How cognitive biases shape email engagement

If you follow my columns here on MarTech, you’ve learned how to make your email content more persuasive and engaging by using devices called cognitive biases, both in your copywriting and in your message design. (See the end of this column for a list of resources.)

Cognitive biases are mental shortcuts people use subconsciously to make sense of information as quickly and easily as possible. We all use them, and most of us probably don’t even know how much we rely on them to help us form opinions and make decisions.

My earlier articles have covered the most popular cognitive biases, such as loss aversion (losing out on a good deal) and social proof (trusting what others have said and done). Researchers have identified 188 individual cognitive biases. Not all of them apply to marketing, but several that you might not be as familiar with can be equally powerful in shaping your subscribers’ engagement with your email.

In this column, I’ll share several cognitive biases that have worked well in my own email marketing and explain how to use them ethically in your campaigns. I’ll also include a B2B email example where I combined multiple biases with an appeal to four types of buyers — a challenging task but one that delivered impressive results.

Why should we appeal to cognitive biases in email copy and design?

People want to process and understand information completely. They simply will not spend minutes puzzling over your email message and what they should do with it. Email readers spent an average of 8.97 seconds reading an email, per a 2022 Litmus study. And that’s only if they open it. 

In email copywriting, shorter sentences and bullet points help the brain grasp important points. Email design techniques like white space around essential information or graphics that point to a call to action draw attention to these key areas and help the reader act. 

Testing can show you which cognitive biases work best for different buyer segments and at different points on the customer lifecycle or journey. The fear of missing out (FOMO), while one of the most commonly used cognitive biases, is often the least effective in many scenarios.

When you learn which cognitive biases are most effective in persuading people to do what you want them to — like opening and clicking on an email message and converting from it — you can use them in your messaging to make your emails easy and even attractive to act on.

Caveat: Use cognitive bias ethically

I’ll say it again: We use cognitive biases not to mislead subscribers or customers or to manipulate them to do something they wouldn’t do otherwise. Rather, these devices can break through the noise in their inboxes, clarify your offers and value and make the decision to click through even easier. Here are three ways you can check yourself to be sure you’re operating above board with your subscribers and customers:

• Align the biases you choose with genuine audience needs. 
• Avoid manipulative tactics, such as fake urgency or misleading subject lines.
• Keep the focus on adding value as you guide and encourage engagement.

Customers can sniff out insincerity and fakery. Don’t do anything that could damage trust in your brand, company, products or services.

4 common cognitive biases that influence email engagement

These are the most commonly used biases in email marketing, especially in one-off email campaigns. They’re easy to use, from writing subject lines to shaping copy and guiding email design for maximum impact.  

1. Curiosity

• What is it? Most people are curious by nature. Ask them a question that taps into an important area and the brain compels the reader to open the email for the answer. 
• Example: “Guess What’s Driving 60% of Our Sales This Month?”
• Ethical use: Be sure your content answers the question in a way that means something to your readers. Nobody wants to feel as if they’ve been taken in by clickbait, which dangles a tantalizing question or statement in the subject line but fails to pay it off in the content.

2. Anchoring effect

• What is it? People rely on the first information you present and use it to judge the value of other information.
• Example: “Normally $299, now only $149!”
• Ethical use: Don’t inflate the original pricing. People who dig into your pricing structure and discover that $149 is your going rate won’t find your offer that impressive and might even feel hoodwinked.

3. Loss aversion

• What is it? People fear losing something more than they want to gain something.
• Example: “Hurry! Only 3 seats left!”
• Ethical use: Balance urgency with authenticity and minimize its use. 

4. Social proof

• What is it? People seek and trust others’ opinions and actions when deciding whether to act.
• Example: “Join 15,000 other marketers using this tool”
• Ethical use: Use genuine testimonials; include full name, company (if B2B), photo and source if possible.

5 cognitive biases to explore for increasing email engagement

Ready to experiment a little? These cognitive biases can add intrigue and engage your subscribers’ brains at a deeper level, especially in special-use emails like abandoned-cart reminders.

1. Von Restorff effect (isolation effect)

• What is it? People are more likely to remember items that stand out.
• Example: “Take 25% off  your first purchase.”
• Ethical use: Highlight a specific word or phrase in boldface or color within your email copy. Use a call-to-action button or highlight a text link in boldface or a contrasting color.

