We are the sum total of our life experience, which includes incidents we've personally experienced and those we've read or heard about, all of which become memory. Some incidents, either directly experienced or learned indirectly will resonate for us when we encounter analogous circumstances while others will not. I vividly recall a remark from Uta Hagen when she told my class that there are many characters each of us can play. She reached her arm behind her and dangled her hand up and down from her wrist, and I could see the lineup she was indicating of all those characters behind her. Then she said that as well, there were characters we couldn't perform either yet or ever, depending on our life experience.
I think that if the actor plunges directly into the actions of the character, that actor will very soon discover the extent to which the character's needs resonate. It will either be conscious or subconscious, but the analogy will be there. Remember Robert Lewis's observation that it isn't necessary to consciously know what specific incident from one's own experience resonates. I've personally experienced that he was correct, and have worked with many actors who, in the beginning of rehearsal are clueless why they understand the need of the character, and then, as we work, they remember incidents sometimes uncannily similar or strongly analogous to what they already know about their character's needs.
We don't know what we don't know, and we can't imagine what we don't know, but we do know what we know! Our imagination is derived from our life experience. You don't ever forget anything that has happened to you, Stella Adler said -- I just can't remember if I read it, or heard her say it in one of her lectures on YouTube.