I am currently reading an old but still relevant book on abuse by John Gottman and Neil Jacobson called "When Men Batter Women." One distinction that Gottman and Jacobson (hereinafter referred to as G/J) make is between "Pit Bulls" and "Cobras." Typically, when people start to argue, their heart rate goes up, they begin to sweat and feel overwhelmed, and they begin to show signs of a possible verbal attack. Pit Bulls are described as men who are highly insecure and fear that their wives will abandon them. Pit Bulls are often passive-aggressive and will exhibit anger in increments until they "explode" at their spouse through acts of violence, such as hitting, throwing things, and attacking their partner. Women in these relationships are often not as intimidated by Pit Bulls and will argue as vociferously as their husbands.
Cobras, on the other hand, are quite different. These men are not afraid of abandonment but want to be "left alone" when their wives are "bothering them." In contrast to Pit Bulls and non-violent men, Cobras will actually have a LOWER heart rate when they attack their partners. In 20% of the batterers that G/J studied, there was a decrease in heart rate as they became more verbally aggressive. In a sense, they derive some pleasure from hurting their partner. These men may appear and sound aggressive (yelling and screaming), but if you were to measure their heart rate, it would seem as if they were in a calm and collected mental state. Just like a cobra that becomes quite still and focused before attacking its victims, Cobras are more likely to use severe violence to "shut their partner up" when provoked.
Cobras exhibit severe evidence of antisocial, criminal-like traits and are sadistic in their abuse. They are not emotionally dependent on their partners but are much more dangerous. The unfortunate news here is that Cobras do not change. The only remedy that G/J offer is prison time, and they provide a much-needed correction to our hyper-therapeutic age, suggesting that Cobras will not change through psychotherapy. They don't. If anything, they are often skilled at manipulating therapists into believing that they are cured.
If you are in a relationship with a Cobra, leave. I understand that it's difficult. You may be financially dependent on them, and you may have children with them. However, all the evidence indicates that these men do not change, and the abuse will only worsen over time. Unfortunately, too many churches, organizations, and outpatient programs attempt to offer "mediation" for these couples. The sad reality here is that mediation cannot be offered. Only safety can.
If you're unsure whether you're with a Cobra, ask yourself, "Does his heart rate LOWER when he's screaming at me?" If the answer is yes, seek immediate safety.