Four Kinds of Human Factors: 3. Factors Affecting Humans

In the first post in this series, I reflected on the popularisation of the term ‘human factors’ and discussion about the topic. This has brought into focus various differences in the meanings ascribed to ‘human factors’, both within and outside the discipline and profession itself. The first post explored human factors as ‘the human factor’. The second post explored human factors as ‘factors of humans’. This third post explores another kind of human factors: Factors Affecting Humans.

Posts in this series:

  1. The Human Factor
  2. Factors of Humans
  3. Factors Affecting Humans
  4. Socio-Technical System Interaction

17/52 : Tchernobyl – Chernobyl by Eric Constantine CC BY-NC 2.0

What is it?

This kind of ‘human factors’ turns to the factors – external and internal to humans – that affect human performance: equipment, procedures, supervision, training, culture, as well as aspects of human nature, such as our capabilities and limitations. Factors affecting humans tend to include

  • aspects of planned organisational activity (e.g., supervision, training, regulation, handover, communication, scheduling)
  • organisational artefacts (e.g., equipment, procedures, policy)
  • emergent aspects of organisations and groups (e.g., culture, workload, trust, teamwork, relationships)
  • aspects of the designed environment (e.g., airport layout, airspace design, hospital design, signage, lighting)
  • aspects of the natural environment (e.g., weather, terrain, flora, fauna)
  • aspects of transient situations (e.g., emergencies, blockages, delays, congestion, temporary activities)
  • aspect of work and job design (e.g., pacing, timing, sequencing, variety, rostering)
  • aspects of stakeholders (e.g., language, role)
  • aspects of human functions, qualities and states that affect performance (e.g.,
    • cognitive functions such as attention, detection, perception, memory, judgement and reasoning, decision making, motor control, speech;
    • physical functions and qualities such as strength, speed, accuracy, balance and reach;
    • physical, cognitive and emotional states such as stress and fatigue).

The following well-known definition from the UK Health and Safety Executive (1999) seems to emphasise the ‘factors that affect humans’ kind of human factors:

“Human factors refer to environmental, organisational and job factors, and human and individual characteristics, which influence behaviour at work in a way which can affect health and safety” (Health and Safety Executive, Reducing error and influencing behaviour HSG48)

Who uses it?

This kind of human factors is the most traditional in human factors guidance and courses, and so is familiar to human factors specialists. It naturally fits courses on human factors (as modules), texts on human factors (as chapters), and studies on human factors (which might consider specific factors as independent variables).

This kind of human factors is also of interest to safety specialists, who might use taxonomies to classify ‘causal factors’ to incidents and accidents, or select ‘performance shaping factors’ as part of human reliability assessments.

It also suits the way that organisations tend to be organised (functionally, e.g. training, procedures, engineering) and so tends to make natural sense in an organisational context; it is obvious that the various factors affect behaviour. It is just not obvious how.

The Good

Some of the positive aspects of this kind of human factors are shared with the ‘factors of humans‘ kind. One is a great body of knowledge to help understand, classify and predict or imagine these effects. The design of artefacts such as equipment, tools and procedures, as well as tasks, jobs and work systems, affect human performance in different ways. This understanding can therefore be applied to and integrated in the design of equipment, procedures, tools, regulations, roles, jobs, and management systems, etc.

The ‘factors affecting humans’ kind of human factors is also relatively easy to understand at a basic level. Most people seem to know that the design of artefacts (even simple ones, such as door handles, or more complicated ones such as self-assembly furniture instructions) affect our behaviour. The details of the effects are not obvious, but the existence of some effect is fairly obvious.

While the ‘factors of humans’ perspective goes down and in to the cognitive, emotional and physical aspects of human nature, the ‘factors affecting humans’ perspective extends also up and out into the system, environment and context of work. This acknowledges the influence of factors outside of humans on human performance, and therefore helps to explain it. ‘Human error’ is not usually ‘simple carelessness’, but a symptom of various aspects of the work situation. This acknowledges an important reality for any of us; our performance is subject to many factors, and many of these are beyond our direct control.

This kind of human factors therefore more clearly points to design as a primary means to influence performance and wellbeing, as well as instruction, training and supervision. The view of factors affecting humans also mirrors to some degree the way that organisations are designed and operated, as functional specialisms (e.g., training, procedures, design).

Together, ‘factors affecting humans’ and ‘factors of humans’ comprise what many would think of as ‘human factors’, especially staff and managers in organisations.

The Bad

Many of the downsides of the ‘factors of humans’ perspective on human factors are addressed by the ‘factors affecting humans’ perspective. But some other issues remain. One concerns the difficulty in understanding the influence of multiple, interacting factors affecting humans in the real work context. How do factors affect performance when those factors interact dynamically and in concert in the real environment, which is probably far messier than imagined?

