Many factors contribute to the success of a company — outstanding leadership, sound business strategy, an ironclad competitive advantage — but what about social psychology? In his seminal 1984 bestselling book Influence: The Psychology of Persuasion, social psychologist Dr. Robert Cialdini outlined six principles that influence human behavior and persuade people to say “yes.” More than 30 years later, they still hold true.

By understanding the power of influence and how to apply it to marketing campaigns, you can easily impact customers’ decisions and increase conversions. Here’s how to do it, using the six simple yet powerful principles of persuasion.

1. Reciprocity

People tend to return favors. When someone gives us something, we feel compelled to do or provide something in return. Businesses often offer customers free things in the hope that they’ll repay the favor in kind someday, either by purchasing (or re-purchasing) a product, or subscribing to their mailing lists. Depending on your business type, you can try creating value by offering free trials or samples, content (e.g., newsletters, eBooks, white papers, podcasts), resources, or gifts with purchase. Here are some examples:

Bloomingdales offers multiple types of gifts with purchases:

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Spotify offers a free 30-day trial of its premium subscription:

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CrazyEgg offers a free eBook with a subscription:

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HubSpot provides a free tool that analyzes your marketing and provides an overall marketing grade:

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2. Authority

People in positions of power can wield incredible influence over others — we seem to be hard-wired to defer to authority. We’re inclined to trust and say “yes” to their ideas or recommendations because, after all, they’re the credible experts and they probably know best.

By conveying authority through your experience, reputation, and title (e.g., Founder, CEO, President), you can position yourself as a leader or expert in your field. You can also try featuring logos and testimonials from well-known, authoritative customers that use your product, which lends credibility. All of this can increase your effectiveness in persuading and converting customers. Here are some examples:

Lumosity touts itself as an industry leader with many years of experience:

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Songza provides playlists curated by music experts:

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At the Apple store, technical customer service employees are called “Geniuses,” and repairs take place at the “Genius Bar.” You’re probably more inclined to trust and agree with a “Genius” than an ordinary customer-service representative:

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BOLOGNA, ITALY – AUGUST 6: People visiting the Apple Store on August 6, 2012 in Bologna, Italy by pio3

3. Scarcity

We always seem to want what we can’t have — but why? We tend to perceive rare, hard-to-obtain items as more valuable than those that are readily available. We’ve evolved to think: If it’s scarce, then it must be better.

When optimizing for conversions, scarcity is an effective way to invoke a sense of urgency. By telling customers there’s limited time or inventory, you can create demand and impel them to act quickly. Capitalizing on their fear of missing out on the offer is effective because people care much more about losses than gains (a concept known as loss aversion). Here are some examples:

Deal sites like Groupon create urgency with countdown clocks. They drive home the point that these are limited-time offers, and time is scarce:

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Amazon creates urgency by telling you about scarce inventory, when there are only a few items left in stock:

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Fujifilm created urgency by releasing a limited edition version of a camera. By only producing 10,000 units, they ensured that there was a limited supply:

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4. Social Proof

This principle is about our penchant to “follow the crowd.” We naturally rely on people around us for cues on how to behave, think, and feel. If we see a lot of people behaving a certain way, we tend to view the behavior as correct, and we instinctively follow their lead. The unconscious thought is: If everyone else is doing it, then it must be right.

By showing reviews of products and restaurants, companies like Amazon and Yelp use social proof to help customers make purchasing decisions. In fact, a recent consumer study found that 88% of consumers read online customer reviews to determine the quality of a local business.

On Amazon, information like ratings, the number of ratings, reviews, and the “#1 Best Seller” ribbon are all tools of social proof that help inform consumers’ decisions. Even the “Customers Who Bought This Item Also Bought…” feature is a social-proof tool; we tend to trust others with similar tastes and interests, so we’re likely to be interested in what they bought too. “Bestsellers” and “What’s Hot” lists are also effective, as customers who are not sure what to buy may feel more comfortable buying what others have bought.

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When you search for hotels on, they also give you — in addition to ratings and reviews — information on how many other people are looking at the same hotel, and when the latest booking was. These are additional indicators of social proof: you’re more likely to favorably view a hotel if you know it’s highly sought after and was recently booked, rather than a hotel that nobody is viewing or booking.

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5. Commitment and Consistency

People want to appear consistent in their words and actions — it’s human nature to want to keep your word. So if you make a small commitment or promise, you feel compelled to carry through with it, because you want your behavior to be consistent with your prior commitment.

Businesses can use this principle to increase conversions by asking customers to make commitments. This can be small, like asking them to sign up for their mailing list, or large, like encouraging a public commitment. People are less likely to back out and more likely to behave in a way that aligns with their commitment, which can pay off in increased conversions.

For example, the “It’s On Us” campaign asked people to pledge their commitment to help stop sexual assault. By encouraging people to publicly share the pledge on social media and add a profile photo as well, it holds people to their word and pushes them to stick to their personal commitment.

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6. Likeability

In his book, Cialdini writes, “We most prefer to say yes to the requests of people we know and like.” We are more likely to buy something if we like the people selling it, or if we’re familiar with them and can relate to them. The “Avon ladies” have been using this idea for generations to sell beauty products to their friends and family. Similarly, this is why celebrities are often hired as spokespeople; they’re popular, well-known, familiar faces. When we enjoy someone’s personality or presence, we feel better about saying “yes” to them.

Ask yourself: Is your brand personality likeable and well-known? Can your customers relate to you? Some brands embrace the principle of likeability. Spirit Airlines promotes itself as “the most loved airline”:

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And in 2012, fashion brand Scotch & Soda launched a “We Like You Too” campaign, where they animated fans’ names on a digital window display at their flagship store:

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By understanding the psychology of persuasion, you can easily tweak your marketing campaigns and make the most of these six powerful principles of influence. With these tools, you’ll be able transform your power to persuade and drive more conversions.

Top image: Creative concept of the human psychology by Landush

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