This article presents some of the scientific evidence on how to intentionally persuade visitors on a website to take a predetermined action.

'Persuasive technologies apply principles of social psychology in influencing people; principles of credibility, trust, reciprocity, authority and the like'

(Ijsselsteijn, 2006, p. v).

While you may be uncomfortable with the concept of deliberately using persuasion on websites, it is important to keep in mind that philosophers and scholars have been examining persuasion for at least 2,000 years. Today, website design has a solid foundation in Human Computer Interaction (HCI) and is therefore a science. Within HCI is the discipline of Captology and within captology researchers study persuasive technology. For purposes of captology, Fogg (2002) defines persuasion as ‘an attempt to change attitudes or behaviors or both (without using coercion or deception)’ (n.p).

Web sites are the most common form of persuasive technology today. Many are specifically designed to persuade or motivate people to change their attitudes and behavior. The research shows that in as little as 50 milliseconds, a visitor to a website has decided whether remain on a website or not, a decision based mainly on the page’s visual appeal (Lindgaard, Fernandes, Dudek & Brown, 2006). These first impressions go on to determine the visitors judgments on such things as the sites usability, its credibility and purchasing intentions (Web Site Optimization, 2006). In contrast, low-quality and outright misleading websites cause visitors to be sceptical and wary of web-based experiences (Fogg et al., 2001).

Credibility perceptions are based on the websites appearance, where the visitor is able to evaluate multiple dimensions simultaneously (Buller & Burgoon, 1996; Gatignon & Robertson, 1989; Petty & Cacioppo, 1996; Self, 1996; Stiff & Mongeau 2003). These factors include whether the page is appealing, professional, disturbing, the author’s credibility (Fogg & Tseng, 1999), its accessibility and the amount of advertising it has (Lazar, Meiselwitz & Feng, 2007). There is also a direct connection between the credibility of a website’s content and how often that content is used (Fogg, 2003). Based on the overall athletics, up to 75% of a websites credibility has been determined (Fogg et al., 2003), within 3.42 seconds (Bierut, 1999). Thus, first impressions of a web site’s credibility is critical as it will affect its success.

While there are many dimensions contributing to credibility evaluations, researchers have identified two key principles of credibility: trustworthiness and expertise. In other words, a visitor will consider both the trustworthiness and the expertise of a website before arriving at an overall credibility evaluation (Fogg et al., 2001).

For website designers, there is increasing evidence to focus on the enhancement of a website’s persuasiveness (Fogg & Tseng, 1999; Morkes & Nielsen, 1997). Credible website’s improve its persuasive impact via halo effect. What this means is, the more trustworthy and expert the site overall, the more these qualities will ‘rub off’, and so persuasiveness will increase (Colbert, Oliver & Oikonomou, 2014). Yet, website designers still continue to rely more on intuition rather than scientific research (Fogg et al., 2001).

Coercion implies force; while it may change behaviors, it is not the same as persuasion, which implies voluntary change—in behavior, attitude, or both (Fogg, 2002).

An example of Deception would be an Internet banner ad that reports false emergencies (“Your systems resources are low. Click here!”) or that misinform users (“Pornography is downloading to your computer. Click here to stop.”) While such ads might change what people think and do, they do so through deception, not persuasion (Fogg, 2002).

Simply put, Credibility can be defined as believability. Credible people are believable people; credible information is believable information. In fact, some languages use the same word for these two English terms. (Fogg et al., 2001, p.61)

Trustworthiness, a key element in the credibility calculus, is defined by the terms well-intentioned, truthful, unbiased, and so on. The trustworthiness dimension of credibility captures the perceived goodness or morality of the source (Fogg et al., 2001, p. 62).

Expertise, the other dimension of credibility, is defined by terms such as knowledgeable, experienced, competent, and so on. The expertise dimension of credibility captures the perceived knowledge and skill of the source (Fogg et al., 2001, p. 62).

Halo effect - if one virtue is evident, another virtue may be assumed, rightly or wrongly (Fogg, 2002).

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Buller, D. B., & Burgoon, J. K. (1996). Interpersonal deception theory. Communication theory, 6(3), 203-242.

Colbert, M., Oliver, A., & Oikonomou, E. (2014). The Effect of Credibility of Host Site Upon Click Rate through Sponsored Content. In Persuasive Technology (pp. 56-67). Springer International Publishing.

Fogg, B. J., & Tseng, H. (1999, May). The elements of computer credibility. InProceedings of the SIGCHI conference on Human Factors in Computing Systems (pp. 80-87). ACM.

Fogg, B. J. (2002). Persuasive technology: using computers to change what we think and do. Ubiquity, 2002(December), 5.

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Fogg, B. J., Marshall, J., Laraki, O., Osipovich, A., Varma, C., Fang, N., ... & Treinen, M. (2001, March). What makes Web sites credible?: a report on a large quantitative study. In Proceedings of the SIGCHI conference on Human factors in computing systems (pp. 61-68). ACM.

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Gatignon, H., & Robertson, T. S. (1989). Innovative decision processes (pp. pp-316). Wharton School, University of Pennsylvania, Marketing Department.

Ijsselsteijn 2006, ‘Preface’, First International Conference on Persuasive Technology for Human Well-Being, Palo Alto, CA, USA, April 26-27, 2007, viewed 7 May 2014, <>.

Lindgaard, G., Fernandes, G., Dudek, C., & Brown, J. (2006). Attention web designers: You have 50 milliseconds to make a good first impression!. Behaviour & information technology, 25(2), 115-126.

Lazar, J., Meiselwitz, G., & Feng, J. (2007). Understanding web credibility: a synthesis of the research literature (Vol. 1, No. 2). Now Publishers Inc.

Morkes, J., & Nielsen, J. (1997). Concise, scannable, and objective: How to write for the Web. Useit. com.

Petty, R. E., & Cacioppo, J. T. (1996). Attitudes and persuasion: Classic and contemporary approaches. Westview Press.

Self, C. S. (1996). Credibility. An integrated approach to communication theory and research, 1, 421-441.

Stiff, J. B., & Mongeau, P. A. (2003). Persuasive communication. Guilford press.

Web Site Optimization 2006. First Impressions Count in Web Design. Websiteoptimization, <>.