In psychiatry, the term neologism is used to describe the use of words that have meaning only to the person who uses them, independent of their common meaning. This tendency is considered normal in children, but in adults can be a symptom of psychopathy or a thought disorder (indicative of a psychotic mental illness, such as schizophrenia). People with autism also may create neologisms. Additionally, use of neologisms may be related to aphasia acquired after brain damage resulting from a stroke or head injury
Why have I perceived I only have one tongue my whole life? I think it is because that I use it as one tongue instead of two tongues co joined. The dominant right side became the proxy for the movement with the left adopting a subordinate passive role. If I think of my tongue as two hands clasped (as it must be as it is innervated that way) I can begin to ask the question, "am I moving the left tongue independent of the right?" My habitual is that I do not.
The bit between our teeth
Why would I develop the right side as the dominant tongue? Is it because I have to use the musculature of the right tongue in the dynamic patterns of speech? I can write with my left hand badly. I never attempt it because there is no need too. I write better with my right. It's a pain in the ass to write with the left hand. Can I speak with my left tongue badly? Before I can speak with it I have to differentiate it as my left tongue. Then I have to learn use my left tongue in a new way.
Is it a matter of consequence? Perhaps only to the twisted.