preconceived
adjective uk/ˌpriː.kənˈsiːvd/ us/ˌpriː.kənˈsiːvd/
（想法或观点）事先认为的，预想的；（尤指）未充分考虑的
(of an idea or an opinion) formed too early, especially without enough thought or knowledge
You must judge each film on its own merits, without any preconceived notions about what it's like. 你必须根据每部电影各自的优劣来作出判断，不应该先入为主，存有成见。