chap4

CHAPTER FOUR

PERCEPTION OF HAZARDS AND EXTREME EVENTS

In this chapter - Perception, filter and partial views | Influences on perception | Consequences of perception - decision-making | Threshold of perception | Comparative risk assessments

Perception, filter and partial views

Human response to hazards usually fails to match the real probability of being affected by that hazard; our perception of risk normally differs from the reality of risk because we receive, filter and distort information (Figure 5). An individual's understanding is always less than perfect. This creates perceptual uncertainty, which - coupled with environmental variability - means that our views of hazard risk and damage potential are at best partial and selective.

Figure 5. The individual and their cognitive environment. Every individual receives signals and stimuli from the environment around them, and uses these in building up an understanding of that environment and in deciding how best to respond and behave in relation to that environment.

Kates (1971) sees hazards as the outcome of interaction between human use systems (like land-use) and natural event systems (the natural environmental processes which give rise to hazards) (Figure 6). This interaction promotes actual hazard events which we perceive and then respond to. The way we react can in turn modify the human use system (for example by changing land use), the natural events system (for example by changing the magnitude/frequency relationship for river flooding), or both.

Figure 6. Model of human perception and response to natural hazards.

Source: after Kates (1971)

Influences on perception

Perception of hazards is a key ingredient of the model (Figure 6), and a number of studies have explored what factors control this. Socio-economic variables like age, sex, occupation and educational attainment tend to have relatively minor influence overall; experience of past events seems to exert most influence on accuracy of perception, and thus on confidence and ability to predict future events.

Kates (1971) stresses the "prison of experience" and the way in which our past experiences influence our view of risk and hazard threat. His studies of the perception of storm hazards by residents on the east coast of the United States show that past experience does not lead to realistic assessment of future hazard potential, because we underestimate hazard risk. Nine-tenths of the residents he interviewed had experienced storms in the past, but only two-thirds expected them to recur in the future; half of the residents had suffered some property damage from the storms, but only a third expected damage from storms in the future.

Kates's research revealed how people are unwilling to draw logical conclusions from their own experience and they underestimate hazard risk. Saarinen (1966) has shown how perception grows more accurate and discriminating when people have greater direct experience of specific natural hazards. His study of the perceptions of drought hazard amongst farmers in the American Great Plains revealed the most realistic perceptions amongst people with more extreme experiences of drought conditions. Wheat farmers had keener awareness of the possibility of drought than cattle ranchers, because the farmers were tied more closely than the ranchers to the vagaries and extremes of weather. Farmers were also found to suppress their own experiences of past drought, and to over-emphasise hazard-free periods (apparently in an attempt to play down the hazard threat by adopting unrealistically optimistic attitudes). Saarinen also noted the tendency for farmers to favour an opportunist (or gambling) philosophy when faced with the drought hazard; it was there to be beaten, and the good farmer would be the one who managed to survive through it!

The evidence in numerous studies of how residents in hazard-prone sites cope mentally with risk suggests that there are at least five common reactions;

some people deny the existence of the hazard and switch off to the prospect of being threatened in the future
others doubt that the hazard will recur, argue that "lightning never strikes twice in the same place" and put past experience behind them
others attribute responsibility for future events to some higher power or authority (such as God, fate or national government), and adopt a fatalistic attitude of having no control over their own future
another common device is to perceive a regularity in irregular events (for example by speculating that a river will flood every five years and then falsely assuming that there will be five years of peace and safety in between successive events)
some optimists convince themselves that a particular hazard is becoming less frequent over time - even when the evidence reveals otherwise.

Consequences of perception; decision-making

The way we interpret risk and uncertainty from hazards is interesting and important, for individuals and society at large. It shapes how we cope with hazard events when they happen, and influences the ways in which we try to minimise the threat of future damage to people and property. In a broader context, it also influences decision-making about the location and distribution of resource-using activities (like industrial and residential location)(see Chapter 6).

Threshold of perception

The continuum of the hazard event system is mirrored in a continuum of people's perception of hazard events. This perception continuum stretches from complete ignorance, through growing awareness to complete intolerance of a hazardous environment.

Three thresholds can be identified along this spectrum of environmental stress (Figure 7). The first is the threshold of awareness. Up to this point we are simply not aware that we are operating in an environment with hazards - either because the hazard threat is a slow and pervasive one (like the build-up of atmospheric pollution), or because there is no history of previous hazard events at that place (as with long-dormant volcanoes). "Ignorance is bliss" is a typical reaction when faced with limited hazard risk.

Figure 7. Absorption of and adjustment to environmental stress

Once we cross the threshold of awareness, we are conscious of the hazard threat. How we respond, in terms of taking action to minimize risks to people and property, depends on our position relative to two higher thresholds - those of action and intolerance (see Chapter 6). Kates suggests that our threshold of awareness is a product of three main factors. These are the personality, the hazard experience and the perceptive capacity of the individual. Perception will also be influenced by how long we intend to spend in the hazardous area; usually, the longer the stay the more realistic our perceptions.

Comparative risk assessments

Faced with risks and threats from all aspects of life, we tend to cope with uncertainty by favouring certain criteria, which really reflect our perception of risk rather than the reality of it. Sprent (1988) highlights ten common distortions of risk;

we regard concentrated risks (like Bhopal) as worse than diffuse risks (like road accidents), even though the latter may have a much higher annual death toll
we regard risks to non-beneficiaries (such as people living near a nuclear plant, or the crew of a lifeboat) as worse than risks to beneficiaries (such as workers at the power station, or fishermen)
we regard involuntary risks (like poisoning from contaminated food) as worse than voluntary risks (like alcohol or drug dependency)
we regard imposed risks (such as from reducing the staff of the fire service to save money) as less acceptable than risks undertaken for self-protection (such as from the use of a well-tested vaccine)
we regard isolated risks with no compensating benefit (for example, falling through a broken manhole cover in the street) as less acceptable than risks incidental to an otherwise beneficial context (for example, a house being burnt down by a fire in a deep-fry cooker)
we regard immediate hazards (like electrical faults in a new washing machine) as worse than deferred hazards (like faults resulting from poor maintenance)
we regard risks from unfamiliar or unnatural hazards (such as a new food additive) as worse than those from familiar or natural hazards (such as crossing a busy road)
we regard risks resulting from secret activities (like chemical leaks from a defence establishment) as worse than those associated with open activities (like mining or smelting)
we regard risks evaluated by groups suspected of partiality (perhaps based on an industry's own assessment of its safety) as worse than similar risks evaluated by impartial groups (such as the Royal Commission on Environmental Pollution, or a committee of enquiry set up by a learned society)
we regard risks that someone else has to pay to put right as worse than risks for which people have themselves to pay to remedy.

We thus inhabit a world that is prone to hazards, and yet we have at best a partial and selective view of that world and of the risks we face. Perception and reality are different things, and both influence the way we experience and react to hazards.