In the age of AI and Human-Centered Machine Learning, it’s essential that we understand the needs and behaviour of our users.

Simply put, it is how users feel when they use a product. Is it easy to use? Does it get the job done to their satisfaction?

In order to create work that better serves the needs of our users, it’s important to understand some basic psychological principles. There are a lot of laws of UX some of the basic ones are:

"Faster to hit larger targets closer to you than smaller targets further from you."

In 1954, psychologist Paul Fitts, examining the human motor system, showed that the time required to move to a target depends on the distance to it, yet relates inversely to its size. By his law, fast movements and small targets result in greater error rates, due to the speed-accuracy trade-off. Although multiple variants of Fitts’ law exist, all encompass this idea. Fitts’ law is widely applied in user experience (UX) and user interface (UI) design. For example, this law influenced the convention of making interactive buttons large (especially on finger-operated mobile devices)—smaller buttons are more difficult (and time-consuming) to click. Likewise, the distance between a user’s task/attention area and the task-related button should be kept as short as possible.
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Fitts's Law: The Importance of Size and Distance in UI Design
​​​​​​​Fitts's Law on Wikipedia

"The time it takes to make a decision increases with the number and complexity of choices."

Hick’s Law (or the Hick-Hyman Law) is named after a British and an American psychologist team of William Edmund Hick and Ray Hyman. In 1952, this pair set out to examine the relationship between the number of stimuli present and an individual’s reaction time to any given stimulus. As you would expect, the more stimuli to choose from, the longer it takes the user to make a decision on which one to interact with. Users bombarded with choices have to take time to interpret and decide, giving them work they don’t want.

Hick’s Law - Quick Decision Making 

"Users spend most of their time on other sites this means that users prefer your site to work the same way as all other sites they already know.”

Jakob's Law was coined by Jakob Nielsen, a User Advocate and principal of the Nielsen Norman Group which he co-founded with Dr. Donald A. Norman (former VP of research at Apple Computer). Dr. Nielsen established the 'discount usability engineering' movement for fast and cheap improvements of user interfaces and has invented several usability methods, including heuristic evaluation.

“People will perceive and interpret ambiguous or complex images as the simplest form(s) possible.”

In 1910, psychologist Max Wertheimer had an insight when he observed a series of lights flashing on and off at a railroad crossing. It was similar to how the lights encircling a movie theater marquee flash on and off. To the observer, it appears as if a single light moves around the marquee, traveling from bulb to bulb, when in reality it’s a series of bulbs turning on and off and the lights don’t move it all. This observation led to a set of descriptive principles about how we visually perceive objects. These principles sit at the heart of nearly everything we do graphically as designers.
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"Elements that share similar characteristics are perceived as more related than elements that don't share those characteristics.”

The human eye tends to perceive similar elements in a design as a complete picture, shape, or group, even if those elements are separated. The brain seems to craft a link between elements of a similar nature. Then, we perceive them in a relationship with each other, separating them from other elements in a design. Human eyes are good at filling in “gaps” or connecting “dots”. It happens naturally.​​​​​​​
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The Law of Similarity - Gestalt Principles

"Objects that are closer together are perceived as more related than objects that are further apart.”

The principles of grouping (or Gestalt laws of grouping) are a set of principles in psychology, first proposed by Gestalt psychologists to account for the observation that humans naturally perceive objects as organized patterns and objects, a principle known as Prägnanz. Gestalt psychologists argued that these principles exist because the mind has an innate disposition to perceive patterns in the stimulus based on certain rules. These principles are organized into five categories: Proximity, Similarity, Continuity, Closure, and Connectedness.

"The average person can only keep 7 (plus or minus 2) items in their working memory."

In 1956, George Miller asserted that the span of immediate memory and absolute judgment were both limited to around 7 pieces of information. The main unit of information is the bit, the amount of data necessary to make a choice between two equally likely alternatives. Likewise, 4 bits of information is a decision between 16 binary alternatives (4 successive binary decisions). The point where confusion creates an incorrect judgment is the channel capacity. In other words, the quantity of bits which can be transmitted reliably through a channel, within a certain amount of time.
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The Most Important Rule in UX Design that Everyone Breaks​​​​​​​

"The Pareto principle states that, for many events, roughly 80% of the effects come from 20% of the causes."

Its origins stem back to Vilfredo Pareto, an economist who noticed 80% of Italy’s land was owned by 20% of the population. Though it might seem vague, the 80/20 way of thinking can provide insightful and endlessly applicable analysis of lopsided systems, including user experience strategy.

"Any task will inflate until all of the available time is spent."

Articulated by Cyril Northcote Parkinson as part of the first sentence of a humorous essay published in The Economist in 1955 and since republished online, it was reprinted with other essays in the book Parkinson's Law: The Pursuit of Progress (London, John Murray, 1958). He derived the dictum from his extensive experience in the British Civil Service.
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"The Serial Position Effect is the propensity of a user to best remember the first and last items in a series."

The serial position effect, a term coined by Herman Ebbinghaus, describes how the position of an item in a sequence affects recall accuracy. The two concepts involved, the primacy effect and the recency effect, explains how items presented at the beginning of a sequence and the end of a sequence are recalled with greater accuracy than items in the middle of a list. Manipulation of the serial position effect to create better user experiences is reflected in many popular designs by successful companies like Apple, Electronic Arts, and Nike.
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The Serial Position Effect: Why ABC and XYZ Stand Out the Most Among All the Alphabets. ​​​​​​​

"When multiple similar objects are present, the one that differs from the rest is most likely to be remembered.”

The theory was coined by German psychiatrist and pediatrician Hedwig von Restorff (1906–1962), who, in her 1933 study, found that when participants were presented with a list of categorically similar items with one distinctive, isolated item on the list, memory for the item was improved.
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"People remember uncompleted or interrupted tasks better than completed tasks."

Bluma Wulfovna Zeigarnik (1900 – 1988) was a Soviet psychologist and psychiatrist, a member of the Berlin School of experimental psychology and Vygotsky Circle. She discovered the Zeigarnik effect and contributed to the establishment of experimental psychopathology as a separate discipline in the Soviet Union in the post-World War II period. In the 1920s she conducted a study on memory, in which she compared memory in relation to incomplete and complete tasks. She had found that incomplete tasks are easier to remember than successful ones. This is now known as the Zeigarnik effect. She later began working at the Institute of Higher Nervous Activity which is where she would meet her next big influence Vygowski, and become a part of his circle of scientists. It was also there that Zeigarnik founded the Department of Psychology. During that time, Zeigarnik received the Lewin Memorial Award in 1983 for her psychological research.
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The Zeigarnik Effect: Why it is so hard to leave things incomplete​​​​​​​