Interaction design (IxD) defines how people interact with products. It focuses on creating usable and enjoyable products that enable users to accomplish their tasks and goals seamlessly.
Good interaction design makes technology easier to use and it ensures products are intuitive and meet user needs which reduce their frustration by creating a smooth experience and increases their satisfaction, leading to increased engagement and higher retention rates. Additionally, effective interaction design increases efficiency as a result users can complete tasks faster and with fewer errors. And by prioritizing user-centered design, interaction design leads to better products. These products are more enjoyable, effective, and accessible for everyone. Research shows that well designed websites can increase conversions by up to 200% (Forrester Research).
In this article, we will explore the key interaction design principles that designers should consider when creating digital products and services, and how these principles can help to improve user experiences.
8 Principles of Interaction Design
With the Interaction design (IxD) principles, designers can build highly intuitive, recognizable interfaces that provide seamless experiences for users that prove a brand thoroughly understands them, their contexts and the goals they seek to achieve. Whether it’s mobile app design, web design or software, implementing Interaction design principles enhances usability and drives business growth.
Here are 8 key principles of Interaction Design to keep in mind;
1. Consistency:
Consistency means using similar operations and similar elements for achieving similar tasks such as using the same style for icons, colors, and fonts and buttons should always perform the same action. For example, if a website uses a blue “Submit” button for submitting forms, all forms across the site should have the same blue “Submit” button rather than a different color or style. As a result, users will quickly recognise and complete their work efficiently.
Poor consistency can increase the cognitive load as when there are different icons and different colours within the interface so they have to put extra mental effort in recognising and understanding. For example, if a shopping app uses a cart icon for “Add to Cart” on one page but a basket icon on another, users may struggle to identify the function quickly which can lead to confusion and inefficiency.
So it’s important for designers to use the same terminology for similar actions across the interface and test the designs with users as this will help to identify inconsistencies and improve usability by ensuring a seamless and intuitive user experience. Studies show that consistent UI design can improve user efficiency by up to 47% and reduce errors by up to 80%.
2. Affordance:
Afford means to give the cues to suggest the object’s function and it guides users on how to use a digital interface. Digital affordances include buttons that look clickable and icons that suggest their function. For example, a trash bin icon on a desktop suggests that users can drag and drop files into it to delete them. And text links that are usually blue and underlined. These visual cues help users understand how to interact with the design.
Whereas, poor affordances means when the interface elements don’t clearly show the meaning of it and when it is difficult to use like a hyperlink which looks like a text which makes the user unaware that it’s clickable. One more example is a form field without border or label which confuses users to where to put the input. Poor affordance can cause confusion and can frustrate the users. To avoid this, designers should use the familiar icons which are universally recognisable like a Trolley or Basket to add to cart and make buttons look clickable by using shadows, colours or borders as good affordances make interfaces intuitive and reduce the need for instructions which enhances user experience as interactions become more mature and efficient.
A study found that intuitive interfaces with strong affordances can reduce user errors by upto 50% and improve task completion time by up to 30%.
3. Feedback:
Feedback confirms user inputs instantly by responding to their actions in the form of visual changes, sounds, messages or animations. Providing timely feedback to user actions and creating responsive interactions are key elements of interaction design.
When users interact with an interface, they should receive clear and immediate feedback to confirm that their action was successful as there should not be any confusion in the mind of a user as to the state of the product, i.e., processing, loading, searching, uploading, etc., or some other state change. For example, a loading spinner indicates that a process is in progress, while a success message confirms that an action (like form submission) was completed successfully. As a result, usability will increase and when they know the current system status whether their task is completed or not so they won’t get frustrated or confused this keeps them stay focused and engaged as a result they are less likely to abandon the task if they know the system is responding.
A study found that clear and immediate feedback can improve user engagement by 30% and reduce task abandonment rates by up to 20%.
4. Visibility:
Basically, if the user cannot find it, it does not exist for them. And if more visible an element is, the more likely users will know about them and how to use them. Key aspects include clear labels, intuitive icons, and effective use of visual cues.
Important elements should be clear, obvious and users should quickly know what actions are possible without having to search or think. When the key elements are hidden and are not placed on the right side so users may get lost in the site leading to frustration and they may abandon the task. For example, The typical shopping cart abandonment rate for online retailers varies between 60% and 80%, with an average of 71.4%. As a result, it’s important that key elements should be easily discoverable as it reduces the effort to navigate or complete the task which reduces user errors and it also improves the overall user experience. For example, A “Buy Now” button should stand out with a bold color and large size.
