Disclaimer: This is just my theory and is not based on facts.
I imagine a normal person should have only one focus. But somehow, the person with Schizophrenia has one focus outside and another focus inside. The focus inside makes him/her aware of hallucinations and delusions. Meanwhile the focus outside is less powerful now (e.g. lack of motivation) because it is divided into two polarities.
Split of focus:
Focus inside the Schizophrenic: Positive symptoms of Schizophrenia
Focus outside the Schizophrenic: Negative symptoms of Schizophrenia
Normal focus, either inside or outside: No symptoms of Schizophrenia
I think that one of my psychology teachers espoused a similar theory.He was into the dopamine hypothesis, and argued that excess dopamine causes non-focused attention.There are a lot of related Google scholar papers on a similar theme. https://scholar.google.co.jp/scholar?q="attention+focus"+schizophrenia
im sorry @eeee that was just ranting… that’s what they tell us… I have a problem with this way of thinking not with you I will make a diff topic for it…