"Lizard brain" describes the part of the human brain that produces behaviour based on instinct (= natural reactions and behaviours that are not under conscious control) or emotion, rather than on reasonable thought or on things one has learned.
It is a colloquial name for the oldest part of the brain, also known as the reptilian complex or limbic system, which controls instinctual behaviors like fear, fight or flight responses, and basic survival needs.
While the idea of a three-part brain (reptilian, limbic, and neocortex) is a simplified theory that has been debunked, the "lizard brain" concept remains popular for describing the primitive, emotional, and instinctual responses that can override logical thinking.
- From online with editing
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Continuing discussion of yesterday's APAD, why do some people "zig when others zag"? Is it possible the auto reaction of ones' "lizard brain"?
Most of us would jump when being hit by an object, and run away from cars running at us. When watching a TV show, I scream loudly every time someone jumps from a building. Guess it's built into my "lizard brain" as I do it automatically and can't help (and hubby sometimes feels like jumping too, not by the scenes, but by my sudden scream 
) .
Think of it, in sports, won't a lot of actions be part of athletes' "lizard brain" reactions? Also the same in wars. Our "lizard brain" reaction speed could be a life or death difference in real life events, sometimes.
And even Maowi the cat depends on his "lizard brain" to survive. 
Good Wednesday and Cheers to all!
