, and follow the same order of loops and trials. After each ‘block’ of trials, both participants will be asked a question about what they have just experienced/observed on their own computers.

What is the problem?
Can’t figure out how to ‘sync’ two computers to show the same stimuli with the same order of blocks and trials, and save the responses data of two participants in separate files.

What did you try to make it work?
I made two separate scripts with adjusted timing, but then randomisation didn’t work. Now I’m making a single script and I can’t work around making two computers to ‘randomise in sync’. I’ve read the thread about interactive studies, but can’t work around how to make two computers to read the same stimuli and follow the same loop randomisation (I use this hack to randomise the loops/‘blocks’.

2

You have identical .psyexp and conditions files on each computer. Then set the random seed in the loop dialog to the same value on each computer to ensure that they randomise in the same way. If you want different randomisation for each subject, just provide new matching seed values on each run.

i.e. computers can’t really produce true random numbers using software alone. The series of numbers appears random but in reality, given the same starting conditions, each subsequent number is perfectly predictable, as the generation process is a deterministic one.

3

This is much easier than I thought. Worked like a charm - thank you!

4

Just another alternate - I’ve had similar issues and a contraption like this is likely to help. This way you need one computer. And an appropriate IO device can be used to capture responses from both