4 Cognitive Biases You Need to Know to Make Your Speech More Persuasive

cognitive bias and persuasive speech

When you give a persuasive speech, your goal is not just to provide information to the audience, but to influence their thoughts and actions. While you can strengthen the speech using solid rationale and evidence, you should also know that people don’t always process information logically, and various cognitive biases can lead to illogical assumptions and decisions. Cognitive biases are connected to heuristics, mental shortcuts that help people make decisions using limited information.

Those biases affect human interactions, and public speaking is not an exception. Various cognitive biases that affect the audience’s perception of the speaker and the message in a speech. Being aware of those biases could help us avoid major pitfalls and use psychological insights to tailor our speech content and delivery.

Ambiguity Effect

When people are given options, they are more likely to avoid options with missing information or whose results are unknown. For example, people are less likely to click links shortened by URL shorteners, because the full-length URLs allow people to know which website the link will lead them to, while the shortened URLs do not have such information.

What does this mean for public speaking?

When you deliver a message, especially a message on a complex topic, make sure it’s simple enough for your audience to get it. If you only dump a bunch of data and jargon at your audience, they will feel confused and lost. As a result, that part of the information is missing in their understanding and any call for action based on that information won’t work well because of ambiguity effects. People simply avoid options that they don’t understand.

The key here is to make your audience clearly understand the information and outcome of the action. Complexity won’t impress; it can only make your audience tune out and ignore what you say.

One practical approach is to make references and analogies to relate the new information with something people are familiar with and can relate to. For example, when Steve Jobs gave his speech introducing the original iPod music player, he didn’t merely tell the audience that the new device offered five gigabytes of data, which would sound abstract and complicated to the general audience. Jobs further explained that five gigabytes of data meant you could save up to 5,000 songs in your pocket. By doing so, he related the new information with what the audience was familiar with and comfortable with.

Double-check the logic flow of your messages. As the speaker, you know your topic perfectly well, but the audience may not. Your speech should give them necessary background information and use smooth transitions so that they can follow you easily. If you lose their attention somewhere, you may never get it back. In addition, avoid long and complicated sentences, which usually increase the burden of information processing.

Halo Effects

Our brains tend to make generalized assumptions about a person based on the previous impression of the person. The positive impression of a person in one area can lead to positive opinions of that person in other areas. For example, if you see a person as friendly, you may make an unwarranted conclusion that this person is honest, even though there’s no inherent connection between being friendly and being honest.

What does this mean for public speaking?

The Halo Effect explains why the first impression is so important. When you give a speech, your audience uses the first 30 seconds to form an impression of you. A strong first impression is crucial for grabbing the audience’s attention and establish the speaker’s credibility, and as a result, listeners are more receptive to ideas and recommendations in the speech.

Pay attention to your appearance. Even before you speak, the audience starts to judge you based on the way you dress, walk, and move. Remember to smile and use positive, confident body language. Dress with the right level of formality to fit the speaking setting.

Give a catchy opening to create connections with the audience and gain their trust. Mindful speakers will work hard to develop a strong opening and plan strategically to make a good first impression.

Confirmation Bias

People like to gather and embrace information that confirms their view and ignore and reject information that argues against their views. This is called confirmation bias. We don’t always judge circumstances objectively; instead, we often selectively pick information that makes us feel good.

What does this mean for public speaking?

Confirmation bias suggests your audience will be more comfortable and receptive if the information given in your speech confirms their existing beliefs and preferences. When you prepare a speech, dig deeper to get information about your audience, such as what value they care about and what beliefs they tend to have on certain issues. Such information will help you craft your message accordingly.

If what you are presenting is consistent with their own understanding, it is relatively easier to get their attention and interests. You can even use this bias to your advantage when you give a persuasive message by letting your audience come up with some good examples themselves (which serves as a confirmation of beliefs).

On the other hand, if the information and argument in your speech contradict what they already believe, you have to think more statically to get your message across. In this case, logical persuading is not very effective because people are against listening to the reasoning that doesn’t support their views. According to the article about increasing influence effectiveness on theelementsofpower.com, one technique is to get your audience to “listen objectively to one, seemingly less-threatening part of your argument and get them to shift their position slightly.” After that, you “introduce enough seeds of doubt to eventually get them to see your whole argument, even though it disconfirms their previously held beliefs.”

It is difficult to persuade people to change their ideas because that often indicate that their existing ideas are wrong. One thing you can try is to frame your new ideas as an opportunity to making more progress rather than an admission of the previous errors.

4. Peak-End Rule

Peak-End Rule suggests our memory of an experience, pleasant or unpleasant, does not reflect the average feelings of every moment of the experience; rather, it seizes onto two moments, the most intense point and the end. In general, we have a better recollection of moments that trigger strong emotions–“the intense point.” We are also affected by the recency bias—remembering the end of an effective best.

What does this mean for public speaking?

You need to pay special attention to creating a powerful moment in your speech that works like the climax of a story that evokes an emotional peak, maybe an aha moment or a moment that brings the audience to tears. As the brother Heath claim in Made to Stick, “The goal of making messages ‘emotional’ is to make people care. Feelings inspire people to act.” (p169)

The closing of your speech also deserves deliberate consideration. Give a thought-provoking ending with powerful words that stay in memory. Some great ways to close your speech with a bang may be: a. close with inspiration (such as a compelling message or quote); b. close with a call for action; c. use repetition—craft phrases and structure them in a repetitive format to help create cadence; d. use the title of the speech as closing words (If your speech title is provocative, use it as a compelling closing statement).


Human brains are riddled with cognitive biases that help people understand a situation based on heuristic cues. Logical persuasion is not always effective because of those biases. Understanding the four common cognitive biases and what they mean to public speaking is a crucial step to make your speech more persuasive.