[milkshakes]

reminds me of this: https://www.reddit.com/r/LifeProTips/comments/5jdzsx/lpt_use...

[JadeNB]

This was used in some early-20th-century astronomical setting, I think to detect supernovae. I can't find any documentation now, but my memory is that it was called "blink testing" or something similar, where one switched rapidly between two images of a star field so that changes due to a supernova would stand out.

[rogerrogerr]

https://en.m.wikipedia.org/wiki/Blink_comparator

[CGMthrowaway]

I went cross-eyed on my screenshot, and I couldnt read the word, but I did notice some artifacts