It would be interesting to be able to capture this very personal mental narrative and compare notes between people, cross-referenced with other factors, like accomplishments, feeling of success as well as general health and mental wellbeing. While I have no reliable visibility on this, my intuition tells me there is quite a difference between people in how our internal voices speak to us.
I would be so very interested in the results of such a study if it were possible.
As I look back on my life and various experiences, I can distinctly hear both voices at different times in my life. What is strange to me is how they are equally powerful as far as the results of my actions based upon those inner thoughts. It would so beneficial if one could learn to harness the positive and suppress the negative.
Thinking back on these personal eras, the positive voice allowed me to attain achievements I once thought were impossible and the negative voice has taken me to the very edge of personal destruction. It is fascinating just how powerful our mind is.