Part E - Interaction


Introduce computers as a persuasive device
Describe the marketing techniques used to persuade users

"Man will become better when you show him what he is like" Chekov

Individual | Social | Ethics | Science | Credibility | Exercises

Captology is the study of how computers can be used to persuade people to alter their behavior or opinions.  The term captology derives from "Computers as Persuasive Technologies".  Captology draws heavily on the research results on persuasion in the fields of psychology and marketing.

Persuasive technologies are technologies that intend to change the attitudes or behaviors of persons through persuasion and social influence, but not coercion.  Billboards are a persuasive technology.  They are one of the oldest forms of advertising.  On the other hand, automobile technology is not persuasive.  The introduction of the automobile caused the development of suburbs, but that was never the intention of introducing autombiles.  Whether software is a persuasive technology - alters people's behavior or opinions - does not depend upon the software itself, but on the intent of those who have make its use possible.  In other words, software reflects the intent of those who contribute to its use. 

In this chapter, we describe the use of computers to persuade users, list the different techniques used in individual and social persuasion, present the different ethical theories, and describe the scientific theories of persuasion.

Individual Persuasion

Types of Intent

There are three types of intent:

  • Endogenous Intent
    • comes from the developers who produce the technology
  • Exogenous Intent
    • comes from the publishers who give the technology to others to distribute
    • large companies distribute persuasive technologies
  • Autogenous Intent
    • comes from the users themselves
    • a user has decided to use software to modify her/his own behavior

Functional Roles

Computers that are used for persuasion can serve in several different roles:

  • tools
  • media
  • social actors


As a tool, the computer can provide the user with new capabilities.  With the computer, the user can do things they could not do otherwise.

Computers as tools can

  • reduce barriers to certain behaviors so that those behaviors are promoted
  • make certain behaviors seem achievable
  • provide information for informed decisions
  • shape a person's mental model

For example, a heart rate monitor can:

  • be preset to notify the user when the heart rate goes too high or too low
  • modify user behavior by providing feedback not available without the device


Computers as media can

  • educate users
  • shape a person's mental model

For example, the computerized exhibit at the San Francisco Exploratorium:

  • allows people to make various choices about their sexual behavior
  • shows them the consequences of their behavior
  • seeks to influence behavior by demonstrating the dangers of various behaviors

Social Actors

As a social actor, a computer can serve as a compass to influence behavior. 

Computers as social actors can

  • educate users
  • provide tutorial assistance
  • provide a foil against which the user measures her/himself
  • shape a person's mental model

For example:

  • a children's game has a central character who encourages the children to eat their fruits and vegetables

Social Persuasion

Persuasive technology need not just affect single individuals.  It can produce social effects: 

  • family entertainment software can persuade families
  • software in the workplace can persuade company employees to behave in a way that the company wants to encourage
  • a software product can persuade its users to install new versions by sending notices to all users in the hope that many will upgrade


Domains of social persuaion include:

  • Safety
    • safe driving
    • using bike helmets
    • substance abuse
  • Environment
    • recycling
    • conservation
    • bicycle commuting
  • Personal Management
    • time management
    • study habits
    • personal finance
  • Marketing
    • selling products

Computerized Techniques

The techniques involved in persuasion through computer technology include:

  • just-in-time persuasion
  • comparison shopping
  • simulating experience
  • personalization
  • recommendation
  • collaborative filtering
  • monitoring and tracking
  • competititon

Just-In-Time Persuasion

Many users make their decisions at the last minute.  This type of persuasion works best when the suggestions are made on the spot.

For example:

  • decisions at the grocery store on what food to purchase
  • healthier choices through handheld devices that offer nutritional advice

Comparison Shopping

When a new product is introduced, it is difficult to attract customers.

For example:

  • product websites resort to charts comparing their product to their competitors'
  • provide the customer with evidence needed to make an informed decision and purchase the product

Simulating Experience

Another way to persuade the users is to simulate an experience for them.

