To create an interactive experience that wins people over, we have to think about emotion and persuasion. The field of psychology deservedly takes much credit for persuasive design. B.J. Fogg’s Persuasive Technology refers to psychology more often than not. Don Norman, with degrees in engineering and psychology, explains the emotional connection with design in The Design of Everyday Things from a psychological perspective. Human Factors International, which as its name indicates stresses psychology and human factors, now offers training on designing for persuasion, emotion, and trust.

Certainly, psychology contributes much. But we need to look at more than psychology for good persuasive design. Here’s why:

• Psychology isn’t the only field that contributes to persuasive design.
  Many fields offer theories and insights that can help us design for persuasion. For instance, rhetoric has been around longer than psychology and offers great ideas, especially for persuasive content. One of my favorite ideas is Aristotle’s emotional appeals–appealing to people through logic (logos), through our credibility (ethos), and through emotion (pathos). Today it’s hard to deny that an approach including all of those appeals usually works.
  
  
• Researchers are usually good at research, not design solutions.
  Psychology focuses heavily on scientific research, which is great. This research helps us understand empirically what works or doesn’t work about a solution and why. But in my experience researchers are best at finding problems, observing experiments, analyzing data, and explaining what happened in an experiment. They often are not skilled at devising design solutions–at envisioning the impact of making certain changes, at coming up with creative ideas, at imagining the possibilities, at integrating several considerations into a holistic design.
  
  
• A design solution should not be based only on general psychological principles.
  I once encountered a cognitive psychologist who tried to convince clients they could “manipulate online behavior” to whatever they wanted using research-based psychological principles alone. Aside from my problems with viewing design as manipulation, I had problems with the way the psychological principles were touted. The principles included positive reinforcement supported by examples such as a video clip of Twiggy, the waterskiing squirrel. (The squirrel learned to waterski by getting treats, or positive reinforcement.) People are more sophisticated than animals or subjects in a Pavlovian experiment. Persuasive designs need to respect that sophistication.
  

  The psychological principle of positive reinforcement helped Twiggy learn to waterski. Persuasive design for people should consider much more than positive reinforcement.

The answer? I think a winning start is to

• Recognize the contribution of other fields such as communication, rhetoric, argumentation, industrial design, graphic design, sociology, and more to the persuasion and emotion factors in design. (I try to bring attention to the value of several of these fields through this blog.)
• Look to those other fields in addition to psychology for help with ideas for persuasive design.
• Look to psychology for help with empirical evaluation of persuasive designs–in other words, conducting the tests and analysis to see whether a persuasive design is getting the results you want and why.