The answer to this question is Amygdala
Amygdala has proven to be the main center of emotional response that exists in almost all mammals.
One study showed that after stimulating this part of the brain on rats, the rats will show sudden aggressive behaviors towards the researchers
"Clinical observations and testing" have contributed most of what we know about personality today...
Clinical observations are the examination of conduct from
the patients that are utilized to decide an analysis and treatment design.
Commonly notes are taken amid the collaboration with the patient or at times after.
Clinical observations are the premise of treatment and are the methods at which
an expert can find out about their patient.