This gesture suggests insecurity, protectiveness, concern, worry, nervousness, defensiveness, threat, discomfort, anxiety, or fearfulness.
Evolved from the instinct to protect the main artery in the neck area. It’s an automatic, unconscious defensive signal in response to threat or stress.
This gesture is exhibited also by touching or pulling shirt’s collar. In females this gesture is also exhibited by touching or playing with a necklace or imaginary necklace.