Miller's Law

People can hold about 7±2 items in working memory.

"The human brain can remember only about 7 items (plus or minus 2) at any given moment." ¹

Miller's Law originated from a 1956 paper by cognitive psychologist George A. Miller titled "The Magical Number Seven, Plus or Minus Two". In it, he observed that the average person can hold about seven items in working memory at once, with slight variation. Though his paper focused on cognitive limits in perception and recall, the insight has become foundational for user-centered design. When digital products present too many choices, steps, or features at once, users experience overload. Designing with this limit in mind leads to simpler interfaces, clearer decisions, and more intuitive experiences.

Impact on Products and Customer Experience

Poor design decisions that ignore Miller's Law can lead to cognitive overload, which harms usability and conversion.

1. Interface Complexity:
   • Overloaded menus or navigation bars
     • Users can't find what they need and abandon the page.
   • Long forms or data-dense dashboards
     • Frustration increases as users try to scan and retain context.
2. Onboarding and Workflow Design:
   • Too many steps at once
     • Users fail to complete signups or tasks.
   • Lack of progressive disclosure
     • Everything shown at once overwhelms rather than guides.
3. Ecommerce and Product Selection:
   • Feature bloat or crowded comparison tools
     • Leads to analysis paralysis.
   • Complex pricing tables
     • Users struggle to understand value, eroding trust.

Scenario

A SaaS company adds several new options to its settings panel in response to customer requests. Rather than grouping them logically or revealing them as needed, they display all options in one scrolling view. New users freeze. Customer support tickets increase.

Observed Outcomes:

• User satisfaction scores drop.
• Fewer users complete configuration.
• Support teams report "can't find setting" as a common issue.

This kind of interface clutter stems directly from ignoring memory limits.

Ways to Mitigate the Effects:

Product teams can apply Miller's Law to create cleaner, more usable experiences.

1. Interface Design:
   • Use chunking and grouping to reduce visible choices.
   • Limit visible items to ~5-7 whenever possible.
2. Navigation and Information Architecture:
   • Use progressive disclosure to reveal complexity step-by-step.
   • Prioritize what matters most per screen or decision point.
3. User Testing:
   • Observe when users pause, scroll excessively, or guess.
   • Measure task completion rates and cognitive load via surveys.

Conclusion:

Miller's Law is not just a theory about memory, it's a practical guide for building products users can understand and enjoy. Honoring cognitive limits makes digital tools easier to navigate, quicker to learn, and more likely to satisfy.

• Show only what users need right now.
• Organize information logically and in chunks.
• Remove unnecessary choices or relegate them to advanced settings.

Key Takeaways

• People can only hold 5-9 items in working memory at once.
• Product clutter leads to confusion and disengagement.
• Design should support chunking, prioritization, and progressive disclosure.
• Simpler interfaces improve conversion, trust, and usability.

Summary

Miller's Law offers a powerful lens for simplifying product design. When teams limit the number of visible options and reduce decision fatigue, they create smoother experiences that respect how people actually think. Great products are not just functional, they're cognitively friendly.