In trying to understand performance, we tend to dislike the mess of complexity and instead prefer single-factor explanations. This can be seen in organisations, media, the justiciary, and even in science, which is one facet of human factors. But the effects of multiple interacting factors in messy environments are hard to extrapolate from experiments. Experiments tend to focus on each variable of interest (e.g., a new interface or shift system or a checklist; ‘independent variables’) while controlling, removing or ignoring myriad other factors that are relevant to work-as-done (e.g., readiness for change, culture, supervision, staffing pressures, unusual demand, history of similar interventions, resources available for implementation; ‘confounding variables’), in order to measure things of interest (e.g., time, satisfaction, errors; ‘dependent variables’). Even where we go beyond single factor explanations, the effects of multiple, interacting factors affecting humans in real environments are hard to understand from reading about these factors or from factorial tools such as taxonomic safety databases. They are also hard or impossible to estimate with predictive tools, such as human-reliability assessments or safety risk assessments.

A reductionist, factorial approach can hide system-wide patterns of influence and emergent effects. Factors can appear disconnected, when in reality they are interconnected. Influence appears linear, when it is non-linear. Effects appear resultant, when they are emergent. Wholes are split into parts. Information is analysed but not synthesised. Hence, when a change is introduced, in the full richness of the real environment, surprises are encountered. The air traffic control flight data interface is fine in standard conditions but not for complex re-routings at short notice under high traffic load. The new individual roster system is good for staff availability but adversely affects teamwork. The checklist is completed but before the task steps have actually been completed. Interventions on factors affecting humans are designed and implemented but don’t work as imagined; they are less effective than predicted, have unintended consequences or create new unforeseen influences, changing the context in unexpected ways.

The direction of influence of ‘factors affecting humans’ is often assumed to be one-way (linear), as per the HSE definition above. But people also influence these influencing ‘factors’ in the context of a sociotechnical system. So the design of a shift system influences behaviour, but people also influence shift patterns (e.g., via shift swapping). Interfaces influence people, but people use interfaces outside of design intent. Feedback loops are hard to see with a fragmented and linear approach to human factors. These might sound like rather abstract or theoretical problems, but the examples above are just the first real ones that come to mind; there are many cases of interventions that fail in large part because factors are considered in a non-systemic and decontextualised way that is too far from the messy reality of work.

Additionally, when applied in a safety management context, the ‘factors affecting humans’ perspective is almost entirely negative. From a safety perspective, the positive influence of ‘factors affecting humans’ (and indeed ‘factors of humans’ and ‘the human factor’) is mostly ignored. What is it that makes people and organisations perform effectively to ensure that things go right? Safety management has little idea. Only the contribution of ‘factors’ to unwanted outcomes (real or potential) is usually considered. This can give human factors in safety a negative tone, reducing human activity to ‘causal factors’. Human factors (or ergonomics) is really about something much broader; improving performance and wellbeing, (especially) by design.

There can be something unintuitive and distancing about human factors viewed from a reductionist, factorial point of view. Perhaps it is partly that the narrative of real experience is lost amid the analysis. Consider textbooks, the initial source material for anyone learning human factors (or ergonomics) as a discipline. Relatively few human factors texts are organised around narrative. Instead, they are usually organised around ‘factors’. One of the rare examples of the narrative approach is Set Phasers on Stun by Steven Casey, while an example of the factorial approach is Human Performance: Cognition, Stress and Individual Differences, by Gerald Matthews, Stephen Western and Rob Stammers. Both are excellent in their own ways, but the latter is the default (and happens to be far less interesting to the wider audience). Rich narrative tries to recreate or bring to life lived experience and context, while a factorial or analytical approach deconstructs experience and context into concepts. (Again, an example is incident databases, which analyse factors extracted from multiple situations, partly with the intention of understanding factor prevalence across scale.)

Finally, but related to all of the above, this kind of human factors struggles with questions of responsibility (as with the ‘factors of humans‘ perspective). At what point does performance become unacceptable (e.g., negligent)? How do we locate responsibility and accountability amid the ‘factors’. And if top management is responsible for those ‘factors’, then what when they move on? The ‘human factor‘ perspective, while much misused, at least seems to acknowledge that human beings have some choice and, with that, responsibility. To those affected by situations involving harm (e.g., harmed patients and families, local communities affected by chemical exposure and oil spills), deconstructing the influences on behaviour, in an attempt to explain, may be seen as excusing unacceptable behaviour, sidestepping issues of responsibility and turning a blind eye to the dark sides of organisations, and even human nature.

How to cite:

Shorrock, S. (2017, September 18). Four kinds of ‘human factors’: 3. Factors affecting humans. Humanistic Systems.

Author: stevenshorrock

This blog is written by Dr Steven Shorrock. I am interdisciplinary humanistic, systems and design practitioner interested in human work from multiple perspectives. My main interest is human and system behaviour, mostly in the context of safety-related organisations. I am a Chartered Ergonomist and Human Factors Specialist with the CIEHF and a Chartered Psychologist with the British Psychological Society. I currently work as a human factors and safety specialist in air traffic control in Europe. I am also Adjunct Associate Professor at University of the Sunshine Coast, Centre for Human Factors & Sociotechnical Systems. I blog in a personal capacity. Views expressed here are mine and not those of any affiliated organisation, unless stated otherwise. You can find me on twitter at @stevenshorrock or email contact[at]humanisticsystems[dot]com.

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