Psychological research applied to interface design

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A better understanding of user psychology results in better product design. Here are key principles and how they apply to design.

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While most people might think of design as a creative field, there’s a lot of science behind website design that is effective and draws people in.

A lot of design science is rooted in psychological concepts, theories, and even “tricks” that turn an aesthetic idea into something truly functional. These psychological design principles help convert everyday website visitors into loyal brand followers and online shoppers, who engage with the website.

Psychological knowledge can include elements such as color and typography, but also extend to the way you present information, including messaging and user interface functionality. Here are some key psychological findings, and how they can be applied to website or app design:

The Von Restorff effect and focal points

The distinct visual element will be the ones that website visitors remember the most and interact with first. The Von Restorff effect, or the isolation effect, is the basis for creating a focal point in every scroll or screen in a design.

Uniquely different elements – due to their contrast, color, size, shape, or spacing – will stand out in the design, making an impact that's both immediate and long-lasting.

Key actions or information should be visually distinctive so that people will remember them more.

The original experiment behind the theory was conducted by a German psychiatrist and pediatrician, Hedwig von Restorff. It has since been replicated in various other studies to evaluate the effectiveness of everything from marketing pieces to design. The innovative 1933 study found that when participants were presented with many similar items and one distinctive, isolated item, memory for the singular item was improved.

This paradigm can have broad application in website and app design. Consider elements such as pop-ups or notifications; by making their design stand in contrast to the rest of the website, you can potentially draw more attention to your message. Furthermore, this sort of interference will be better remembered and could help keep users on your design longer, resulting in an increase in click-through or conversion rates.

Another familiar application of the Von Restorff effect is going with a color that's different from the overall color scheme for your call-to-action buttons. By use of differentiation, the design can direct a spotlight on the button and its functionality.

The Von Restorff effect: When multiple similar objects are present, the one that differs from the rest is most likely to be remembered.

Hick’s law and limited choice

Most clients love to have a plethora of choices available on their websites – mega menus, multiple places to click, buttons everywhere, and some added notifications.

While it’s a commonly held view that one of these elements will result in a conversion, the reality is that an overwhelming design can actually have a negative impact on website visitors.

Instead of laying out all options at once, consider a this-or-that strategy so that users only have to make a single choice at a time. Breaking actions into smaller steps or processes can make for a much friendlier user journey.

Hick’s law, also known as the Hick-Hyman law, was developed by William Edmund Hick and Ray Hyman in the 1950s. It's explained by a mathematical formula:

RT = a + b log2(n)

Where RT is reaction time, n is the number of choices, and a and b are other measurable constraints. This proves that the more choices you have, the longer it takes to act, which can potentially lead to inaction.

Fun fact: The K.I.S.S. (keep it simple, stupid) theory that we all know evolved from Hick’s law, even it if did originate with the U.S. Navy.

Hick’s law applies to many of the usability standards associated with modern design such as offering a this-or-that option in a split-screen aesthetic, or asking for only an email address in a sign-up form.

Hick’s law: The time it takes to make a decision increases with the number and complexity of choices.

Gestalt principles and visual weight

There are five main principles of shape, space, and perception that drive how designers work with layers, contrast, and the positioning of elements.

Even if you aren’t consciously applying the rules of Gestalt psychology developed by Max Wertheimer, Wolfgang Köhler and Kurt Koffka in the 1930s and 40s, they’re probably evident in your work.