The “human Thinking Stack” is not a scientific fact but simply my model of how human thinking is organized. It is based on the ISO OSI model of computer networking. In that model’s terminology, interaction between computers is controlled by a communications stack—thought of as layers of networking protocols, which are the procedures that programs use to talk to each other, each communicating with the protocols above and below it in the stack.
In humans, and in all multicellular organisms, the complex task of thinking—in the sense of responding to our environment—is similar. Sensory input is collected, refined, and passed on to a decision making module, and the decision made is sent out to the various action takers: Muscles and secreting organs.
In addition to that complexity, there’s the complexity of multiple thinking processes going on inside people, most of them unconscious. For instance, your stomach and intestines have to decide how to digest food—which enzymes to secrete. That decision has nothing to do with the decisions involved in keeping your body’s balance while leaning across the restaurant table to take your date’s hand, or in looking into your date’s eyes, or in saying something to impress him or her. Whew! Complex, indeed!
However, this book considers only the part of the human Thinking Stack involved in conscious thinking that relates to voluntary decisions. That means concentrating on the input and output connected to the brain.
Single-celled organisms can respond to food sources, adapt to changing environmental conditions, and flee or shut down in some fashion when conditions get too harsh. Likewise, growing plants respond to their environments.
Neither single-celled organisms nor plants need brains for this. Why do animals have brains?
Brains make moving around work well for multicellular organisms. They provide quick communication between input sensors (touch, taste, smell, and muscle status in the simplest organisms, plus hearing and sight in organisms with ears and eyes) and motion activators (muscles) on what to do and where to go next, plus high-level coordination for the processes involved.
Brains are expensive. They are tricky to make and they consume lots of energy. For that reason some animals lose theirs when they are no longer needed. A baby barnacle, for instance, is a free-swimming tadpole-like creature. It has a brain. But when the barnacle attaches to something and becomes a stationary adult filter feeder, it resorbs its brain and does just fine without one.
Coordinating movement was the reason Mother Nature invented brains. The rational thinking that humans do with theirs is rich, rich dessert beyond that meat and potatoes function.
There is a widespread urban myth, about a century old, that humans use only 10% of their brains at any one time. This idea endures because it offers hope of developing extrasensory powers, or just improving our memory, concentration, and decision making capability. Those hopes are used to sell product—by entertainers and charlatans on the psychic end, and by lifestyle trainers with think-better techniques on the self-improvement end.
There is no truth to the myth.
The whole brain is very busy all the time. These days we have brain scans that show that clearly. And before we had brain scans we had the evidence of strokes. Strokes are devastating, and they happen when the brain gets damaged, usually because the blood flow to a region of the brain gets messed up for one reason or another. Has anyone ever said, “Oh, I had a stroke, but I’m OK because it happened in the ninety percent of my brain that I don’t use regularly”?
The human brain is high-performance, and it’s all used.
The human Thinking Stack can be characterized as having four layers: Reflex, Habit, Morality, and Judgment.
The Reflex layer is not in the brain at all, but mostly in the action areas, such as the muscles. This layer makes fast, simple responses to simple inputs such as muscle position and tension. When the doctor taps your knee, s/he’s changing the position of the knee tendon, your leg Reflex nerves sense the change and try to compensate by activating muscles, and all this happens without brain intervention.
Although Reflexes don’t happen in the brain, they are still very much a part of the Thinking Stack. Evidence includes the phenomenon of “phantom limb”: If an arm or a leg is amputated, the brain will quite often still “feel” sensation coming from that limb. The Thinking Stack is so strongly adapted to getting and sending messages from the lost limb that when real messages don’t come, some still intact part of the Reflex layer makes something up to send on to the rest of the nervous system.
Tinnitus, the “ringing in their ears” some people hear in very quiet places and/or when they lose some hearing, is similar. When no input is available, it gets fabricated.
Another example is Charles Bonnet Syndrome, visual hallucinations experienced by some legally blind people.
These all indicate that thinking is a body-wide activity.
Besides doing such thinking on its own, the Reflex layer also carries out simple commands sent from Habit, the next level of the stack.
Habit is the layer that tells the Reflex layer what to do. Once we decide at the conscious level to walk somewhere, then unless something is strange about where or how we’re walking, we hand off the details of how to get there to Habit, which tells Reflex what to do based on sensory input from sight, hearing, touch, and memory.
Next to Reflexes, Habit provides our fastest thinking. It can handle much more complicated tasks than Reflex can. When you are playing a sport, playing a musical instrument, or doing any other activity you know so well that you can “go with the flow”, you have engaged Habit thinking.
So is a telephone marketer who’s been reciting their script so long that they can think about something else as they talk. This is why such a person sounds sing-songy, different from the person who’s thinking about what they're saying.
Habit thinking is about automatic actions. Morality thinking is about actions that you’ve made up your mind on. So when the question comes up you do think about it, but you don’t have to think much. If you don’t have to think about it at all, then it’s become a Habit.
So if you turn right or left from the water fountain when you go to the office restroom, that’s a Habit. When you read the signs on the restroom doors at an unfamiliar restaurant before opening one, you’re invoking the “Men’s or Women’s?” decision in your Morality layer.
Note that in my usage, religion and/or ethics feed into some but not all Morality layer decisions! Morality covers a whole lot more.
Another example: When someone in the US asks you, “Are you a Democrat or a Republican?” you give the answer quickly and smoothly. (It may, of course, be “Neither!”)
Air traffic controllers, police dispatchers, and similar professions use Habit thinking most of the time on most days, but when an emergency comes up, Morality thinking engages.
Building up Morality thinking is the reason for public safety drills. The most widespread current examples in the U.S. are school fire drills, but earthquake drills, air-raid drills, etc., use the same principle. A real emergency comes rarely, but if people have practiced even a little over time, Morality thinking can take over, and getting to safety happens more rapidly, smoothly, and predictably.
The Judgment layer is the highest, most conscious layer. It makes new choices and learns how to do new things. Then Judgment trains Habit and Morality.
Judgment thinking can handle a wide variety of topics, but it is slow and clumsy and takes a lot of energy. So it’s easy to get tired and irritable when you have to use Judgment thinking for too long. But it’s the only level of the Thinking Stack that can handle new situations and come up with new ways of handling old situations.
To feel pure Judgment thinking in action, try doing something you haven’t done before.
Go ahead … take a moment and try it … try doing something new. I’ve listed some suggestions in the next couple paragraphs.
For some tasks where you’ll get significant help from your Habit and Reflex layers: Write your name several times with your off hand. Shovel snow or rake leaves or pitch hay for a while with your hands reversed (unless you habitually do so already to save your back). If you’re musical but not a pro, play a familiar tune on a familiar instrument in a different key.
Or for a more purely Judgment layer experience: Write this sentence with your off hand, or copy a sentence in an alphabet you don’t know. Make a comparatively easy move in a sport you’ve seen but don’t want to play—taking a tennis or golf swing, making a basketball free throw, whatever. Play an unfamiliar instrument and/or piece you dislike.
Do a novel project such as one of these for a little while, and notice:
If the new task were something you actually wanted to learn and do regularly in the future, Judgment would be screaming for Morality and Habit to take over and let it off the hook, which is what practicing a skill is all about. And as they took over, you’d do the tasks faster and better.