Reduce complexity

Purchase decisions occur under varying conditions—focused or distracted, rested or exhausted. The question is: How does mental load influence decision quality, what types of errors emerge under pressure, and what evidence exists on this topic?

Studies

The Chocolate Cake Experiment

Baba Shiv and Alexander Fedorikhin conducted a groundbreaking experiment on cognitive load in 1999. They asked 165 Stanford University students to memorize either a simple 2-digit or a difficult 7-digit number. As participants walked down the hallway to the next room, they were offered a choice between chocolate cake and fruit salad. When memorizing the simple number, 59% chose the healthy fruit salad. However, when memorizing the 7-digit number, the ratio completely reversed: 63% opted for the cake. Remarkably, even this minimal mental load was sufficient to impair self-control.

Depleted Self-Control

In 1998, Roy Baumeister and his team conducted the famous "radish experiment," which demonstrated the limits of willpower. They placed hungry students in a room filled with freshly baked, fragrant chocolate chip cookies. Half the participants were allowed to eat the cookies, while the other half had to eat bitter radishes and completely resist the tempting cookies. Afterward, all participants were asked to solve an unsolvable puzzle. The results were striking: the radish group gave up after just 8 minutes, while the cookie group persisted for 19 minutes. Resisting the cookie temptation had depleted the radish group's mental energy so much that they had nothing left for further effort.

When the fact-check fails

Daniel Gilbert from Harvard demonstrated how cognitive load undermines our ability to verify truth. He presented test subjects with statements about a fictitious language on a computer, followed by labels indicating "true" or "false." Half of the participants were simultaneously required to retain a complex tone rhythm in their minds. Without this distraction, subjects correctly identified false statements 78% of the time. With the additional mental task, accuracy dropped dramatically to just 55%—barely better than random guessing. The experiment reveals a critical insight: Under cognitive load, we initially believe everything we encounter.

Principle

Which principle for Customer Experience Design can be derived from this? The principle of cognitive ease states that customers make better and more thoughtful decisions when the decision-making process requires minimal mental effort. Complex navigation, unclear information architecture, or cluttered interfaces force the brain to expend valuable cognitive resources on basic comprehension and orientation rather than on the actual purchase decision. This principle is particularly effective for time-sensitive decisions or when customers are already under stress, though it may be less critical for high-involvement purchases, where customers naturally invest more time and attention. The following guidelines demonstrate how to implement this principle in practice.

Guidelines

Minimize steps

Every step is an opportunity for abandonment. The shortest path to the goal is the best. Combine what can be combined. Only ask what is truly necessary. The following examples illustrate this guideline:

• E-Commerce: Amazon's 1-Click ordering: All necessary information is already stored. One click instead of five pages – dramatically higher conversion.
• SaaS-Anmeldung: 'Sign up with Google' – one click instead of an 8-field form. Reducing it to a single step multiplies sign-ups.

Intelligent defaults for the most common cases

Set pre-selections for the most common scenarios: default the delivery address to match the billing address, pre-select the most frequently chosen shipping method, and preset typical quantities. Most users accept the defaults—not because they've carefully considered them, but because changing them requires effort. Use this behavioral tendency strategically to improve user experience and increase conversion rates.

Writing in plain language

# Improved Text Write for a teenager: use short sentences and simple words. Use real numbers, not vague phrases. Put the most important points first—details come later. Avoid technical terms unless you can explain them in one simple sentence. The following examples illustrate this guideline:

• Hemingway App: Highlighting of complex sentences and passive constructions. The app makes visible what reduces fluency.
• Plain English Campaign: Crystal Mark for clear documents. Companies like Barclays and BT use the seal as a trust signal.