Anyone who has unconsciously driven past their intended exit off a highway, has likely experienced what we call highway hypnosis. This is another example of an accommodation our brains makes to having to run on only 20 watts of power. Population biologist, David Krakauer, marvels at the multiple awareness a life form has that allow it to gather and aggregate data from diverse sources, match it to remembered data algorithms, and make decisions in a thousands of a second. It's an example of intelligence that doesn't require consciousness, much less meta-consciousness, a conscious monitoring of our consciousness-driven behavior.
Hypnosis
My attention has drifted away from the highway. In this case, I was paying attention to an archetypal highway, the experience of driving, and the experience of losing conscious awareness while nonetheless, keeping a rapidly moving automobile between the lane lines and safely behind the vehicle in front. I'm imagining a real highway again.
A familiar road on the way to a familiar destination can put our brains on autopilot. It has reduced awareness to either opportunity or threat. It's going through the motions. It's not tracking time or distance, and in the absence of a particular opportunity or threat on the asphalt in front of us the familiar surroundings don't trigger awareness.
Wait. Where am I?
Habit
Getting us to repeat the same thing in the same circumstances over and over again is another way our brains save energy. It may be a good and useful thing like brushing our teeth or regularly eating ice cream before bed and after brushing. Most of us have contradictions like that. The lobby of my pool offers delicious-looking pastries for sale and do a brisk business from people leaving their workouts.
Bias
On my wall is a small three-dimensional representation of the U.S. flag created by the artist, Dave Cole. From a distance, the stars and stripes appear crudely drawn over a rough surface. In a closer look, the rough surface is from plastic toy figures representing humans. There are two types. They're from a set made for children's play in the middle of the last century. They are crude representations of what would have been identified as Cowboys and Indians. They are in hand-to-hand combat positions crammed as if in mortal combat on a small board. There are no personal identifying features, just crude images in stereotypical costumes.
Our brain has shortcuts: biases, stereotypes, that allow us to sort us from them. Our brain doesn't have to reason why. A seven-year-old in 1962 could gleefully engage in the imaginative play of slaughtering others who dressed differently. One needs to exert considerable mental effort -- not intelligence -- effort to bring others into our circle of belonging.
Agency reversal
All of this is our brain conserving energy. The work to consider, evaluate, discern, decide, require significant mental energy. Our brains want to be simple minded. Our brains want to turn over the work of consideration, evaluation, discernment, and decisions over to outside forces. The desire of our brain to conserve energy allows us to see other humans as simple representations of friend or foe, so they can be accepted, dismissed, even destroyed when we feel threatened.