Randomising stimuli

Online experiments
1

Hello everyone! I hope you don’t mind my asking for advice, I’m in desperate need of assistance.

I currently working on a project. Thanks to the joys of Covid, I have to rapidly rework this and must utilise Psychopy for an online experiment. Unfortunately, I have no previous experience with Psychopy or python. So any advice would be welcome :slight_smile:

I have 20 trials. Each trial constitutes the following:

  1. A scenario
  2. An image, with two people presented on screen (Person 1 and Person 2).
  3. An audio for a speech that is associated with person 1 and person 2.

So that the paradigm is: scenario - person 1 on screen = speech 1. Then person 2 = speech 2.

For the purpose of my study I want to randomise the position of the person stimuli I. E., left v. Right. So that the stimuli will be presented as either: person 1 (left) / person 2 (right) OR person 1 (right) / person 2 (left).

The problem I have is the following. The two speeches for each person, are paired with a scenario. So that:
Scenario 1 = speech/person 1/ speech/person 2
Scenario 2 = speech/person 3/ speech/person 4.
An so on, up to 20.

I need to keep the integrity of this while randomising the position (left v right) on screen of the person stim. So scenario 1, must alway be partied with person/speech 1 and 2. But the position of these must be random on screen. The overall order of trials must also be randomised. I. E. Trials 1 - 20.

I am using Psychopy 3.

Any help with this would be greatly appreciated and I hope I’ve been somewhat clear.

Thank you

2

You can achieve this using a loop, check out the documentation on Loops:
https://www.psychopy.org/builder/flow.html#:~:text=Loops,Experiment%20menu%20of%20the%20Builder.

Essentially, you need to have the faces, speeches and scenarios in corresponding rows of an excel table, with this serving as the Conditions file for a Loop set to random. This will make variables with the names you gave to each column (e.g. face, scenario, speech) which can then be set as the value for components in your routines using a $ in the parameter input to show that it should be interpreted as code (e.g. $face, $scenario, $speech)

3

Thank you very much, TParsons. :smiley: