Human Reliability versus Ease of Use

I just read the panel description for a panel from this year’s Human Factors and Ergonomics Society Conference. It was on the relationship between human reliability and usability. There were some interesting perspectives discussed. The panelists all see a mistaken perception among many practitioners that there is a disconnect.

Both groups would prefer a design that maximizes both safety and ease of use, but we all know that we often encounter tradeoffs between them. Usability practitioners want to make things easy as the primary goal. This means making things so simple that they become automatic and require little or no conscious attention.

Reliability practitioners want to interject more consciousness to prevent, or at least reduce, skill-based errors. This is important because skill-based errors are often the most pervasive when we are dealing with experienced workers or domain experts. We get so used to putting our jobs on cruise control that we are susceptible to errors that are more due to a lack of focused attention than to any error in judgment.

This leads to a layered design model that makes sure both objectives are considered. You start out considering them separately but with good communication so that you don’t develop totally different design approaches. And as the design gets closer to completion (i.e. higher fidelity), the two objectives get more fully integrated.

This is very important in domains like nuclear power plant design, air traffic control, and the military. But it is also important in situations like my previous post (e-commerce web sites).

Ease of Use versus Security

I read an article today ($ to read in full) that highlights the importance of context in design. They tested users of an online auction and the tough issue of security. Security is enhanced if you go through a rigorous registration process, but that time and effort often makes the system less attractive. Two key findings of this study are:

1. For users expecting to be using the system for a long time, they preferred the longer, time consuming process that added security.
2. For users that had a higher perception of the security risk, they preferred the longer, time consuming process that added security.

Of course, you are probably thinking to yourself, “duh.” But there are implications that seem to be missing from the design approach of many sites that I use.

1. For sites that expect users to be long-term focused, or can give them that focus during their marketing pitch, they should be willing to create a more security-focused registration process even if it makes the process longer.
2. If a site recognizes that it needs a more security-intensive and therefore longer registration process, they should start by explaining (briefly) to the user why this is important. We take for granted that people know about the risks of identity theft, zombies and worms, phishing, etc. But the number of people who fall victim to these scams suggests that the general public may not have a clue.