Psychology in Design

Isolation Effect

The Isolation Effect (also known as the Von Restorff Effect) is the tendency to recall something that stands out in a group and afford it more weighting than its peers.

Items that stand out from their peers by color, shape, position, size, and texture are more memorable.

Serial Position Effect

The Serial Position Effect (also known as Primacy and Recency effects) is a psychological phenomenon associated with memory. It says that items at the beginning (primacy) and items at the end (recency) of a list or string of information are more easily recalled than items in the middle.

Graph showing the U-shaped serial position curve to the left and practical example to the right

The first item in a list is initially distinguished from previous activities as important (primacy effect) and may be transferred to long-term memory. You remember it because that is where you started.

Items at the end of the list are still in short-term memory (recency effect). You remember the end the best.

While items in the middle will suffer the worst recall. Just like on the graph: The more to the middle, the worst recall it will have.

Zeigarnik effect

The Zeigarnik Effect is the tendency to experience intrusive thoughts about an objective that was once pursued and left incomplete. The automatic system signals the conscious mind, which may be focused on new goals, that a previous activity was left incomplete.

Examples of how to make a use of Zeigarnik effect

Zeigarnik effect says that people remember uncompleted or interrupted tasks better than completed tasks.

Picture Superiority Effect

The Picture Superiority Effect, or pictorial superiority effect refers to the phenomenon in which pictures and images are more likely to be remembered than words.

Example of Picture Superiority Effect

Experiments shown that in human memory recall, pictures outperform text dramatically. When information is presented orally, after 3 days, people will only remember 10% of it.

Category Size and Typicality Effects

The Category Size Effect says that people respond faster when the item is a member of a small category (eagle is a bird vs eagle is an animal). And the Typicality Effect says that people are faster to respond to usual or typical members. For example, when asked to name a bird an individual is much more likely to respond with robin instead of a penguin.

Example of Category Size effect

Category Size and Typicality Effects in cognitive neuroscience were mainly based on several ERP studies. Both effects comes from Semantic processing which is the processing that occurs after we hear a word and encode its meaning. Semantic processing causes us to relate the word we just heard to other words with similar meanings. Once a word is perceived, it is placed in a context mentally that allows for a deeper processing.

Simon and Stroop effects

Simon Effect refers to the finding that reaction times are usually faster, and reactions are usually more accurate, when the stimulus occurs in the same relative location as the response, even if the stimulus location is irrelevant to the task. While Stroop effect occurs when a behavior or skill no longer requires direct interaction, cognitive psychologists say it is automatized.

In other words, when you first learned to tie your shoelaces, you needed to think carefully through each step of the process. Now, you probably do not even think about the steps, but simply initiate a series of movements that proceed without any further influence.


Schema theory states that all knowledge is organized into units. Within these units of knowledge, or schemata information provided by life experiences is stored. According to this theory, schemata represent knowledge about concepts: objects and the relationships they have with other objects, situations, events, sequences of events, actions, and sequences of actions.

Schemas affect what we notice, how we interpret things and how we make decisions and act. People are more likely to notice things that fit into their schema. They act as filters, accentuating and downplaying various aspects of interaction with the world. They also help to forecast, predicting what will happen. We even remember and recall things via schemas, using them to “encode” memories.

The schema has a tendency to remain unchanged, even in the face of contradictory information. Once we have created or accepted a schema we will fight hard to sustain it.

Functional Fixedness

This cognitive bias limits a person to use an object only in the traditional manner. In other words, it is a mental block against using an object in a new way.

For example, if someone needs to stop unplugging extension cords, they may not see that these cords can be tied together to solve the problem. The same thing touches the design of the interface. A not obvious function of the component will be almost never noticed by the user.

Functional fixedness is a bias that strengthens over time. The more we get to used to use an object in one way, the harder it is to see and use alternative ways.

Hick’s law

Hick’s law describes how increasing the number of choices will increase the decision time logarithmically, in other words, the more alternatives you have, the longer you take to make a choice, and the more likely you’ll experience information overload.

Example: The more options the harder to choose the payment method

By using Hick’s Law, we should create designs which reduce information overloading by reducing the number of alternative choices in places critical for decision making.

Fitts’s law

Fitts’s law is a scientific law that predicts that the time to acquire a target is a function of the distance to and size of the target.

As the distance to the object increases, the movement takes longer. And as the size of the object decreases the selection again takes longer. So, if you make a small component 20% larger, it will become much more clickable, but if you make an already very large button 20% larger, you will not gain much more in terms of its usability.

Therefore reducing the distance from one point to the next and making the target object large enough to enable prompt detection and selection of interactive components without sacrificing accuracy, as well as ensuring that users are able to click anywhere on an interactive component increases the usability of the user interface.

Bizarreness and Priming effects

The bizarreness effect holds that things associated with bizarre images or phrases are more readily recalled than those associated with common images or phrases.

Priming effect is an aspect of cognitive psychology that explains how exposure to a stimulus activates a concept in memory that is then given increased weight in subsequent judgment tasks. Priming works by making the activated concept accessible so that it can be easily used in the evaluation of related objects. Visual priming works best with visual cues. For example, text about software engineers is recognized more quickly following the related image.

Halo effect

The tendency in which our impression about the part of the whole can be influenced by our overall impression of the whole by using evaluations based on things unrelated and transferring them from one attribute to other.

For example, an attractive person using a mental heuristic will be perceived as being intelligent and reliable, even though there is no rational reason to believe that appearance corresponds with intellect and dignity.

Halo effect influence many objects, and interfaces are not an exception. If the interface has more aspects to like than dislike and if these aspects are seen first or are important for users, then they are more likely to judge it favorably about the interface as the whole. Conversely, if users have a particularly bad experience with the interface, they’ll predict that they’ll have the same bad experience in the future, carrying over their negative expectations from their earlier experience. The halo effect works in both positive and negative directions. So, let’s put it simple — impression matters.

Courtsey: Andri Budzinskiy