Error prevention: how to prevent conscious user mistakes

Preventing errors is the 5th usability heuristic. These errors are not user errors. Rather, they are design errors as the design should be of the sort that does not allow the user to commit errors or at least gives a warning before the user is about to commit an error.

Error prevention can be done by:

• eliminating error-prone conditions.

• presenting users with a warning message (that informs them of the consequences if they proceed) and a confirmation option if they are about to commit an error.

There are two types of errors:

• Slips - unconscious errors that are caused by the inattention of the user.

• Mistakes - conscious errors that are caused by a mismatch between the design and the user’s mental model.

Mistakes occur when the user has formed an incorrect mental model of the interface. In this case, the user has a goal that does not suit the situation well. Preventing mistakes involves forming designs that match the user’s mental models. Assuming that users will eventually learn the interface is an incorrect approach.

Guidelines

The following guidelines can help prevent mistakes:

• Collect user data - it is important to ensure that the user’s mental model matches the designers’ mental model. Gathering user data and understanding users is essential to achieve this. We can collect user data through different methods depending on the context, such as ethnographic studies, contextual inquiry, field studies, etc.

• Design conventions - following the general design conventions helps bridge the user’s Gulf of Evaluation and Execution. Users interact with other interfaces throughout the day, and your interface matching the general design conventions followed by other interfaces eases the experience for the user. For example, the menu icons on an e-commerce website should be placed where it is conventionally placed on other e-commerce websites.

• Affordances - providing affordances to communicate the design to the users. Affordance is how the user interacts with the interface, and the signifier is the visual cue that communicates the affordance to the user, e.g., a shadow with clickable buttons.

• Ask for confirmation - at times, users are not aware of the consequences of their actions. Therefore, it is important to ask them for confirmation, e.g., factory reset will erase all your data, or changing display zoom will restart the phone before performing the action.

Conclusion

Even though these methods cannot completely erase the possibility of mistakes, they can significantly reduce them by matching the user’s mental model with that of the designers as much as possible.