The experts on this forum are affiliated with many organizations across North America. Can you please cite the source of the research to which you are referring?
If you are specifically referring to foods in storage, most any rotting vegetable may encourage rot in nearby vegetables. The decomposers (bacteria, etc.) can spread if they are in close proximity.
In terms of companion planting in the garden, a quick search on the internet did not turn up any references for the potato and onion combination.
I can only suggest you try to contact the author of the blog you refer to.
Okay, if you would be kind enough to point me in that direction because I contacted this author to find out on what basis the information was posted.
Unfortunately, I have no way of identifying who is conducting the research project you mention. Ask an Expert writers are volunteers from across North America and affiliated with many organizations. If you can find the article again, I'd suggest you contact the webmaster for that particular website, providing a url link to the article. They may be able to help you find the author or agency that is involved.