The Science of Persuasion in Web Design

Whether negotiating million pound business deals or convincing a toddler that playing with the sharp knife is a bad idea, we have all tried to convince someone else that our opinion is worth considering.  Persuasion is an innate human skill that we regularly use, sometimes without even knowing. Captology (Computers As Persuasive Technologies) is a new discipline that has increased in prominence as we continue to replace human roles with computers.  In a busy market place perhaps captology can give you the edge you need?

Computers and the web have invaded every aspect of modern life.  For example the high street shop assistant has been replaced with the e-commerce website.  Every website has an aim.  Some websites sell stuff whilst others provide information.   As the web becomes more competitive companies are increasingly looking for ways to make their websites more efficient, for example higher conversion rates.

Can we design websites that alter behaviour and “persuade” visitors that they really should listen to our point of view, buy our product or sign up to our newsletter?  What are the moral consequences of following such an approach?

“Persuade me, don’t force me”

The term Computers As Persuasive Technologies (Captology) was proposed by B.J Fogg at the Stanford University.  In captology, persuasion is defined as “the attempt to change attitudes or behaviours or both”.

The application of persuasive techniques to web design should not be confused with coercion which implies the use of force or deception (for example, those annoying banner ads that report false emergencies such as “Your system resources are low. Click here!”).

Persuasive web design should also not irritate users.  Remember the Microsoft Word Paperclip Helper?  How successful was he at helping you write a letter?  There’s a reason Microsoft withdrew the paperclip character from later versions of office.

When designing persuasive websites we are looking for a voluntary and planned change in an attitude or behaviour.  There are multiple ways to achieve voluntary behavioural change online.  This article introduces three common approaches.

“Simplify and Guide Me”

Websites are perfect persuasive tools because they are very good at using large amounts of data and performing complex calculations!  Any website that makes a complex task easy is naturally more persuasive.  If the website is more persuasive then it will be more successful at achieving its goals (whether that is selling T-Shirts or incentivising young people to vote)

For example, imagine a website designed to help people calculate their tax returns online.  This complex activity can be made easier by allowing the website to do all the hard maths!  The website could be tailored so users only have to enter a few key pieces of information (for example, total annual income) and a series of well designed guided steps could walk a user through the whole tax calculations process (no doubt with useful help text along the way).  This simplified process where the website does all the hard work will encourage a higher uptake of visitors to the website.

You might say simplifying and guiding users on websites is not an unusual design suggestion?  It sounds like good usability to me!  At its base level good usability is promoting “persuasive web design”.  As well as simplifying, captology contains several principles that persuade through guiding users, for example the power of customisation.

How many of us have purchased something on Amazon when it has suggested “Other people also bought….”?  “Amazon Recommends” guides users to new products that they may not have considered based upon their previous purchases.  It is one of the most basic persuasive tools implemented on the web but it works because it is tailored to the individual!

Another captology principle that can help make a website persuasive is the power of suggestion.  History buffs amongst you may know this principle as Kairos.  In Greek mythology Kairos was the “god of the favourable moment”.  Imagine a process on a website that requires several steps (for example, purchasing a product or registering online).  At appropriate points in this online process, users of the website will be more open to suggestion than others.

For example, having just booked my flights to New York perhaps the website could offer me good rates on car hire?  Just before I click the confirm button for the “standard package” perhaps the website could inform me of the benefits of the “deluxe package”.  Up-selling is a common technique in e-commerce but how many site designs consider the “when” as well as the “how”?  Could your website apply the principle of Kairos better?

“Let me explore, rehearse and learn”

Sometimes a website will want to educate a visitor about a complex issue.  Imagine a charity website that is designed to raise money to protect an area of rainforest.  No matter how simple the website or how much information or pictures are on the site some users will not grasp the relationship between their money and the impact their donation will have.

The best way of learning something is to do it yourself.  This is where the persuasive power of websites can be put to good effect.  Websites are very good at allowing people to simulate and rehearse actions.

In our rainforest example, the website could have a tool where a user could type in a monitory value and it would tell them how many trees, animals or acres would be saved.  Research suggests that allowing people to practice behaviours and experience their outcomes without risk can increase the chances that a desirable behaviour will be adopted.  This behaviour could be to donate to a charity, vote on a particular issue or stick to an online weight loss programme.

Several years ago the BBC News website ran an interactive tool that enabled users to experience the problems of meeting the UK’s energy supply needs (

The tool allowed a user to decide how much of the UK’s energy would be supplied by fossil fuels, nuclear, renewables and imports by 2020.  Once a visitor had decided how much energy would be supplied by each resource they clicked a calculate button and the website simulated the impact on the UK’s energy needs.  At the end of the calculation users were told whether they had been successful in meeting energy demand and how much an average households energy bills were going to be.

The purpose of the tool was to educate users of the difficulty facing the UK energy sector. As a persuasive medium it is successful because:

  • It allowed users to explore and rehearse several paths to the problem.  Every time they failed they began to understand just how hard it would be to meet the UK’s energy demand;
  • The output of the interactive tool spoke to users in a language they could understand, the impact on their household bills!

“Form a relationship with me”

How many times have you heard someone say “I am going to kill my computer”?  Research has found that we often associate human characteristics to computers.  These social responses to computers are often automatic. As a result, people often treat an interaction with a computer as a social experience!  Websites can be made to take advantage of this!

Websites can be made more persuasive by including virtual social actors.  One of the most famous of these is “Ask Jeeves” (  The virtual butler Jeeves was intended to give an air of “worldly knowledge” to the website.  It was a deliberate design decision to make the character an older English gentleman who people would trust.

The success of virtual social actors is tied closely to the concept of trust.  The character Jeeves works because we naturally associate knowledge with age and experience (a useful trait when the goal of is to answer questions!). Therefore we inherently trust the “older gentleman character” that Jeeves portrays.  The concept of trust in a website is critical to the persuasive power of your website.  If your website is not trusted then your efforts at persuasive design will be in vain.

The virtual character Jeeves was eventually dropped from the website (when it changed its name from to just  But the character proved so successful that reintroduced it in 2009.

Another website that has successfully used virtual social actors is Ikea.  Their virtual sales assistant even went so far as to have tailored hair colours depending on the global market that Ikea was targeting!

The ability of websites to socially support various online activities can be wide.  Virtual social actors can be particularly effective on younger age groups.  However, be careful.  There is a fine line between a persuasion and irritation.  Always remember the Microsoft Word Paperclip!

“Don’t manipulate me”

In conclusion, there are multiple ways in which persuasive techniques can be used in web design.  I have only scratched the surface of the ways in which the design of your website could be used to increase (or decrease) the likelihood of a desirable behaviour.  Writing persuasive copy is an entire article on its own!  A final word of warning.  To quote B.J. Fogg:

Is persuasion unethical? That depends.  Can it be unethical? Clearly the answer is yes”.

Imagine a website set up by an online advertising agency that lets children play with a range of virtual characters.  To progress through games the children must answer questions like “What is your favourite TV show?”, “What is your favourite food?”.

Are you happy with this use of persuasion?  Always ask yourself why you want to persuade your website visitors and is it ethically right?  I will continue this idea in later articles.

Add a comment

Fields marked with an asterisk (*) are mandatory.