Single Effect Copy Theory and Digital Display Ads

Write Label
4 min readNov 29, 2023


By: Scott Zeigler

Write Label’s newest digital offerings provide writers an opportunity to expand their creative portfolio, stretch their talents, and add variety to their writing practice. From shorter projects, like display ad copy, to longer email marketing copy, each digital ad style has unique requirements and challenges.

Today, we’ll look at the email marketing copy components and some tips for writing successful copy.

Single Effect Theory

It all starts with understanding how digital ad copy comes together to form cohesive communication from client to customer. In 1842, Edgar Allan Poe offered the Single Effect Theory to writing fiction. In short, Poe thought that everything in a story should work toward a “single effect.” While this theory is one way of writing a story, the concept is well applied to email marketing copy as well.

Using this concept in email marketing copy will help writers shape copy that has a common theme while highlighting broad aspects of what the business offers to consumers. The single effect of the copy will not be repetitive, but rather it will consistently lean into the key benefits of the business to the email reader.

The keys to the single effect are in the brief. As a copywriter, you’re usually presented with some critical information that can help you find a focus. First, it’s important to look at the target audience, information that typically comes after the copy must-haves. Of course, the must-haves will give you an idea of how the business sees both itself and the consumer. It’s important to browse the company website, if available, to find ways that they present themselves to the public. Company mottos or slogans often provide one way to form a single effect, though your project might be looking to branch out from previous efforts.

For example, the project might be for a garden and landscape business whose key selling point is that they design and build spaces on top of tall buildings. From the brief and the company website, you can see the work they do and start to see what a client might expect. In a best-case scenario, the company might provide a headline, in this case, “Transform Your Rooftop into an Urban Garden Oasis.” And there you have the single effect you can work toward, all in a single word: transform. Everything from here out will lean into that word and concept.

Now the work starts with the first copy, which should capture the reader’s attention, solve a problem or propose a solution that targeted the email to them in the first place and will lead them to the remainder of the copy.

For example, we want to tell a story about their drab rooftop becoming an exciting place for people to gather. We are leading toward our headline, so something like:

Bring your rooftop to life! Create a lush, inviting and colorful space.

This is followed with a headline and subheader, where the reader will be enticed by power words and strong action verbs. These are words that are descriptive and evoke an image. Ideally, the headline and subheader will reinforce the initial copy in a forceful word punch and will narrow the single effect from a couple of sentences down to an easy-to-remember headline and phrase. A strong headline and subheader will have the reader saying, “Yes, tell me more about this!”

The client provided a strong action word, “transform,” and a descriptive phrase, “urban garden oasis.” We’ll use the client-provided headline as a guide: Transform Your Rooftop into an Urban Garden Oasis. To make it fit, the header can be broken into two parts by starting the subheader with the action verb, “experience,” and a descriptive word that reinforces the single effect theme of transformation, “magic.”

Headline: Transform Your Rooftop.

Subhead: Experience the Magic of an Urban Garden Oasis

Which leads the reader to the heart of the email in the second copy. This is an opportunity for the writer to zoom out and show the pieces that make up the whole of the product or service. Whether you choose to write a paragraph or use bullet points, the sentences in this copy continue to surround and illustrate the single effect that has been built into the opening of the copy. These might help to answer some questions the reader had while encountering the initial copy and the headline/subheader combo.

In this case, we’ll use bullet points to show how the rooftop will be transformed, paint a picture of the transformation, and invite them to use the business’s services.

  • Frame the NYC skyline with bright woodwork and greenery.
  • Grow your own vegetables and herbs.
  • Entertain above the frantic city in a fresh, casual setting.
  • Relax and connect with nature in your own tranquil garden.
  • See your vision come to life with [client name’s] expertise.

By the end of the email, at the point that the reader is presented with a call to action (CTA), the single effect copy will leave no doubt to the reader about the business and how their product or service will enhance their life.

With limited space and a short time to capture a reader’s attention in email marketing copy, the Single Effect Theory can help a writer take a seemingly broad brief and narrow it to copy that captivates a prospect.



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