For example:

  • One study used a computerized baby doll to simulate an infant.  The doll cried and required constant attention from the people caring for it
  • The goal was to demonstrate to teens what having a child is like and to persuade them to act in a sexually responsible manner


Users pay more attention to information when it is personalized.

For example:

  • provides information on pollution
  • It allows the user to enter their zip code and provides information on their area
  • This is far more relevant than information at the national level


Some e-commerce web sites use recommendation as a persuasion technique.

For example:

  • the site asks the user a series of questions about their requirements
  • the site presents the user with a list of products that meet their specific needs

Collaborative Filtering

Collaborative filtering recommends products based, not on their attributes, but on the preferences of people similar to the user.  This has proven to be a successful marketing strategy.

For example:

  • create a profile of the user
  • find other users with similar profiles
  • show the user the products that the other users selected

Monitoring and Tracking

Some software monitors and tracks a user's behaviour and recommends changes.

For example:

  • companies use this to ensure that employees wash hands after using the washroom
  • its use is highly controversial as it is seen as an invasion of privacy


Most people are motivated to win competitions.

For example:

  • some online bidding sites structure bidding as a competition between bidders
  • they inform the bidder of the competing bid and encourage the bidder to win by beating that bid


Persuasion raises ethical concerns.  Ethics refers to the standards that we use to judge the rightness or wrongness of an action, a decision, or an entire way of life.  In this sense, ethics is sometimes called moral philosophy. 

Virtue Ethics

Plato and Aristotle thought that people were inclined to be good and sought happiness.  Wrong came about mostly because people misunderstood how to achieve happiness and not becuase they wanted to behave badly.  In other words, the source of wrongfulness was ignorance, not intent. 

Plato suggested wisdom, courage, justice, and temperance as virtues.  Aristotle added generosity, truthfulness, friendliness, and prudence.  The act is good because of the person, not in and of itelf. 

Normative Ethics

The Golden Rule

The Golden Rule:

  • do onto others as we would have others do onto us
  • do onto others as you would have them do onto you
  • do not do onto others as you would not have them do onto you

The Golden Rule is wholly subjective.  It depends only on what the subject wants or does not want.  It does not tells us

  • anything about animals, children, or the mentally incapacitated
  • if we are asking too much of the other
  • anything about wanting to be treated in particular ways
  • how to handle winning a lottery
  • about the limitations others impose on themselves


Deontological theories approach normative ethics from the viewpoint of duties, obligations, and responsibilities to others.  'deon' stands for duty in Greek.

  • the problem is finding out which duties are the correct ones
  • self-evident things that one does not do
  • do not do onto others as you would not have them do onto you

Immanuel Kant phrased this in terms of the categorical imperative:

  • act as if the maxim of your action were to become through your will a universal law of nature
  • act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end

Deontological theories tend to be foundational in some sense: 

  • based on some assumption
  • trivially obvious propositions have changed throughout the ages


Consequentialist theories identify the morality of an action with its consequences.  The theories divide according to the object of the consequences.  An action is morally sound:  'deon' stands for duty in Greek.

  • Utilitarianism - if the consequences are positive for everyone
    • Act Utilitarianism - approach each act individually
    • Rule Utilitarianism - consider the implications of an action as a rule for society
  • Altruism - if the consequences are positive for others
  • Egoism - if the consequences are positive for the actor

Utilitarianism supports certain ideas for the greater good: 

  • maintaining slavery
  • aggression against another culture
  • maintaining unfair or undesirable systems
  • building a mall at the mouth of the Don River

Evolutionary Ethics

Edmund Wilson (1921-2002) is an American biologist who worked at Harvard University and coined the term 'sociobiology' and proposed an evolutionary basis for ethics.  Evolutionary ethics asserts that our need to behave ethically is the result of biological evolution.  A society where members are just self-interested individuals cannot survive.  Notions such as honesty and cooperation have a biological explanation.  The issue is not so much what is good as it is why do we act in the way we do.

