Realised afterwards that I committed mild plagiarism in a paper I wrote as an undergraduate, what should I do? A few years back, while still an undergraduate student, I wrote and submitted a paper to a (low-tier) journal. It was accepted and published. None of the professors in my college were familiar with the subfield in question, so I did it all on my own, without their supervision or assistance.

It was only later on that I realised that I was guilty of plagiarism. I did write the paper all on my own, and always provide appropriate citations, but sometimes I would quote single sentences or parts of them directly from my sources without indicating that they were direct quotes (even if these unmarked quotes were always followed by a citation to the original source).

It has now been several years but I keep feeling guilty about it, and worry that one day someone will notice it and call me out on it. Or at least notice it while reading the paper and think worse of me. But since it has been several years since the paper was published, I also don’t know what I could do about it. I have thought of putting something like a public admission and apology on my website (from which the paper can also be downloaded), but maybe I’m overthinking it and nobody would actually care. In that case it would feel like a bad idea to needlessly draw attention to something that nobody would have noticed otherwise. But the paper has been cited some times, and I have reason to expect that there will be people reading it in the future.

Should I do something about it or just let it be?
but sometimes I would quote single sentences or parts of them directly from my sources without indicating that they were direct quotes (even if these unmarked quotes were always followed by a citation to the original source).


"You didn't use quotation marks where you should have in a paper you wrote as an undergrad? My god, you are despicable human being."

Nobody reading your question here will think this. 

Rather they will think something like:

"Wow, you wrote a journal paper on your own as an undergrad and it's still being cited?"

I would imagine that the vast majority of readers of your paper, even if they notice, would think likewise.



Though it's technically plagarism, I think it would be quite obvious to a reasonable reader that if your intent was to plagarise, you would not immediately cite the plagarised document you stole the quote from. Omitting quotation marks sounds like a minor transgression to me, particularly if your area is STEM where the (natural) language of the text is a means not an end. (If you did not have the citation(s) at all, I think it would be a different matter.)

Mistakes happen and this was clearly just a mistake.

(I would also add that I think it's pretty common for researchers to be somewhat embarrassed by earlier papers that they wrote when they were more junior. At least I am. But that's just a sign of improving.)


  I also don’t know what I could do about it. I have thought of putting something like a public admission and apology on my website (from which the paper can also be downloaded)


I would suggest two things:


Update the preprint on your homepage.
Keep a list of errata on your homepage.


In my area (CS) people mostly read the preprints (found through Google or Google Scholar). 


  public admission and apology


I don't think there's a need to apologise. I think you just need to admit your mistake and move on. Again, mistakes happen!