The stimulus presented is rough around the edges

Hello, everyone. In an experimental program I wrote by myself, round stimulus needs to be presented. When it is presented on my computer screen, it is a smooth circle, but when it is presented on the computer screen of our school laboratory, it is a circle with very rough edges and intermittent pixels can be seen. I would be very grateful if anyone can tell me why and how to solve the problem.

Both screens have similar resolution and refresh rate, the laptop 2560x1600,120Hz, 35cm wide, and the lab computer 2560x1440,120Hz, 60cm wide.

Hi @Jonathan_Fu,

Could you share more details on how you’re creating the circle? Which units you’re using etc?



Thank you for your reply. I created a circular stimulus in builder interface with Polygon, with a radius of 1° in units of ‘deg’.

Thanks so much!

In that case, do you have your monitor configured correctly in the PsychoPy that’s installed in the school laboratory machine?



There are two different versions of psychopy installed on the computer in our lab. I ran my experiment program on the relatively new version of 2022.2.5, and my experiment program was also written on this version of psychopy, but later I updated the version of psychopy on my laptop to 2023.1.1. The program runs without problem.

When running the program on the laboratory computer, I set the screen configuration according to its screen parameters. The resolution is set to 2560*1440, the screen width is 60cm, and the viewing distance is 57cm. The stimulation size calculated accordingly should be consistent with that on the laptop screen, but because the laptop screen is 16:10, while the laboratory screen is 16: 9. So the stimuli in the sensory lab occupy a smaller area on the screen. Do these factors lead to abnormal stimulation?

Thanks a lot.

Hmm that all sounds like it’s set up correctly @Jonathan_Fu.

Does the issue persist if the stimulus is made slightly larger on that screen, say 2 or 3°? I know that’s not a solution but it could help to figure out what could be causing it.



Thank you very much for your reply, I will have a try next time and tell you the consequence.

Hello, today I adjusted the size of the stimulus and ran it on the computer in the lab. The pixels around the stimulus were still visible. Then I tried to turn on the anti-aliasing FXAA function of psychoy in the graphics card setting, and the serrations around the stimulation were relatively reduced. I can’t understand why the same program would look so different on a 16-inch laptop screen and a 27-inch monitor. I would like to know if psychopy has any code or algorithm optimized for stimulus edge anti-aliasing, similar to some of the features in psychtoolbox?