Posner task in Psychopy

Hello to everyone,

I want to prepare a posner task. One of these directional signs “<” or “>” will appear after two photos, one neutral and one threatening, appear on the screen. These direction signs will come after the 80% neutral photo. I can’t make this part and these marks ("<",">") come up randomly.

I would be glad if you help

Hi, can I confirm if you are referring to having 80% of neutral images and 20% of threatening images here? Or are you referring to the </> appearing at 80% of your neutral trials and never your threatening images?

Yes, I am refering to the </> appering at 80% of my neutral trials.

neutral_flanker.zip (17.4 KB)
Based off my understanding, I’ve made a minimal demo. Hopefully this helps

Thank you so much for taking the time and sharing your demo with me. I realize that I have described the experiment in a wrong way. My English is not very good, sorry for that. I’m sending you the experiment I want to do. I set the arrows to come after the 80% neutral photos through the excel file. However, I can’t set it to come randomly.
Thank you again
posner.psyexp (25.2 KB)
condition.xlsx (9.8 KB)


Hi Katty, I’m afraid I’m still unclear on what you mean by this. Based on your psyexp file, you would first like to briefly show 2 images (one on the left and the other on the right). A fixation cross will appear in the middle of the screen throughout.

After that, you have your target stimuli appearing on both sides of your screen and then the participants respond by pressing the space bar.

In your conditions file, the showTargetLeft and showTargetRight columns are currently empty. You also have three types of trials (i.e. neutral/threatening, threatening/neutral, neutral/neutral). On which of these trials would you like your target to appear?