5. Learnability:
Learnability measures how easy it is for users to learn to use a design. Designs with high learnability allow users to do basic tasks quickly. And it also allows them to learn to use the interface without much effort and gives them a sense of achievement so they feel smart and capable of grasping and utilizing newer interfaces.
When there is unclear navigation, inconsistent layouts and different icons for similar functions it becomes difficult for users to learn and they take longer to complete the task. So a learnable interface should provide users with clear instructions and guidance on how to use it. It should also use familiar design patterns and conventions so that users learn to use the interface in the first attempt and not face issues using it again. As it was found that users are 5 times more likely to complete a task if the design is easy to learn.
Additionally, learnability is often tested through user testing. These tests watch new users as they try to use the design. The goal is to find problems and fix them as fixing problems makes the design easier to learn for users.
6. Mapping:
Mapping is about having a clear relationship between controls and the effect they have on the world. Good mapping makes a product easy to understand and use. It creates a clear relationship between what a user does and what happens. For example, when you drive a car, when you turn the car steering wheel on the right side so the car moves right and when you turn on the left side so it turns to the left side.
Poor mapping may not match user expectations or real-world actions so users may struggle to understand how to use the interface so this issue can result in reduced efficiency and satisfaction which can lead to poor usability. And when there is not a clear relationship between control and effect so users may make errors and it will take longer for them to complete the task For example, a slider for adjusting volume that moves vertically instead of horizontally can confuse users because it does not align with common expectations. Similarly, poorly placed light switches that do not correspond to the right lights can cause frustration.
As a result, designers should consider mapping to make technology more user-friendly, intuitive and efficient as clear and effective mapping allows users to complete their task quickly as they know how the interface works and responds to their action so they become more confident in using the interface as they understand the system. This leads to smoother user experience and increased satisfaction so they are more likely to return and engage with the system again. According to study by Forestor, a well-designed user interface can increase conversion rates by up to 200%, while a better UX design can boost conversion rates by 400%. This shows that businesses investing in intuitive and seamless app experiences can significantly outperform competitors.
7. Constraints:
It limits the users actions to prevent the errors and guide them towards the correct way. For example, a dropdown menu with predefined choices prevents users from entering incorrect data and a grayed-out button indicates an unavailable action, which reduces confusion. And by limiting the options, constraints reduce the cognitive load as a result, users feel more satisfied which leads to better user experience and constraints also make the interface intuitive and more user friendly.
A study by HubSpot found that websites with constrained interfaces (e.g., limited navigation options) had higher engagement rates (up to 22% increase) compared to those with unconstrained interfaces.
8. Conceptual Models and Mental Models:
A conceptual model is how designers want users to understand a system. It’s the planned user experience. And mental models are how users actually understand the system. These models are based on experience.
Conceptual models are the intended design. They show key concepts and relationships. Designers use metaphors and analogies in conceptual models which helps users learn the system. Also, designers can find the issues early which prevents problems. Whereas, mental models form as users interact with a product. Users create their own understanding and products match how users expect them to work which improve user satisfaction and they make fewer mistakes when using the product.
Mismatch between these models can cause problems like users may feel confused and they might make mistakes if designers must research user expectations. This makes the system easier to learn and also user testing is important to refine the conceptual model. This ensures it matches how users think. When users’ mental models align with the conceptual models, they develop a deeper understanding of the product, leading to increased proficiency and reduced cognitive load. As 95% of users say that a positive user experience is the most important factor when interacting with a website or application.
Fundamental interaction design principles will always play a central role in the design of future systems and it’s important for designers to keep them in mind because well designed interfaces not only makes a product easier to use but also boosts the user satisfaction and business success. Research shows that investing in good UX can increase conversion rates by up to 400%,proving that thoughtful interaction design is not just about usability but also about business growth.
So make sure to understand these 8 principles of Interaction design so that you can create user-centered and effective digital experiences. Ready to create seamless and engaging user experiences? Start applying these 8 principles of interaction design to your next project. Conduct user testing, gather feedback, and refine your design to ensure it meets users’ needs and expectations.
