When working on a paper that builds off of your earlier work you’ll often need to cite yourself. You will want to point readers to your earlier papers so you don’t have to re-explain all the details. And it shows that you’ve already done (publishable) work on the topic, and that you’re building on previous work, not starting new.
It does seems really weird to cite yourself. And it’s much easier if you’re just talking in general terms:
In our earlier work on x, we showed that … .
But sometimes, you may want to copy a sentence or two, and that’s where self plagiarism comes into play. A lot of people don’t seem to know that you can self-plagiarize. Self-plagiarism is when you copy some of your earlier work without acknowledging where you got it from. Sure, it’s your work, and so it feels like you should be able to give yourself a licence to use it where ever you want. But, when you publish a paper, you give up some of your copyright to that work to the company that publishes the paper. There are ways to include this text without making it sound really awkward, for example:
As we stated in y, “copied text” .
However, when you are submitting a paper, if you include text like the above examples, it is easy for a reviewer to identify the author(s) of a paper, just check the references. So, instead, you need to change this wording so that it sounds like the work you are referencing was done by someone else. You can change it back after your paper gets accepted.
In So and So’s earlier work on x, they showed that … .
orAs So and So stated in y, “copied text” .
If you don’t put the quotes around work that you are copying from an earlier paper, you are setting yourself up to be considered plagiarizing. Especially in the reviewing scenario, where there should be no indications as to who wrote the paper. If a reviewer has read an earlier paper of yours, they may recognize similar text. In this case, they can not be sure if the authors is plagiarizing your work, or if it’s an author re-using his or her own earlier work.
On top of that, papers often have multiple authors. And it’s likely that your earlier paper and current paper will not have the same set of authors. The text in a paper belongs to all the authors, not just the one who actually typed it out. So if you copy it with out acknowledging which paper it’s from, you are not acknowledging all the authors on the earlier paper.
Anyway, the moral is, always cite, even if its yourself that you need to cite. The internet makes it really easy for people to track down earlier papers and check if someone is plagiarizing (whether it’s originally their own work or not).