Your website needs to convert. That’s the whole point of it, right? You might use yours to capture sales or leads or simply move prospects further into your sales funnel. In all cases, the underlying goal is the same: to change behaviour (in your favour). In this article, we’ll explore seven website-essential psychological biases you should use so your prospects slide through their decision-making process and become customers sooner.
What is a psychological bias?
Technically speaking, a psychological bias (or heuristic/cognitive bias, as they’re called occasionally) is a systematic pattern from rationality or logical decision-making caused by the way we process information. A more accessible explanation would be to consider them mental rules of thumb. They help us make judgements (and thus decisions) without having to experience the pain of long, hard thinking. There are several reasons for this – all originate from our evolution.
For example, deep thinking requires a lot of effort. It’s intense. And because we don’t know what the future holds, we want to preserve as much energy as we can.
These heuristics are also a lot faster. To survive, we’ve had to prioritise speed over accuracy (where ‘good enough’ is sufficient). Think, if a big scary monster confronts us, accuracy assesses trees, caves, or bushes to hide in. Speed tells us to get the f*** out of there.
And because our wiring hasn’t changed over thousands of years, these mental shortcuts still exist and present themselves in our decision-making today.
Why your website needs them
Imagine your sales process as a swimming pool of cold custard. Your prospect visits your website, and they jump in. You want them to get to the other side so they can hand over their money for your product or solution. You’re shouting benefits at them. Discounts. Upsells. But the reality is your prospects quit way before they get to the end.
A website that works avoids resistance. And to avoid resistance, you must work with the way your prospect thinks.
Every website visitor is using heuristics to judge you and what you offer. They are our default setting. So, if you don’t optimise for heuristics, you’re inevitably adding custard powder to the process. You must avoid this and make your website as friction-free as possible.
What’s particularly potent, however, is that by using these psychological biases, not only are you streamlining the process, you’re persuading without detection. You simply present information and your prospects sell themselves, feeling confident in their decision. This is how you create a website that sells. Now, let’s see how you can.
Bias 1: Social Proof
Let’s start with a more obvious and commonplace psychological bias: social proof.
What is it?: Thinking is risky. Making decisions, even riskier. So, why rely on yourself to make the right decision when you can rely on others? Social proof is where we look to others to determine what’s credible and safe. In other words, “AM I GOING TO DIE?” or “NEARLY DIE?” if I buy this product? If others are already buying it, probably not.
Your website visitors are either consciously or unconsciously seeking reassurance that your solution works before they commit and buy it themselves. You must provide it.
How to apply it: Show your popularity and highlight your usage stats. For example, you can showcase testimonials, case studies and brand logos. You could also show how many people already use your solution. You can even share user-generated content to show it too.
To go the extra mile, make sure your website uses both implicit (i.e. something that gives the impression of your popularity) and explicit (i.e. something that states your popularity) means of social proof.
Bias 2: Scarcity
Next, the Scarcity Effect. If you’ve been in the marketing world for less than 14 seconds, you’ll have heard of this. I’ll pretend you haven’t:
What is it?: In ways, scarcity aligns with social proof. So, because we trust others’ judgements and use them ourselves, when there isn’t much of something, we assume it has been/will be popular (and thus trustworthy). The Scarcity Effect means we place a higher value on things with limited availability. It also instils a sense of urgency – so we get them while they are available.
How to apply it: Limit your stock. Or show stock availability (which can imply low stock). If you want to go further and really press those urgency buttons, explain why your stock is low. Research shows that any “because” statement makes the reader more compliant.
Bias 3: Cognitive Fluency
Human behaviour is full of paradoxes. This bias is important but often misunderstood.
What is it?: People prefer messages that are easy to understand and process. That seems common sense, right? But, unfortunately, sometimes the opposite is true (sorry!). So, think of it this way:
When you need to garner attention, you must break patterns and go against the grain (i.e. messages that require some thought). Once you have the attention, revert to simplicity and easy processing.
How to apply it: For your website copywriting, cognitive fluency resides in the words you use and the way you present them. KISS. Keep it simple, stupid. Use conversational, everyday language and present your copy in ways that are easy to read (e.g. well-spaced, legible fonts and high-contrast colours).
Bias 4: The Expectation Effect
A well-written website influences readers in ways not immediately obvious (and far past their interaction with your website!).