2. Zeigarnik effect

• What is it? People remember unfinished tasks more than completed ones.
• Example: “You’re Almost There — Complete Your Profile to Unlock Exclusive Content!”
• Ethical use: Use this subject line on abandonment emails, whether to complete purchases, applications, account registrations, downloads or any other incomplete action. Tell customers exactly what they need to do.

3. IKEA effect

• What is it? People value the things they create.
• Example: Send an interactive email asking subscribers to vote on the next content piece or product feature.
• Ethical use: Follow up with an email that shows how you accounted for customer opinion in your decisions (e.g., show the vote total for each option).

4. Baader-Meinhof phenomenon (frequency illusion)

• What is it? Once someone notices something, they tend to see it more often.
• Example: Repeat a key benefit or message across multiple emails in a campaign sequence.
• Ethical use: Be sure the content accurately reflects your offer.

5. Endowment effect

• What is it? People value things or benefits they already own more highly.
• Example: “Your VIP Access Awaits — Don’t Miss Out on These Exclusive Benefits.”
• Ethical use: Verify the segment receiving the email qualifies for the benefits you promote.

Optimizing email copy with cognitive bias: A quickstart guide

Now that you have these fundamentals, here are five ways to put them into action beyond the examples I provided above:

• Use curiosity to drive subject line engagement.
• Apply the Zeigarnik effect for ongoing engagement sequences.
• Highlight key offers using the Von Restorff effect.
• Emphasize value with the Endowment effect.
• Test multiple biases strategically within a holistic testing framework. This goes beyond simple A/B testing of individual elements and allows you to compare an email message with one set of biases against another email with a different set.

Quick case study: Boosting engagement with cognitive biases

In a test campaign for my agency, I crafted email content designed to appeal to four buyer modalities— “competitive,” “spontaneous,” “humanistic” and “methodical” — drawing on research by Jeffery and Bryan Eisenberg, the insights of Greek philosopher Hippocrates and the expertise of usability specialist Jakob Nielsen. 

I also incorporated six cognitive biases — authority, social proof, loss aversion, clarity, curiosity and certainty — each of which I’ve found effective through testing with my audience.

View the complete email here. 

Here’s how I structured the email around the buyer modalities:

Competitive (goal-oriented)

• What resonates: “Elevate Your Email Marketing,” “Increased Conversions,” “Comprehensive Audit” and “Key Services.”
• Reason: Direct focus on results, optimization and achieving better ROI.

Spontaneous (in the moment)

• What resonates: The preheader and call-to-action phrases like “Ready to transform your email marketing strategy?” and “Unlock the full potential” focus on quick wins and use results-driven language
• Reason: These shoppers like to decide quickly and often act based on an appeal to emotional needs. 

Humanistic (story- and relationship-driven)

• What resonates: Testimonials and my involvement with client successes
• Reason: Clients need to trust in my expertise.

Methodical (detail- and process-oriented)

• What resonates: Bullet points and a clear breakdown of benefits, explaining the methodology behind my testing plan and email audits.
• Reason: These buyers are logical and detail-focused thinkers who rely on data-driven decisions and specific processes.

And this is how I shaped copy to accommodate the six key cognitive biases:

• Authority: “With over 26 years of expertise” emphasizes my authority and experience, influencing trust in the recommendations.
• Social proof: I included two brief client testimonials addressing competitive and methodical buyers.
• Loss aversion: “Ensuring your emails reach the inbox, not the spam folder” hints at the fear of missing out on potential conversions that result from poor deliverability.
• Clarity: Bullet points and lists clearly outline benefits, helping the reader process information quickly.
• Curiosity (progressive disclosure): The preheader, “Discover how my tailored strategies can transform your campaigns and drive measurable result,” teases results without giving away all the details, encouraging further reading.
• Certainty (data-driven proof): Copy referring to “data-driven decisions” and “increased conversions” highlights measurable outcomes, appealing to methodical or logical thinkers.

Bringing it all together 

As promised, here’s a quick reading list of MarTech articles to give you more background information about writing for the brain by appealing to the mental shortcuts people use to process information quickly and guide their decision-making:

This column, along with the others listed above, highlights the importance of understanding the psychological factors that drive customers to shop — not just in general, but specifically with our brands and companies.

When we understand how people process information and make decisions, we can craft more engaging and persuasive emails. However, it’s our responsibility to use this knowledge wisely and ethically to maintain the trust we’ve worked hard to build.