The Two Systems of Cognitive Processes

In today’s excerpt – thanks to the work of Daniel Kahneman and others, we now increasingly view our cognitive processes as being divided into two systems. System 1 produces the fast, intuitive reactions and instantaneous decisions that govern most of our lives. System 2 is the deliberate type of thinking involved in focus, deliberation, reasoning or analysis – such as calculating a complex math problem, exercising self-control, or performing a demanding physical task.

System 2 activities – cognitive, emotional, or physical – draw at least partly on a shared pool of mental energy. Studies consistently show that when the brain is occupied with one type of System 2 thinking, it interferes with any other type of System 2 thinking you need to perform at the same time. And performing one type of System 2 thinking makes us less able to perform a subsequent System 2 activity in the period immediately afterward – even if one is physical and the other is cognitive or emotional. Furthermore, when the mind is actively focused on a System 2 activity, it results in System 1 having greater influence over our behavior:

“It is now a well-established proposition that both self-control and cognitive effort are forms of mental work. Several psychological studies have shown that people who are simultaneously challenged by a demanding cognitive task and by a temptation are more likely to yield to the temptation. Imagine that you are asked to retain a list of seven digits for a minute or two. You are told that remembering the digits is your top priority. While your attention is focused on the digits, you are offered a choice between two desserts: a sinful chocolate cake and a virtuous fruit salad. The evidence suggests that you would be more likely to select the tempting chocolate cake when your mind is loaded with digits. System 1 has more influence on behavior when System 2 is busy, and it has a sweet tooth.

“People who are cognitively busy are also more likely to make selfish choices, use sexist language, and make superficial judgments in social situations. Memorizing and repeating digits loosens the hold of System 2 on behavior, but of course cognitive load is not the only cause of weakened self-control. A few drinks have the same effect, as does a sleepless night. The self-control of morning people is impaired at night; the reverse is true of night people. Too much concern about how well one is doing in a task sometimes disrupts performance by loading short-term memory with pointless anxious thoughts. The conclusion is straightforward: self-control requires attention and effort. Another way of saying this is that controlling thoughts and behaviors is one of the tasks that System 2 performs.

“A series of surprising experiments by the psychologist Roy Baumeister and his colleagues has shown conclusively that all variants of voluntary effort – cognitive, emotional, or physical – draw at least partly on a shared pool of mental energy. Their experiments involve successive rather than simultaneous tasks.

“Baumeister’s group has repeatedly found that an effort of will or self-control is tiring; if you have had to force yourself to do something, you are less willing or less able to exert self-control when the next challenge comes around. The phenomenon has been named ego depletion. In a typical demonstration, participants who are instructed to stifle their emotional reaction to an emotionally charged film will later perform poorly on a test of physical stamina – how long they can maintain a strong grip on a dynamometer in spite of increasing discomfort. The emotional effort in the first phase of the experiment reduces the ability to withstand the pain of sustained muscle contraction, and ego-depleted people therefore succumb more quickly to the urge to quit. In another experiment, people are first depleted by a task in which they eat virtuous foods such as radishes and celery while resisting the temptation to indulge in chocolate and rich cookies. Later, these people will give up earlier than normal when faced with a difficult cognitive task.”