18. Human factors


Human factors, as a discipline, derives from the problems of designing equipment operable by humans during World War II (Sanders and McCormick, 1987) and thus originally had strong military ties. The focal point of the discipline was sensory-motor aspects of man-machine interaction (for example the design of flight controls and other military hardware). The interaction between man and machine were originally not viewed in terms of communicative and cognitive aspects but viewed at the very tangible, muscle-operated level. This was, among other things, what became a problem for the discipline as new advances in monitor/screen technologies changed the interaction style. In the early 80s, the discipline of HCI spawned from the Human Factors community (as well as from other disciplines such as Cognitive Psychology/Science) and focused on the cognitive or epistemological coupling between user and system.

The (sometimes problematic) assumptions of Human Factors

It is very telling that the word 'factors' in 'human factors' occasionally is equated with 'limitations'. From the Human Factors literature, one gets the impression that the 'factors' of computer systems were regarded at least fairly predictable, whereas the 'human factors' were not and hence attempted 'ruled out'.

An assumption of the Human Factors community was that insight into e.g. cognitive, sensory-motor, and perceptual aspects of human behaviour could instigate the design of an optimum performance of 'man in concert with his machine', viewed as one united functional system/unit. With knowledge of 'generic' human factors or 'basic' human behaviour and cognition, it was thought that an optimal coupling between man and machine could be found. However, as the discipline evolved, the hunt for 'human constants' proved problematic as well as it proved highly difficult to establish the design implications of such constants.

The stance of the Human Factors community toward this kind of 'singular ontology', i.e. that truth or meaning is 'out there' as in a natural science, came under heavy criticism by many, e.g. Suchman (1987) and Winograd and Flores (1987). In consequence, the HCI community, which had spawned from the Human Factors community, took a "contextual turn" toward more humanistic and sociological accounts of meaning from the late 80s and onward. Aspects like context were now given higher priority and meaning and truth was seeked in the interaction between man and machine or as a product of the wider context. For a short review of the contextual turn, see Jensen and Soegaard (2004).

Human factors, or limitations, include:

  • Impatience
  • Limited memory
  • Need analogies
  • Limited concentration
  • Changes in mood
  • The need for motivation
  • Prejudices
  • Fears
  • Make errors
  • Misjudgement
  • Prefer speech
  • Process information non-linearly
  • Near-sightedness
  • Colour-blindness
  • Distraction
  • Can only perform a limited number of concurrent tasks
  • Short-term memory works differently than long-term memory
  • Users are all different
  • Think in terms of ideas composed of words, numbers, multimedia, and intuitions.
  • Fatigue
  • Must see and hear to understand
  • Physical inability
  • Need information presented in sets of threes
  • Need complex information presented hierarchically
  • Confined to one physical location at a time
  • Require practice to become good at doing things
  • Embarrassment can act as a limitation to accomplishing some tasks
  • Tend to do things the easy way
  • Resistance to change
  • Can be physically harmed by some tasks
  • Prefer to learn by doing than by explanation
  • Have difficulty converting ideas into modes of communication
  • Have difficulty converting modes of communication into ideas
  • Act irrationally
  • Sometimes affected adversely by stimuli such as colour and patterns
  • Become nervous
  • Miss details when tasks are memorized and performed cursorily
  • Can be affected by socio/political climate.
  • Prefer standard ways of doing things
  • Constrained by time
  • Incentive driven
  • Work better in groups than individually (1+1=3)
  • Require tasks to be modularized in order to work in groups
  • Use intuitions to construe information that is sometimes wrong
  • Rely on tools to complete tasks (like spell checking) thus causing dependency
  • Must delegate responsibility in order to free the mind of complexity
  • Become addicted
  • Associate unrelated things
  • Sometimes do not trust what is not understood
  • Death (typically a concern in trains or aeroplanes)

The list is adapted from Michael Osofsky, published source unknown.

Further reading

The best and most authoritative introduction of research in the Human Factors discipline is Sanders and McCormick (1993)

Note: The term 'Human Factors' is sometimes used (in especially North America) as a synonym for HCI or Usability.

18.2 References