Thinking Slow About Thinking Fast – Part II


The idea that we are irrational stems from several observations where our decisions are inconsistent with those that would maximize gains. In other words, we often choose options that appear less beneficial than alternative options.

Though irrationality implies lack of logic or order, the behaviors we deem irrational actually have order and follow reliable patterns. Many animal species too display the same type of “irrational” behaviors that humans do, suggesting that the nature of our decision making may have evolutionary roots.

Daniel Kahneman recently described our decision making processes in his book Thinking Fast and Slow. Though many choices can rely on fast thinking, occurring almost automatically and requiring little attention, other decisions require slow, deliberative thinking. For example, when moving to a new house in an unfamiliar neighborhood, we have to pay attention to how to get to the house. We’ll likely follow directions or use a map, which requires focus.

Different parts of the brain mediate choices resulting from focused attention and those that are habitual. Slow thinking engages the prefrontal areas, which are evolutionarily newer parts of the brain and involved in executive functions, whereas fast thinking relies on deeper, more primitive brain structures.

With repetition, choices that once required slow thinking can come to rely on fast thinking. For instance, though learning the directions to our new house will require mental effort in the beginning, eventually we’ll be able to navigate to and from our home while conversing with others, singing along to music, or planning our day. As our drive home becomes automatic, or habitual, the deeper parts of our brains that mediate fast thinking will take over, freeing up the frontal areas to focus elsewhere.

Efficiency is therefore a significant benefit of habits. The downside to habits is their lack of flexibility. Once we’ve driven home from work hundreds of times, we may find ourselves on our normal route on a day when we were supposed to do a favor for a friend on the other side of town. Strong habits do not allow much incorporation of new information, and so our reliance on them does not always result in optimal outcomes.

Our behavior is a balance of slow thinking, which improves the likelihood of making optimal decisions, and fast thinking, which enhances our decision making efficiency. When we use our slow brain to analyze our choices, we identify behaviors that appear irrational because they are not the choices a purely slow brain would make. But given the benefit of efficiency, these choices are not particularly surprising.

As we go through a number of examples of our so-called irrational behavior, it should become apparent that our behavior is a reasonable product of a system balancing the goal of accuracy with the goal of practicality. That our choices are often “predictably irrational” suggests to me that, by some measure, these choices are the most valuable choices. This notion becomes more intuitive when we consider time and energy as innately valuable.

Image via CWB / Shutterstock.

Nisha Cooch, PhD

Nisha Kaul Cooch is a Senior Contributor for Brain Blogger and founder of BioInnovation Consulting LLC, a life sciences communications firm based in Washington DC. Dr. Cooch holds a PhD in neuroscience and specializes in the nature of decision making. You can follow her on Twitter @BioInnovationCo.
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