美国博士申请，例如机械工程，计算机，营养学，心理学等专业在博士申请时确实是需要有教授接收，才能录取。但是很多人文社科类专业确实是在申请时不需要确认博士期间的导师，而是到校之后载确认的。
纽约大学的语言学博士项目，针对申请者是否需要提前确认导师的问题专门进行了回答。
I would like to work with Professor X, who teaches in your department. Should I apply by writing to Professor X, or by submitting an application through the regular system?
You should submit your application through the regular system, so we can evaluate your application along with its letters of recommendation and compare it with other applications. Our department does not accept candidates to work with particular faculty members. Applications are approved by the faculty as a whole, across the various fields that our faculty address. No single faculty member is in a position to admit you. The application form asks you to indicate subfield(s) of interest as well as the NYU faculty most directly responsible for your decision to apply. We encourage you to use this to make sure your application is noticed by the most relevant faculty. Your expression of interest is not a commitment on your part. We know you are bound to discover new topics in various fields, and if we admit you we will not hold you to any initial preference you express in your application. Students who have been admitted to the program will not be limited to working with just the faculty they have mentioned in their application.
What if I don’t know yet which faculty member I would like to work with?
This is fine. We do not expect you to know this before you apply. Ph.D. students choose faculty members as program advisers by the end of their first year. These advisers help students progress through the program. In their second and third years, students choose chairs for their qualifying paper committees, and by their fourth year, for their dissertation committees. These roles can be filled by different faculty, though typically there is overlap. Students are not expected to know who they might want to work with in subsequent years, and are free to switch program advisers throughout the Ph.D.
Will I be able to work with Professor X if I am admitted to the program?
This is decided by students and faculty together after students join the program. If for some reason a professor becomes unavailable, we are a large department and most of our subfields are represented by multiple faculty, so you should still be able to find other faculty to work with.
