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The ‘heuristics and judgement’ psychology approach within the rationalist paradigm aimed to understand how individuals processed information. It was initiated by Tversky and Kahneman in the 1970s through the heuristics paradigm; the idea that information is processed on the basis of cognitive heuristics, relating to experience based techniques or common sense initiatives which are applied in the process of forming judgements and therefore lead to biases. These heuristics are the primary stage of selecting and processing signals from the world and shape individual judgements of the seriousness of the risk. The three main heuristics include Representativeness, Availability, and the Anchoring and Adjustment heuristics. In the Representativeness heuristic probabilities are evaluated by the degree to which A is representative of B, but prior probability or frequency of an event occurring is not accounted for. Additionally, role of sample size is not appreciated and thus inferences are made from a small number of cases. There may also be insensitivity to predictability which relates to people making decisions based on descriptions of an event. If predictions are based solely on the descriptions provided, then the “predictions are insensitive to the reliability of the evidence and the expected accuracy of the prediction” (Kahneman et al. 1982:8).

Availability heuristics relate to instances where people form a judgement and “assess the probability of an event by the ease of which occurrence can be brought to mind” (Kahneman et al. 1982:11). These events that can be imagined are thus judged to be more likely than events that cannot be easily imagined. Availability is the heuristic most important for understanding risk perception along with the role of the media; “frequent media exposure gives rise to a high level of perceived risk” (Sjoberg, 2000: 2).

There are biases which arise from relying on the Availability heuristic. The first is biases due to retrievability of instances where instances that are more easily retrieved will seem more numerous than those that are less easily retrieved. The retrievability of instances is affected by the salience or quality by which they stand out such as whether events have been experienced or read about. Subsequently another important factor is the timing of occurrences; “recent occurrences are likely to be more available than earlier occurrences” (Kahneman et al. 1982:11). There may also be biases relating to the search set as well as biases of imaginability. If events are thought about and a high number of risks are imagined then the event is seen as high risk, whereas if less risks are imagined, the event is low risk, giving an inaccurate interpretation of the risks of an event. Finally, illusionary correlations in Availability heuristics are seen as the inaccurate judgements of how two events co-occur based on prejudices or selective processing of information. The Anchoring and Adjustment heuristic uses known information as an anchor and adjustments are made as more information is received to create an estimate of the unknown risk. The concern is that the adjustments of the anchor are not enough for the risk to be calculated.

Johnson and Tversky (1983) also explored the role of ‘affect’, which includes emotions, feelings and moods in influencing an individual’s estimate of the frequency of a hazardous event. They found that people tend to make judgements that are compatible with their current mood (affect). There were also two observations of bias in people’s estimates of hazards; individuals overestimated infrequent causes of death and underestimated more frequent causes, and this was related to the availability heuristic and media attention on overestimated risks.

Recent studies have focused on the judgements people make when faced with hazards. The ‘risk as feelings’ hypothesis highlights the role of ‘affect’ experienced when decision making. Finucane et al. (2000a) argued that people have mental representations, which carry an ‘affect tag’. The representations are tagged with negative or positive feelings which will influence the risk/benefit perceptions that individuals have of the hazard. These findings provided the basis for the ‘Affect’ heuristic, where feelings affect risk benefit judgements; “if we like an activity we tend to judge its benefits as high and its risks as low, if we dislike it, we judge it the opposite” (Slovic, 2010:xxi). The “emotional reactions to risky situations

often diverge from cognitive assessments of those risks, and when such divergence occurs, emotional reactions often drive behaviour” (Loewenstein et al. 2001:267).

Thus in the heuristics paradigm people rely on judgemental heuristics to evaluate information instead of assessing probabilities and predicting values. It is recognised that these heuristics can lead to severe errors and inaccurate judgements and became cognitive biases (Tversky & Kahneman, 1974). Nevertheless, the heuristics paradigm is most relevant for this research as the models suggest that affect and emotions may act as cues for probability judgements. This indicates that when “people evaluate the likelihood of occurrence of a risk event, they rely on prior affective experiences, current feelings and images associated with the target event” (Miceli et al. 2008:165). Thus the ‘Affect’ heuristic theory may be most appropriate for understanding how previous experience may influence risk perceptions, and may be more relevant than ‘Cultural Theory’ which is one approach of many within the relativist paradigm.