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If you’re like me, you’ve probably experienced that moment where TV episode finishes on a cliffhanger and you just have to know what happens next.

So you watch the next episode, and sure enough it ends on another cliffhanger, and before you know it it’s 4 hours later and you’re still going.

What is it about those shows that make them so addictive? And how good would it be if we could apply those same techniques to our subject line writing so that people just have to open our email campaigns?

In this post, we’ll show you the “open loops technique” that TV producers use to create gripping endings, and show you exactly how you can apply this to your subject lines to help get your email campaigns opened.

What is the open loops technique

The open loop technique is a copywriting trick where you open a story in your copy, but never close it with a satisfactory ending. Kind of like opening a loop but never closing it.

It works because our brains are hard-wired to seek out information we desire. In fact, a study by George Loewenstein of Carnegie-Mellon found that we actually get significant feelings of anxiety when there is a gap between what we know and what we want to know, and we are compelled to seek out the information to reduce those feelings.

It’s this exact theory that explains why we feel so uneasy after being left with a cliffhanger in a TV episode, and why we feel so compelled to watch the next episode to find out what happened.

How to use open loops to increase your email open rates

So how does this help you write better email subject lines and increase your open rates?

By using the open loops technique in your subject lines, you create that gap of information that compels people to open your email to learn more and effectively “close the loop”.

The key to making this work, however, lies in the “what we want to know” part of Loewenstein’s equation.

Think about it for a moment. Chances are you don’t know much about Active Galactic Nuclei, but you probably weren’t compelled to seek out the information either. This is because (up until now) you’d probably never heard of Active Galactic Nuclei, so there was no gap between what you know and what you want to know because you never actually wanted to know about it.

So before you start incorporating this technique into your own subject lines, remember there is masses of information people don’t know, and an open loop will only work in your subject lines if you first show the reader why this information is both relevant and desirable and make them want the information.

Examples of open loops in action

To help you put this into practice, we’ve pulled some campaigns from our inboxes and analysed how these have been made effective using open loops.

Subject: What Bruce Lee can teach you about design

Fast.co Design did a great job of incorporating the open loops technique into this subject line. Being a design-focused publication, their subscribers are interested in learning about design so they use that as the hook to show the reader this is information they want, while using the Bruce Lee reference to show them what they don’t know know and establish the information gap that compels people to open the email.

Subject: This little known copywriting formula can increase your email click-through rate

We used the open loops technique in the subject line of a campaign for our recent blog post on the PAS copywriting formula. Being an email marketing blog, our readers are interested in improving their click-through rates so we used that as the hook to show the reader this is information they want, while using the ‘little known secret’ line to establish what they don’t know and create an information gap that compels people to open the email.

It’s all about balance when using open loops

If you’ve ever seen a story from sites like Upworthy being shared on your Facebook newsfeed, you might recognise this technique at work in their distinctive “This guy started filming his dog. What happens next will shock you” style headlines.

Like all copywriting techniques we’ve talked about on this blog, the key to using them effectively is balance. If you overuse any technique, your audience will start to become immune to it and eventually it will stop having the desired effect on your readers.

Similarly, you may also want to consider the effect this technique will have on your brand. Some people find the extreme “What happened next will shock you” version of this technique quite spammy, and the detriment to your brand may not be worth the increase in open rates.

For us here at Campaign Monitor, our approach is to use them in moderation. We’re ok with incorporating the technique subtly (such as the title of this post and the subsequent email), but you’ll never see us write a subject line like ‘We tried this Hollywood secret in our emails. The results nearly brought me to tears’ as that just isn’t our brand.

In conclusion

Incorporating the open loops technique into your subject lines can increase your open rates by creating a sense of anxiety that compels people to open your email.

However, like any formula or technique it’s all about balance. Use it too frequently and it can lose its effectiveness, and use it to the extreme it can come off as spammy and reflect negatively on your brand.

So pick the frequency and style that works for your organisation and let us know how it goes for you.

Your turn: What are your thoughts on the open loops technique? Have you experienced that cliffhanger moment where you just have to know what happens next? Let us know your thoughts in the comments below!

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This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.
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