Reflective Equilibria

John B. Rawls (1929-present) was an American philosopher who worked at Harvard University and coined the term 'reflective equilibrium'.  Reflective equilibrium is a state of balance amongst a set of beliefs arrived at through a process of mutual adjustments. 

Rawls work is based on the notion of justice as fiarness:

  • personal fairness - anyone can only be free to the extent that everyone else may also be
  • social fairness - if there are going to be inequalities, we expect something good to result for everyone

Rawls introduce the veil of ignorance.  We investigate a possible action not knowing the others' is based on the notion of justice as fairness.  We then open up to further arguments and comparison to what we already think about justice.  This is a constructivist approach. 

Interaction on the Internet

How should we behave when interacting with others on the Internet? 

  • as we would in person
  • with greater care, since we cannot use body language or emphasis to clarify what we mean
  • any way we choose, thanks to anonymity

What standards should we apply in developing and distributing persuasive software.  Daniel Berdichevsky has proposed the following guidelines:

  • The motivations and intended outcome of persuasion should not be unethical
  • The persuasive techniques should be visible to the users
  • The creators of the persuasive technology should be aware of all predictable outcomes of the use of their technology

Science of Persuasion

Has the time come for us to study persuasion in a scientific way?

  • Have you ever been tricked into saying yes?
  • Have you ever bought something you didn't really want?


The science of persuasion addresses numerous characteristics including the following, which have been studied in human psychology:

  • reciprocity
  • consistency
  • social validation
  • likability
  • authority
  • scarcity

These characteristics evolved in humans as benefits to people who live in groups.  Successful people in sales and marketing

  • know these characteristics
  • use them to best advantage in their daily business


When people are given something, they tend to feel an obligation to repay what they have received.

  • The Disabled American Veterans appealed for contributions and got an 18% response
  • They distributed free address labels with their request and the response doubled to 35%

Offer free samples, free evaluation, or free anything and you will increase the likelihood that the customer will buy from you.


People tend to act in a consistent manner.

  • A charity for the handicapped got potential donors to sign a petition to support the handicapped in the neighbourhood
  • Later they asked for donations and received far more than before they had collected signatures for the petition
  • Once people pledge their support for something they will continue to act that way

Social Validation

If people see a lot of other people doing something, they tend to assume that it is a good idea and tend do it too.

  • One man stops on a street and looks at the sky
  • Other people simply step around him
  • 15 people stop and look at the sky
  • Everyone else on the street looks at the sky to see what is happening

If you can show that

  • a fair number of people have bought your product
  • large numbers will visit your web site
  • many people will recommend your service
  • prospective customers will assume that you must be worth doing business with


People are more easily persuaded by people they like.  People

  • take advice from their friends
  • buy more from attractive sales people
  • vote for politicians who are better looking

Show attractive people selling and using your products.


People tend to respond to authority.

  • If the man who stops to look at the sky is wearing a suit and tie more people will look at the sky
  • If you say, "more doctors recommend...", more people will pay attention

The problem with following any authority is that few bother to discover if that authority is credible.


People tend to want items more if they know there is a scarce supply.

Sales people:

  • call customers to sell beef
  • then call and tell them there is a shortage of Australian beef and this is one of the last shipments
  • sales double instantly

Mark your products "last stock before Xmas" or "with high sales volume, stock will be gone by the end of the week".


Originally, people tended to treat computer information as infallible and believed everything that they saw displayed.  As more on-line information has proved to be incorrect, more users have started to doubt what they observe on computer screens. 

What Affects Credibility:

  • Trustworthiness
    • whether the viewer believes what you say
    • largely depends on whether you have been right in the past
  • Expertise
    • the higher the expertise you can claim in an area the more likely you are to be believed
  • Layout
    • cool color tones
    • balanced layout of the interface

Regaining Credibility

Once credibility has been lost, it is quite difficult to regain.  You can try to regain lost credibility by

  • delivering reliable information over a long period of time
  • delivering the same incorrect information repeatedly alongside reliable information so that users learn to ignore the incorrect parts and gain trust in the rest of your information