The Length-Implies-Strength Heuristic: How to Use Psychology to Your Advantage
How Length Influences Decision-making
Picture this. You’re researching a topic for a project, identifying reliable sources, and compiling as much relevant information as you can. You find two books on the subject matter: one that is 200 pages and one that is 600 pages. Based on that information alone, which source would you say seems more credible?
If you picked the 600-page book, the psychology of heuristics would suggest that you're in the majority.
Most people would assume that the 600-page book is inherently more credible because, after all, with 600 pages, you’d have to know your stuff — right?
This assumption is an example of the Length-Implies-Strength Heuristic, or LISH.
A Heuristics Crash Course
Heuristics, or the process of learning through cues and shortcuts (as opposed to systematic processing), refers to how our brains reason with information without complex critical thinking. Critical thinking is typically taxing, complicated, and more time-consuming than many people can afford.
That said, when we need to determine if information is accurate or valid in a pinch, our brains are hardwired to use heuristic processing. This simplified form of judgment relies on rules of thumb and instincts to form opinions rather than cold, hard facts.
There are many different heuristics in social psychology, but the consensus heuristic is used on a near-daily basis. Often called “bandwagon” or “peer pressure,” the consensus heuristic describes the human tendency to infer “everyone else believes it, so I should believe it too.”
In many cases, heuristic-based inferences are accurate assumptions. Seeing a group of people running away from an area while screaming, for example, would probably make you think twice about approaching it. Even without knowing specific details about what occurred, you still subconsciously recognize the signs of danger: running, screaming, and panicking.
Heuristics in Marketing
Marketers frequently take advantage of persuasive heuristics to influence consumer opinions.
Let’s say that a grocery store sells soda cans for a dollar a piece. This grocery store wants to increase its overall soda can sales. They might use the promotional phrasing “10 for 10” — 10 sodas for 10 dollars.
Since we already knew that the grocery store sells soda cans for a dollar, the price of 10 dollars for 10 sodas should not surprise you. However, to a regular patron, 10 sodas for 10 dollars would sound like a great deal.
That’s because statistically, consumers are more likely to make purchases if the products are marketed in a manner that implies a good deal. That’s another example of heuristics at work!
On the other side of the equation, there’s LISH.
Harnessing the Power of LISH
Ever notice how the backs of novels are loaded with testimonials from other credible authors and publications?
David Ogilvy, the Father of Advertising, once said: “The more you tell, the more you sell.”
The length-implies-strength heuristic — LISH — is based on our tendency to assume that longer copy = stronger material. In other words, the more details, testimonials, stories, and words that you use, the more likely you are to impress, gain credibility, and persuade your audience.
But bigger is not always better!
Short copy vs. long copy is one of the most contested debates in marketing. Our take? A little bit of both.
Short-form copy is great for generating impulse clicks, making it perfect for social media. Short copy consists of a provocative “hook” and a call to action.
Long-form copy lends itself to more powerful persuasion. It lets you tell a complete story, giving you the chance to preemptively respond to objections in an engaging way while triggering an emotional response from the reader.
Think: Why should you buy my product? Why should you agree with my opinion? What makes my business better than my competition?
“So, is it true?” You might be asking. “Do more words mean more substance?”
In many cases, yes. Statistically speaking, longer copy converts significantly better than shorter copy, as it gives the writer the chance to captivate the audience.
However, LISH is not always the answer. If your content is repetitive, low-quality, or excessively dry, don’t expect to get a lot of conversions. Consider purpose, goals, and the factors that motivate you to make a purchase.
And before you pick up that 600-page book, flip through the pages. If it seems rambly, drawn out, and not backed by sources, you’re probably better off picking the 200-pager.