6 psychological principles that every UX/UI designer should know

Understanding the psychology behind what motivates users to take (or not take) certain actions on a site is the backbone of good UX/UI design and, ultimately, increasing your business’ ROI. 

Without further ado, let’s take a look at some of the basic psychological principles to take into consideration when designing your landing pages – concepts cover informational processing, memory, and cognitive biases.

1. Choice Overload

Also known as ‘Hick’s Law’ and closely related to ‘decision fatigue’, this principle tells us that providing consumers with too many options is a bad thing, it makes it more difficult for consumers to make a decision. This phenomenon is known as ‘analysis paralysis’, where the user overthinks their choice which impedes their decision-making ability. This creates friction in the user journey and increases the chance that the user abandons the user journey altogether. 

On the other end of the spectrum, the user can make a decision too quickly and, in the face of too many choices, regret the decision later thinking that they could’ve made a better purchasing decision.

The solution is to limit the number of choices available to consumers or if that’s not possible, present them hierarchically with the preferred conversion path made larger, more obvious, and the most intuitive. CRO best practice generally advises not to provide more than 6-7 choices in one viewport; this includes everything from thumbnails on a shopping page to items in a navigation bar.

2. Cognitive Load

This principle tells us that an overload of information and stimuli detracts from a user’s ability to process information and, ultimately, increases the likelihood of users abandoning the journey altogether. Similar to USB sticks and hard drives, humans have a limited working memory and beyond that, information is simply not stored or is forgotten.

Human attention is a finite resource when aiming to drive conversions. In order to use it wisely, there are a number of steps that you can take:

  1. Don’t be original: In this case, originality is counterproductive. By relying on existing mental models (read: expected/normal layouts), you are minimizing the amount of learning a user needs to take on your website and therefore, you are clearing storage space in the user’s mind for the valuable content that fills your page.
  2. Have a visual clear out: Visual clutter is anything that doesn’t add value in helping your users make decisions. Whether it’s unnecessary images, excessive links, or overly flamboyant text, if it doesn’t add value, get rid of it.
  3. Minimize tasks: Automate as much as possible, so that your user has to do as little as possible. Too much work will deter your user – the easier, the better.

3. The Stand-Out Effect

The black sheep, the odd one out, the misfit, the exception to the rule – it’s undeniable that when something doesn’t fit into a pattern, it grabs our attention. In psychology, this is referred to as the Von Restorff effect. By simply making the product or CTA that you are trying to draw your users’ attention to visually different from the other elements on the page, your conversion rate will automatically improve.

4. The Psychology of Persuasion

In CRO, the psychology of persuasion can be broken down into two parts – reciprocity and authority:

  • Reciprocity: If you’ve ever wondered why so much free content is available online these days, the law of reciprocity probably has something to do with it. For example, by giving you a free trial, businesses and entrepreneurs are subconsciously making you feel indebted to them and you are therefore more likely to offer up your email address, or maybe even make a purchase once the free trial has finished. 
  • Authority: With so much information on the web, it’s no surprise that we’re looking for signals of what is trustworthy and credible. Adding in symbols of authority, such as titles (Dr., CEO., etc.) as well as associations with well-established rating sites (e.g. Trustpilot) or institutions (e.g. Harvard) establishes a certain level of trust that influences users to make a purchasing decision. 

5. Serial Position Effect

This psychological phenomenon, coined by Herman Ebbinghaus, entails two principles (the primacy effect and the recency effect) that tell us we are most likely to remember the first and the last items in a series. This principle is manipulated by the biggest brands all over the world to make sure we remember the most profitable items the most. Take Google search, for example. Have you ever wondered why it is the first and last results on a search page that are reserved for the highest bidding paid ads?

6. Gestalt Theory of Visual Perception

The Gestalt theory of visual perception encompasses a range of visual principles explaining that we perceive individual objects differently (and sometimes together) based on how they are spaced apart:

  • Proximity: When objects are grouped closely together, they are perceived as a whole
  • Similarity: When individual objects are very similar, they are perceived as one
  • Closure: When an object is unfinished/unconnected, the mind will mentally fill in the gaps and unify it together as one
  • Symmetry: Symmetry is visually appealing and the human mind tends to see imperfect symmetry as symmetry all the same
  • Figure and ground: The arrow in the ‘Ex’ part of the Fed-Ex logo makes use of this concept: this theory explains the way that users differentiate between the foreground and background of an object, and how both spaces are valuable for creating meaning
  • Continuity: This concept is often achieved through curved lines, and compels our eyes to move from one object to another by following lines


Applying some or all of these psychological principles to your UX/UI design is a surefire way to increase your conversion rate as well as your ROI.