into one's head

It would have to be structured, with specific things to respond to, like the prompts in a word-association test; unstructured, like the task of saying whatever comes into one’s head; and, like hypnosis, able to get around our conscious defences to reveal what we don’t know we know, or don’t want to know.

Here, at last, I am resting from hard times at Marienbad, where the waters get into one's head, as my letter will probably show.

Michael Frayn: Ideas for things come into one's head, or bits of ideas; you feel there's something – there's some meat on the bone, there's something there that lures you on.

Criticism consists in saying whatever comes into one's head.

Sometimes ideas come into one's head that upset principles and everything.