Thinking fast and slow in UX

We can all agree that our brains are sophisticated machines. They’re capable of handling enormous amounts of incoming linguistic information simultaneously processing complex visual patterns. However, even though our brains are powerhouses, they do sometimes get lazy. Most often than not, our brains don’t really want to think too hard or too much if they don’t need to. If there’s a cognitive path of least resistance, you can bet our brains will choose it. And most of the time we won’t even be aware of it happening! 

Thinking fast vs. thinking slow

Our brains tend to be described as using two systems. One conscious that we control and  one unconscious that we don’t. In order to distinguish these two systems Stanovich and West coined the terms, System 1 and System 2, which were later popularized by psychologist and Nobel laureate Daniel Kahneman in his best-selling book Thinking Fast and Slow.

System 1 can be called the ‘fast’ system. It allows us to make decisions with little-to-no effort. It’s completely unconscious and automatic, operating on associative processes. For example, rapid decision you make following your ‘intuition‘.

System 2 is the ‘slow’ system. It helps us make conscious and deliberate decisions that require rule based or logical reasoning. We use this system to, for example, choose the best car insurance provider.

Since we tend to be cognitive misers, we naturally prefer using System 1 over System 2, since it’s quicker, requires less effort and most of the time provides relatively decent outcomes. We usually don’t want to initiate System 2, unless we really have to. It’s cognitively demanding and generally creates a feeling of exhaustion. This is the principle of least effort.

We like arriving at solutions without exerting much effort. That’s why we like using products or services that help us reach desired goals without actually making us think too hard.

Think about it, we like using car insurance comparison websites to pick best options and we want those services to be as simple to use as possible.

Combining processing fluency with the principle of least effort

When our brains do get ‘lazy’, they tend to use shortcuts to arrive at the outcomes they’re required to produce. One such short cut is its reliance on processing fluency to produce judgments. For example, the simple act of perceiving an image can be characterized by features that are nonspecific to its concept, such as the speed (easiness) or accuracy of stimulus processing. Putting it simple, if you are met with a novel stimuli the easier it is to process it the more positively it can be evaluated.

Fluency feelings can arise from many different factors such as the ease of generating thoughts and accessing memories; as well as the ease of processing external stimuli. A variety of studies have shown that high vs. low fluency of processing influences peoples’ subjective judgments about the properties of the evaluated objects.

The easier it is to process a given stimuli the more positively it can be evaluated.

Song and Schwarz demonstrated how a simple fact of manipulating font type in a recipe, influences how people later evaluate and perceive it. In one of their studies the participants needed to read a recipe on how to make a Japanese sushi role. They either received it in Arial font (easy, standard to read) or in Mistral font (less common, difficult to read).


This was enough to influence their judgments. Participants in the ‘difficult’ condition evaluated the recipe as harder to do than did the participants in the ‘easy’ condition. Reported to be less likely to try to make it themselves. And what is even more fascinating, the person that would prepare the sushi roll needed to be highly skilled.

Understanding how low level features of objects impact our perceptions is a clear road towards creating user experiences that are perceived as seamless, due to being easy to use and not requiring unnecessary thought.

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