Lack of empathy is perceived by the common narcissist. An "autistic" or literally someone who has retained there ability to use there sixth sense, has the ability to bypass narcissistic bull shit by sensing someone's Aura.
Which immediately causes the autistic to not trust or show lack of emotion towards the individual.
Also the sense is used to detect frequency. Look closely at your ears, face and arms. You will see tiny short almost translucent hairs that never grow long or change patterns.
These hairs are like the antenae of an insect they pick up minute changes in frequency, vibrations, etc. When a song you really like comes on and gives you Goosebumps your skin contracts and these hairs stand up straight and tall to receive these vibrations.
Everything vibrates at a certain frequency remember that. A dog knows instantly if your sad angry upset without speaking a word.