Understanding HCI

User classification

There are 3 main types of user

  • Novice
  • Knowledgeable / intermittent user
  • Expert / frequent user

Users can however, be classified in any other way that is appropriate to the system being built.

  1. Some users may have keyboard skills, others not.
  2. Some users may have knowledge of other similar systems, others not.

The advantages of classification mean that generalisations can be made about users and their needs.

  1. This doesn’t necessarily mean that the best system has been designed for every individual.
  2. It means that the system has been designed to fit the generalisations for each user group.

The Novice

  1. For the novice user of a system, progress is slow because of the limitations of working memory.
  2. Chunking is almost entirely absent.
  3. Systems used by novices require more feedback and more opportunities for closure.

Guidelines for novice users

  • All initiatives should come from the computer – the novice may not know what is to be done
  • Each required input should be brief – the shorter it is the more likely it is to be remembered
  • Input procedures should be consistent with user expectations – humans search for patterns and will generalise
  • No special training should be necessary – especially true in the case of web or multimedia where the user is ‘on their own’
  • All system messages should be clear – in the language of the user, not the designer
  • User decision should be made from a small set of options – the more of a selection you offer, the harder it is to choose
  • Users should control the pace of interaction - they need to understand the system and feel that they can control it, and not the reverse
  • User decision making should be a response to a specific request for action – save - y/n?
  • Help should always be available – tutor / book / online
  • There should be sufficient feedback - closure

Knowledgeable / intermittent users

These users need consistent structures, good help facilities, good documentation.

Expert users

  1. These users have fast response time and will require brief feedback.
  2. Experts organise their knowledge according to a higher conceptual structure.
  3. They can recall more than novices because their knowledge is chunked.
  4. Expert users will look for keyboard shortcuts, abbreviated sequences.
  5. Experts can find constant confirmation screens irritating - Use these only when important.

Examples

Logging on according to the experts view and the actual steps

Expert steps for logging on

  1. Input username
  2. Input password

Actual steps for logging on

  1. Press any key to activate screen
  2. Click into input box
  3. Input username
  4. Press tab or click into second input box
  5. Input password
  6. Press return
  7. Wait for welcome message or error message
    1. if welcome message then task ends
    2. if error message then
      1. repeat 2-7 or
      2. toggle 'caps-lock' and repeat 2-7 or
      3. ask for help