En el Recurso Suelo 15

further considerations to demonstrate this is the case.

Having made this distinction we will now go on to examine some of the consequences and réunifications of hindsight bias. Fischhoff (1975) has shown that outcome knowledge exerts a strong influence over which antecedent items of information are perceived as relevemt to describing

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the event. This is an important finding, and one which requires further research, because information considered relevant in this

way may be more easily assimilated. This would have the consequence

of making it more readily available from memory on later occasions, so providing a complimentary explanation to the account given to biased information search and assimilation in section 2.2.2. of this chapter.

Two other consequences follow from the way in which hindsight biases perceptions of relevant information. First, in searching for information to explain why an event turned out as it did only inform­ ation confirming the outcome might be selected. Second, selective processing of relevant information might well serve to fuel the hind­

sight bias. If such information is more available from memory in the future causal explanations as to why it should have come about may be more easily constructed. The more plausible or greater number of causal explanations seem even more inevitable. Ross et al (1977); Carroll (1978), provide empirical support for this conclusion.

Hindsight bias can also be shown to influence the way in which future events are predicted. This can be seen most clearly by consider­ ing the two ways in which foreign policy-makers misuse history,

according to May (1973). Firstly, in dealing with current events policy-makers are over-influenced by the way in which past events have

turned out. Secondly, they oversimplify a current international crisis

and relate it to the first past analogy that comes to mind without seriously considering the appropriateness of the analogy. For example,

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May argués that intervention in Korea in 1950 occurred because "the President and his advisers perceived a North Korean attack on South Korea as analogous to instances of Japanese, Italian and German aggression prior to World War II" (p52). Once an analogy has been made, May further argues, events and facts are seen as conforming to this image. We have already discussed earlier in this chapter sane of the cognitive processes that explain why this should happen. The point to be made here is that hindsight bias has a crucial role to play also.

In seizing upon an inappropriate or ill-considered analogy from the past policy-makers are too well aware of how it turned out. If, in hindsight, the outcome is seen as more inevitable than it actually was in foresight, applying the analogy to current events will make a similar outcome, if the same measures are used, appear more likely than it actually is. Thus measures thought appropriate

to avoid events turning out as they did in the past may be inappropriately applied to the current crisis. Consideration of policy making in inter­ national affairs provides dramatic illustration of the consequences of hindsight bias. However, there is no reason why the same or similar principles should not apply to domestic affairs and events in our own personal lives.

In summary, hindsight bias is a potentially serious inferential error on the part of the intuitive scientist. It may appear at all levels of social judgment, decision-making and prediction and lead to serious miscalculations, misperceptions and biased information

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by further illustrated example, the potential importance and significance of this phenomena, little more will be said about

it here. Chapter 3 provides a detailed review and critical

evaluation of the experimental evidence for it. Further des­ cription of the methodology and findings is left until then. A discussion and explanation of the cognitive processes involved is left to PART III of the thesis. Here it need only be mentioned that the heuristics of thinking of Tversky & Kahneman, information assimilation and retrieval, and attribution biases play a central role in this discussion.

(b) Other Biases in Prediction.

Further potential sources of bias in prediction stem from over- confidence in judgments (Lichtenstein, Fischhoff & Phillips, 1977) ; poor calibration (Lichtenstein & Fischhoff, 1977); value as a determiner of subjective probability (Slovic, 1966) and preference for concrete rather than abstract information when making pre­ dictions (Borgida & Nisbett, 1977).

Overconfidence in predictions is found when a person is not only requested to give some quantitative .estimate but also to indicate the degree of confidence he has in this estimate. Recent research has reported a consistent bias in confidence estimates. People have been found to be overconfident in evaluating how correct their own

Lichtenstein, 1977; Fischhoff & Slovic, 1976). For example, Fischhoff, Slovic & Lichtenstein (1977) asked subjects to estimate the likelihood that certain factual statements were true (for example, that absinthe general knowledge is

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is a precious stone). They found that subjects who felt certain that a statement was true were often quite wrong.

