Most people talk to themselves as an extension of their inner thought processes. Research has shown that talking to oneself is generally psychologically healthy and even beneficial. However, excessive use of the practice could be a sign of mental problems.
The human mind is often chatting to itself, and people reason through problems and think about ideas through this phenomenon. While these thoughts are generally not verbalized, some people say them aloud on occasion. Many find it helps them to keep their thoughts on target, and it can help people stay focused. However, it can be a nuisance to others who are nearby, so most people only do it when they are alone.
Talking to oneself can also unveil a variety of thought patterns. People do not generally devote their full attention to the thoughts in their minds, and they may not be aware of negative thought patterns that can arise. Verbalizing thoughts can give people a helpful tool for reflection.
However, some psychological problems can cause people to talk to themselves. Those suffering from schizophrenia, for example, often present with this symptom. In some cases, they may be talking to others who are not around but who they think exist. Those who suffer from schizophrenia, however, often present other clear symptoms in addition to speaking to themselves.