As humans, we have an underlying "blueprint" for how we perceive and process the world around us, and the study of psychology helps us define this blueprint. As designers, we can leverage psychology to build more intuitive, human-centered products and experiences. Instead of forcing users to conform to the design of a product or experience, we can use some key principles from psychology as a guide for designing how people actually are.

Colors are the beautiful things that helps people to identify and differentiate similar objects. Psychologically, colors are what drive humans with emotions. A human mind perceive or create colors using the visual system of the brain, which means colors are subjective in nature instead of objective.

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Imagine going to a restaurant and choosing from a menu of over 100 items. Reading through all the available options is going to take longer time than choosing from the selected 20 items. Same goes with designing.

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Hick's Law. Hick's Law predicts that the time it takes to make a decision increases with the number and complexity of choices available. It was formulated by psychologists William Edmund Hick and Ray Hyman in 1952 after examining the relationship between the number of stimuli present and an individual's reaction time to any given stimulus.
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Miller's Law, which predicts that the average person can only keep 7 (± 2) items in their working memory. It originates from a paper published in 1956 by cognitive psychologist George Miller, who discussed the limits of short-term memory and memory span. Unfortunately there has been a lot of misinterpretation regarding this heuristic over the years, and it's led to the "magical number seven" being used to justify unnecessary limitations (for example, limiting interface menus to no more than seven items).

Jakob's Law (short for Jakob's Law of Internet User Experience), which states that users spend most of their time on other sites, and they prefer your site to work the same way as all the other sites they already know. In 2000, it was put forth by usability expert Jakob Nielsen, who described the tendency for users to develop an expectation of design patterns based on their cumulative experience from other websites.

A mental model is what we think we know about a system, especially about how it works. Whether it's a website or a car, we form models of how a system works, and then we apply that model to new situations where the system is similar. In other words, we use knowledge we already have from past experiences when interacting with something new.