The 12 Psychology Principles That Guide Our Test Suggestions
The test ideas you create with AB Split Test aren’t based on guesswork. They’re grounded in principles that explain how people think, decide, and behave online.
We draw from behavioral psychology and usability research to guide what we suggest. Even small changes can lead to big shifts in how people engage with your site.
Here’s a quick look at the core principles we keep in mind when generating test ideas:
1. Hick-Hyman Law
- What it’s about:
The more choices someone has, the longer they take to decide, and the more likely they are to give up. - How it applies in CRO:
Every extra option increases mental load. Simplifying choices helps reduce friction and decision fatigue. - In practice:
Limit form fields. Reduce the number of CTAs on a page. Streamline your navigation to what really matters.
2. Fitts's Law
- What it’s about:
The closer and larger something is, the easier it is to interact with. - How it applies in CRO:
Key actions should be obvious, easy to reach, and not require precise effort to click or tap. - In practice:
Use large, high-contrast buttons. Place CTAs near relevant content. Design with mobile usability in mind.
3. Jakob’s Law
- What it’s about:
People expect your site to work like the ones they already use. - How it applies in CRO:
When your layout breaks common patterns, users get confused and lose momentum. - In practice:
Stick to familiar design conventions like top-left logos, standard nav menus, and top-right shopping carts.
4. Miller’s Law
- What it’s about:
Most people can only hold around seven items in short-term memory. - How it applies in CRO:
Overloading users with too much information can lead to confusion or drop-off. - In practice:
Break up complex content. Use bullet points, short paragraphs, and small visual groupings to help people process faster.
5. Aesthetic-Usability Effect
- What it’s about:
People are more likely to trust and feel comfortable using something that looks good. - How it applies in CRO:
A clean and visually balanced design makes your site feel easier to use, even before users start engaging with it. - In practice:
Improve spacing, font clarity, alignment, and color contrast. These small changes can make a big difference in how your brand is perceived.
6. Von Restorff Effect (Isolation Effect)
- What it’s about:
Items that look different from everything around them are more likely to be remembered. - How it applies in CRO:
When your most important element looks the same as everything else, it gets ignored. - In practice:
Make your primary CTA stand out. Use whitespace, contrasting color, or a different shape to make it pop.
7. Zeigarnik Effect
- What it’s about:
People tend to remember tasks they started but didn’t finish. - How it applies in CRO:
If users begin a process and stop, they’re more likely to return if they’re reminded or nudged. - In practice:
Use progress bars, step indicators, or “almost done” messages to encourage people to finish what they started.
8. Peak-End Rule
- What it’s about:
People judge an experience based on its most intense moment and its ending. - How it applies in CRO:
Improving just one moment and the final step of your flow can improve overall satisfaction and retention. - In practice:
Make your thank-you page, final confirmation, or post-checkout moment surprisingly helpful or delightful.
9. Cognitive Load Theory
- What it’s about:
The more effort it takes to process something, the less likely users are to complete it. - How it applies in CRO:
If your site feels mentally exhausting, users won’t push through. - In practice:
Keep language clear. Reduce the number of steps in a flow. Remove distractions near high-stakes actions like checkout or sign-up.
10. Reciprocity Principle (Cialdini)
- What it’s about:
People feel more inclined to give something in return after receiving something of value. - How it applies in CRO:
Providing helpful content or tools builds trust and increases the chance of conversion later. - In practice:
Offer a free guide, mini tool, or useful tip before asking for a sign-up or purchase. Lead with generosity.
11. Loss Aversion (Prospect Theory)
- What it’s about:
People are more motivated by the fear of losing something than by the chance to gain something. - How it applies in CRO:
Framing your offer in terms of what users might miss helps drive faster decisions. - In practice:
Use phrases like “Offer ending soon,” “Don’t miss out,” or “Your access expires in 24 hours” to encourage action.
12. Social Proof
- What it’s about:
People look to others when they’re unsure what to do. - How it applies in CRO:
Seeing that other people trust or use your product builds confidence. - In practice:
Display testimonials, customer logos, review ratings, or real-time user activity near points of hesitation.
We’ve built these ideas into the way AB Split Test helps you create and run tests.
But understanding why a change might work helps you spot your own opportunities. And when you start thinking this way, you stop guessing and start experimenting with clarity.