The habit begins in childhood with what psychologists call private speech: speaking to oneself aloud while playing with a favorite action figure, for example, or making bunny ears out of shoelaces. As we age, most of us converse with ourselves out loud much less often, but at least a couple of studies suggest that most adults and adolescents sometimes speak to themselves audibly. In a 2006 study by psychologist Adam Winsler of George Mason University and his colleagues, 46 of 48 women admitted that they murmured to themselves now and then. And we all talk to ourselves silently throughout life. Psychologists call this type of thought inner speech or self-talk, and it occupies about one quarter of conscious experience. (paywall)
Unless you are an elf, in which case it is elf-talk, of course, but you knew that, didn’t you?
Seriously, see also: On consciousness, Tegmark gets one thing right, says Rob Sheldon, and
But can nature create human consciousness at all?
Also, Great physicists on the immateriality of consciousness