Who Versus That
There are a few trends I notice both as a reader and editor. One is the misuse of that in place of who in narrative text or formal scripts. Before you argue – note what I actually said: in narrative text or formal scripts. This means areas of your book that is not dialogue (internal – thoughts or narrative by POV – or verbal) and nothing colloquial.
Now, to be fair, who and that are relative pronouns. That means there are things to consider: subject (noun), is it a restrictive or non-restrictive relative clause, or is possessive? Things get more confused when you start to discuss formal versus informal, then whether you plan to publish or not, as the following illustrates:
“One rule that is commonly taught to learners of English is that you can use who to refer to animate nouns (people and pets) and which to refer to inanimate nouns (things). However, that can be used for both animate and inanimate antecedents. Another common rule is that you can use which or who for both defining and non-defining clauses, while that is only used in defining clauses. The most popular grammars for EFL/ESL students and instructors alike present the rules in this way. Moreover, a quick search on any corpus returns hundreds or even thousands of concordance lines that evidence the validity of these rules.
Things begin to get confusing if you ask your students to follow a specific style guide for writing assignments, such as the Publication Manual of the American Psychological Association (APA) or the MLA Handbook (MLA). Both of these guides prescribe the use of that for defining relative clauses and which for non-defining clauses. The APA also prescribes the use of that for non-human nouns (including your pets!) and who for humans. (For APA blog posts about relative pronouns, search https://apastyle.apa.org/). Proponents of these guides argue that using different pronouns for different functions ensures precision and clarity in academic writing. Some proponents might even unbashfully refer to my, now not-so-subtle, ‘puns’ above as ‘errors’.”
https://www.cambridge.org/elt/blog/2021/10/27/which-that-or-who/
THE EASIEST WAY TO REMEMBER
As PUBLISHED writers, if you are NOT writing dialogue or colloquial narrative, you should be FORMAL. Therefore, you want to use this rule:
WHO is used in conjunction with PEOPLE. Ms. Johnson is a teacher who believes in studying.
THAT is used in conjunction with an inanimate object (or things). The pencil that broke during the test was a number two lead.
Even though these pronouns seem interchangeable, they’re not. There are specific times to use each one. Here are some quick ways to remember whether who, that, and which are the right words to use.
That overlaps meaning with who and which. So, why can’t you use that in every situation? It turns out that when you use these pronouns to introduce relative clauses, the sentence’s context determines which pronoun you should use.
https://grammar.yourdictionary.com/vs/who-vs-that-vs-which-fundamental-grammar-rules.html
“Many people use the words who and that interchangeably, but it’s important to know the difference between them. In short, who is used to refer to people, while that is used for inanimate objects, organizations, and types of people.“
https://www.grammarly.com/blog/who-vs-that/