What is it?: This bias shows that what you expect largely shapes what you experience. So, if you’re expecting the best product ever, you’ll look for details that reinforce this view. (It’s similar to The Commitment Bias, but more on this soon.) When used properly, this bias can almost nullify your ‘not-so-good’ qualities and exaggerate the better ones.
How to apply it: Above all, this bias reiterates the importance of actually selling your product or solution. I know it can be hard to toot your own trumpet (so… err… hire a copywriter to do it for you), but you need to because underselling hurts you twice: you get fewer sales on the front end, and your customers have a lesser experience, meaning they won’t sell it to others.
This cognitive bias also applies to the little details on your website, your branding and, ultimately, your reader’s experience of engaging with you. Something that feels great often is.
Bias 5: Loss Aversion
You might have heard this one before. You certainly wouldn’t like to forget it.
What is it?: People fear losing something more than they value gaining something of equal value. This stems, again, from an evolutionary perspective where losses have resulted in catastrophic scenarios (e.g. shelter, food, and social status). So we’ve grown protective of what we have – and think we have. Behavioural economics research has shown that the pain of losing something is roughly double the pleasure of gaining something of equal value (i.e. winning £20 feels great, but losing £20 feels very nasty).
How to apply it: Loss aversion goes hand in hand with other psychological biases, in particular scarcity. For example, you can use it with limited-time offers or opportunities. Your reader has the opportunity to get money off or more value than at another time, but the counter is ticking, so they must act now.
Equally, your website copy can frame your offer around what your reader stands to lose (rather than just what they gain). So, you can future-pace and speak as though they already have the benefits of your product or solution. Then take those benefits away and remind them of life without it. You could also emphasise what it costs to not use you.
Bias 6: The Commitment Bias
I love this one. And I’ll probably continue.
What is it?: Once people commit to something, they are more likely to follow through and act in accordance with it (than not). We’re hardwired to chase this sense of “internal harmony” and avoid cognitive dissonance (the uncomfortable feeling of behaving inconsistently with our past actions or beliefs). So we continue to act a certain way once we’ve committed to it. Of course, there’s a limit but you get gist: its predisposition.
You might question what actually signifies a commitment – and that’s a great question. Let’s look at that now.
How to apply it: It’s easier and more effective to lead with a minuscule commitment and then nurture it into something bigger. A small commitment goes undetected (and thus faces less resistance) but still influences the path to your product. So, you can include call-to-value buttons instead of call-to-action. By clicking, they make a mental pledge to what benefit/value/transformation they want.
This is also why breaking your sales funnel down into small steps is worth it – it turns one big leap of faith into smaller, resistance-less steps. Additionally, it creates the opportunity to remind them of past actions and nudge them further.
Bias 7: The Decoy Effect
Decisions are painful. The Decoy Effect makes them perceivably easier.
What is it?: Decisions in isolation are difficult. We don’t like them. So, to make it easier, we can add a third (decoy) option to offer a comparison and identify what option brings the best value.
As The Decision Lab shares, “The decoy effect describes how, when we are choosing between two alternatives, the addition of a third, less attractive option (the decoy) can influence our perception of the original two choices.”
How to apply it: Well, first, if you don’t have three pricing options and you could, try that. Deciding between two similar options is very difficult, often resulting in a “no”. By adding a third, however, we create a perceivably “safer” option.
You can take this further. Be strategic. Let me show you an example from The Economist, which Dan Ariely tested with his students at MIT to see what they’d select. He shared the results in his book Predictably Irrational.

So, not only did the decoy make one choice look better value but it actually increased total revenue too. You can make this even more potent by using social proof and highlighting the most popular option.
Use psychology to reduce friction and boost conversions
For a website to convert, it must make decision-making effortless – almost like they’re making no decision at all. You do that by working with the way your readers are wired to think and, in particular, by leveraging psychological biases. Remember, don’t add custard powder to your sales process!
Now, you know seven of the most sneaky – and also how to use them.
If you want help or have questions, please feel free to reach out. Alternatively, if you’d like to learn more, I uncover how past advertising has used different psychological biases (so you can use them yourself) in my newsletter. It’s completely free. And comes every two weeks or so.
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P.S. if you want your website written for you – with these biases (and many more) – learn more about my website copywriting services here.

