I read somewhere that a common symptom of Asperger's is lack of empathy.
That has been said about Asperger's traits. I have read this too and the types of questions designed to bring this out in the ASD personality diagnosis tests are intermingled in the test questions.
Here is a link on the biology of the brain in Aspergers and empathy stating some of the things I have listed below.
Neuroscience Sheds Light on Why People with Asperger's Syndrome Lack Empathy | Psych Central
The findings on physical neural network wiring and empathy are what I see as a more scientific way of understanding why some do have empathy and some don't and a spectrum of intensity in between.
I haven't seen any sub-groups listed with these tests except those with sociopathic personality disorder.
1. Pain, emotional or physical, fires off the pain centre of the brain when pain is to self.
2. The same pain centre fires off when seeing someone or an animal hurting, killed or emotionally distressed, other than self. Or hearing of mass painful situations such as war, massacres, or the death of someone. *
This is the neurological test findings for having empathy.
When viewing these *situations happening or hear of it happening to others does not cause the pain centre to fire. Then there is no empathy. No compassion is felt. No bodily reactions or emotional distress.
The only sub- group listed in the neurological tests were the sociopathics.
When veiwing these situations, the pain centres do not fire either, but can go a step beyond to firing the pleasure centre of the brain causing anything from a calming effect to excitation or arousal.
This type of testing was using groups of people with no known mental illness. Here the empathatic pain arousal centre fired vs mild to severe sociopaths where the pain centre did not fire and on some the pleasure centre did instead.
One could try a simple test on self:
Watch a very graphic horror movie, an episode of psychopathic analysis such as Criminal Minds, or
even the news with some real life graphic content.
Now pay notice to how you feel physically and emotionally.
Do the scenes cause feelings of compassion, shock, mental or physical upset?
Or a neutral don't care?
Or instead of jumping at a scary scene or feeling ill from a bloody body scene, there is a calmness?
Professor Psychopath...
(Instinct) series quote.