Human Reflexes

Our reflexes are controlled by our Autonomic Nervous System (ANS) – the lizard brain. It controls the involuntary actions of the body. With a reflex, your lizard brain perceives a particular stimulus and it causes an immediate physiological response. The stimulus can be inside of you, such as detecting a high level of carbon dioxide in your blood causing you to breathe, or outside of you, such as a loud sound causing a startle reflex.

Some of your reflexes are things like sweating. Can you choose to sweat on command or not sweat? No. You go out into the bright light, and your pupils constrict. That’s a reflex. All of your food processing is reflex action. Your heart rate is a reflex. The startle reflex is one we are familiar with. That’s a reflex controlled by their lizard brain.

You have many reflexes that you were born with. These are innate or inborn reflexes, but we also develop reflexes throughout our lives. These are acquired reflexes. In fact, we begin to develop these reflexes the day we are born.24 This process is called classical conditioning, or Pavlovian conditioning. As you may know, Ivan Pavlov was doing research on digestion and salivation using dogs in 1901. One experiment was to measure the amount of saliva the dogs produced when eating various amounts of meat. He discovered that dogs were producing saliva before they ever ate the meat. So he designed an experiment to see if he could cause the dogs to produce saliva when he rang a bell.

He gave them the meat, and they would produce saliva. Slightly before he gave them the meat, he rang a bell. Then he repeated the pattern of bell-meat-saliva, bell-meat-saliva. Then, bell-no-meat, and they still produced the saliva. What happened was there was a pairing of the bell and producing saliva because of the meat, so that after repeated pairings, the lizard brain learned that after the bell, its job was to produce saliva – and it did! The stimulus (the bell) and the response (producing saliva) locked together because the lizard brain observed what was happening over and over, so it decided to automatically fire off the reflex because of the stimulus. For years scientists thought it was the association of the bell and the meat that caused the reflex to develop, but recent research has shown that it was the association of the bell and salivation.

Viewing a conditioned reflex as an association between a stimulus and a physical response is particularly significant to misophonia. When I first began studying misophonia and how the misophonic reflex develops, I noticed that there was no unconditioned stimulus (one that would cause the reflex like the meat caused salivation). However, we find a consistent pairing of the trigger stimuli and the initial physical reflex of misophonia, which is generally an unconscious action of the individual.

Developing a reflex is a time sensitive process. To acquire a conditioned reflex response or acquired muscle reflex in humans, the critical timing is about half a second.27 Suppose I had a bell (bing) stimulus and I poked you. Then we repeated bing-poke, where the poke comes half a second after the bell. You will start to flinch after the bing sound, even though I don’t poke you. The timing needs to have the poke occur within two seconds after the bing sound, but half a second is the strongest time delay for acquiring a muscle reflex.

Usually with conditioned reflexes, when you stop forcing the reflex response, the reflex dies out. In the bell-meat-saliva case, if you completely stopped providing meat, the reflex (producing saliva after the bell sound) would die out. But misophonia reflexes don’t die out. I asked myself, “Why not?” The obvious answer is that there is something about experiencing a trigger that is causing the misophonia conditioned reflex to be strengthened. What appears to happen is that you are hearing the trigger (e.g., the crunch sound) and you are having the reflex response. But then you are getting an emotional boost (which tightens the muscle more), so your lizard brain is comparing the crunch sound to a very tight muscle even though the lizard brain only tightened it halfway. So the lizard brain says, “Next time I should tighten the muscle harder.” It seems to be the effect of the emotional response after the trigger that causes the reflex to strengthen, so the misophonia reflex doesn’t die out.