My understanding of the relevant research* is that it's a fairly consistent finding that masculine generics (a) do cause people to imagine men rather than women, and (b) that this can have negative effects ranging from impaired recall, comprehension, and self-esteem in women, to reducing female job applications. (Some of these negative effects have also been established for men from feminine generics as well, which favours using they/them/their rather than she/her as replacements.)

* There's an overview of some of this here (from p.26).