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Saloni Goyal
Saloni Goyal

Posted on • Updated on

Cognitive Ease and Illusions of Truth

I can claim that I know what I am thinking at any given time, but I don’t really know how my brain works. How does a simulation in the environment traverses through my neurons and somehow starts a chain reaction of thoughts, emotions and actions.

System 1 and System 2

Human brain can be thought of as comprising of two subsystems: System 1 and System 2. System 1 is the fast, intuitive decision maker and System 2 is the slow and deliberate one. When someone says the word banana, I immediately think of a banana without any intent to do so. It is an automatic response and this is System 1’s doing. However, if I am asked what 23 times 18 is, it will take me some effort to come up with the correct answer.

2 Systems

System 1 takes care of intuitions and impressions but it cannot do difficult multiplication. System 2 needs to use its active resources and devote effort to actually get the calculation done and get a response. But human brain is lazy. It will always look for an intuitive, quick response before getting to work and if this spontaneous search for intuitive solution fails, I find myself switching to a slower, more deliberate and effortful form of thinking.

Laziness is the reluctance to invest more effort than is strictly necessary.

Cognitive Ease

Throughout the day, multiple computations are running in my brain which access and update answers to some key questions:

  • Is anything new going on?
  • Is there a threat?
  • Are things going well?
  • Should my attention be redirected?
  • Is more effort needed for this task?

These assessments are carried out automatically by System 1, and one of their task is to determine whether extra effort is required from System 2. System 1 keeps check of cognitive ease ranging from “Easy” to “Strained”.


Easy is when things are going well — no threats, no major change, no need to redirect attention or mobilize efforts. Strained is when System 2 needs to be engaged and take charge of the wheel.

Ease and Mood


When I am in a state of cognitive ease, I tend to be in a good mood, like what I see, believe what I hear, trust my gut and drop my vigilance. Cognitive ease makes me feel that my current situation is comfortably familiar. When I feel strained, I am more likely to be vigilant and suspicious, invest more effort in what I am doing, feel less comfortable, and make fewer errors, but I also am less intuitive and less creative than usual.

The experience of familiarity has a simple but powerful quality of ‘pastness’ that seems to indicate that it is a direct reflection of prior experience. This quality of pastness is an illusion.


Illusions of Truth

Predictable illusions inevitably occur if a judgment is based on an impression of cognitive ease or strain. Anything that makes it easier for System 1 to run smoothly will also bias beliefs. A reliable way to make people believe in falsehoods is frequent repetition, because familiarity is not easily distinguished from truth.

Good mood, intuition, creativity, gullibility, and increased reliance on System form a cluster. At the other pole, sadness, vigilance, suspicion, an analytic approach, and increased effort also go together.

A happy mood loosens the control of System 2 over performance: when in a good mood, people become more intuitive and more creative but also less vigilant and more prone to logical errors. Here, the connection makes biological sense. A good mood is a signal that things are generally going well, the environment is safe, and it is all right to let one’s guard down. A bad mood indicates that things are not going very well, there may be a threat, and vigilance is required.

Cognitive ease is both a cause and a consequence of a pleasant feeling and link between positive emotion and cognitive ease in System 1 has a long evolutionary history.


Psychologists believe that all of us live much of our life guided by the impressions of System 1 — and we often do not know the source of these impressions. How do I know that a statement is true?

  • If it is strongly linked by logic or association to other beliefs or preferences I hold, or
  • comes from a source I trust and like,

I will feel a sense of cognitive ease. The trouble is that there may be other causes for this feeling of ease and I have no simple way of tracing my feelings to their source.

The sense of ease or strain has multiple causes, and it is difficult to tease them apart.

Difficult, but not impossible. On most occasions, the lazy System 2 will adopt the suggestions of System 1 and march on. However, I can overcome some of the superficial factors that produce illusions of truth when strongly motivated to do so.


Top comments (1)

isherwood profile image
Clint Buhs

Nicely done. ♡ just for using "comprise" correctly. :)