Why two speeds?
Well, to make the best use of our limited capacity to pay attention, the brain needs to be able to quickly sift through reality and spare energy most of the time. That way, resources are available when circumstances require deep thinking.
That does not sound like there is much wisdom to spare. True. But here is the cost-benefit of each speed.
The brain ‘mode’ that tends to use shortcuts and autopilot is what Daniel Kahneman calls “thinking fast”. It’s goal is to allow us to get by, quickly, without having to process the environment in great details.
Thinking-slow, on the contrary is the more expansive, more effortful and analytical problem solving 'mode'.
This autopilot mode occurs when driving on a familiar route. When the road is familiar and the behaviour has been repeated many times, the brain can effortlessly ‘drive itself home’, with very little conscious involvement or effort (which can sometimes result in not even remembering the event).
Fast-thinking is about...
If we attempted to process all aspect of every moments of everyday...
Our brains would overload and crash.
2. Ignoring unfamiliar information.
To avoid having to come up with a whole new model of reality
every 5 minute.
3. Ignoring unnecessary information.
Anything that does not help to perform the task at hand is blinded.
4. Prioritising, above all.
Allows us to move forward (and survive) in the face of the
mesmerising complexity of our environment.
The auto pilot tends to works like a spam folder that operates below consciousness.
When the brain does not simplify?
A more deliberate type of thinking takes place. This analytical mode is a slower, deeper and demands more energy. It allows us to process the environment with greater care and reliability, a good example is any sort of problem solving.
While deep thinking is an energetic cost, thinking fast comes at an accuracy expense. As a result, although we can let our brain pilot the car, our attention is quickly reconnected if anything unexpected or in habitual comes up.