For a long time I have read stuff about different types of personalities and ways to categorize them. The most famous is Myers Briggs personality test, which divides people based on whether they are feelers or thinkers, whether they are introvert or extrovert, etc. But often times I think the parameters as described in Myers Briggs might not be mutually independent of each other. For example, someone who is introvert is far more likely to be a thinker. And another problem is this categorization is often highly subjective, dependent of how the person sees himself or herself. There is no way to objectively measure these parameters.
I have known myself to be a sensitive type of person and recently on reading some literature on neuroscience, I think I can relate it to a certain mechanism in my brain, an active and vibrant sympathetic nervous system. When you have highly active sympathetic nervous system, you feel even imaginary pain or perceived pain strongly. That is if you see someone in pain, you almost feel their pain. This makes you somewhat high conscience person.
So the degree of activity in your sympathetic nervous system will be a parameter. Two more parameters would be Drive, and Ability of abstract thinking. The most likely neurological explanation of drive, a strong desire to do something and succeed, is the degree of response to stimulus in your brain. To a large extent this will be governed by environment. If you have seen people dying you have a strong drive to survive. If you have seen people prospering, you have a strong drive to succeed.
The third is ability to do abstract thinking. This perhaps has to do with the intercommunication within your brain regions.
So any person’s personality should be explained by the three parameters, ability to connect to others, motivation to bring in change and ability of reasoning and pattern matching. And we should be able to measure each of these using scientific methods like EEG and MRI scan. A pure objective measure should be possible for each three dimensions.