The appropriateness of subjective probabilities is determined by their degree of calibration (Lichtenstein & Fischhoff, 1977; Lichtenstein, Fischhoff & Phillips, 1976) . A well-calibrated judge is one who is correct, for example, on about half of the occasions that he assigns a subjective probability of 0.5 or odds of 1:1.

Similarly, he is well calibrated if he is correct about three-quarters of the time he assigns a subjective probability of 0.75 or odds of 3:1 and so on. Lichtenstein & Fischhoff (1977) report that judges seem to be quite well calibrated when odds are low (i.e. between 1:1 and 3:1) but become less well-calibrated as the odds increase. For example, they find that subjects who gave odds of 1 x 106 :1 or more were correct only 90% of the time. Thus instead of giving such high odds they should have been giving odds of around 9:1. Furthermore, Fischhoff & Slovic (1978) indicate that this over-confidence is difficult to counteract.

Over-confidence of this sort does have distinct psychological advantages — it is one way in which we can organise and feel a

certain amount of control over our environment. That it is often

misplaced may lead to serious error because an outcome or consequence of a decision we think highly likely may form the basis of a decision or policy. That it is less likely and a greater degree of uncertainty exists means that it may too often go wrong.

One of the possible explanations for overconfidence may be that the value of an outcome or event may be important in determining our

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subjective probability of its occurrance. In general, bias in prediction may enter because certain states of affairs are desired. This idea has a long history, for example, McGregor (1938); Cantril

(1938) both report that wishes and attitudes, among other things, are important determiners in the prediction of social events. More recent research has also found similar effects (Pruitt a Hoge, 1965; Slovic, 1963; Sevon, 1975; Milburn, 1978, Crozier, 1979). Milburn,

(1978) for example, shows that in the prediction of future events positive, and hence highly valued, events were seen as more likely over time. Negative events were seen as less likely over time. For the four time periods 1980-1989; 1990-1999; 2000-2009; 2010-2019, subjects had to assess the likelihood of possible social events such as hunger and poverty no longer being a problem in the United States.

In addition to overconfidence and value the intuitive scientist has a preference for concrete rather than abstract information when attempting to make predictions (Nisbett & Ross, 1980). Earlier in this chapter the research which demonstrated that people ignore base-rate information (even when it would provide more predictive power) was discussed. We now turn to consider how and why concrete or vivid information is preferred when making predictions. Nisbett and Ross (1980) argue that vivid information is more likely to be stored and recalled from memory than is more abstract, sta.tistical data. This may be so because such information has greater emotional interest, provides more detailed and specific knowledge and is more easily assimilated because it is perceived as having high causal relevance. Contributing to this is the Idea that actual experience of an event will have greater impact on prediction and judgment than

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will, say, second hand reports. This area has received little empirical enquiry from social psychologists to date, most of the evidence for this is anecdotal and derives from case histories

(Nisbett & Ross, 1980). From what has been discussed earlier in this chapter it is easy to see why people pay more attention to vivid or concrete information. Such information is more readily available from memory, consequently those engaged in the task of prediction will be more influenced by it. This area should receive more attention from social psychologists in the future. The

research will need to demonstrate, firstly, the extent of the preference for this type of information; and secondly, ways in which people can be encouraged to use more abstract data. Ajzen

(1977), as previously discussed, has provided preliminary research into this. He demonstrated, it will be remembered, that giving base-rate information a causal interpretation results in it being used to a greater extent, and hence aids people to make more accurate predictions.

In summary, this section has indicated a number of serious

shortcomings in the intuitive scientist when he is engaged in the task

of prediction. Particularly important in its own right and from the

point of view of this thesis is the reported bias of hindsight. Outcome knowledge, it was suggested,not only makes events seem more inevitable but provides a partial account for the biased search and assimilation of information discussed earlier in this chapter. Other biases in prediction discussed in this section may also have a direct bearing on hindsight bias. For example, the most available information in hind­ sight might well be that which is vivid rather than abstract. If the

abstract information indicates that another outcome might have occurred then it is even more .likely to be ignored when making retrospective analyses.

In general then, biases in prediction discussed in this section and referred to in other sections impose serious short­ comings on the intuitive scientist to operate effectively and efficiently in a highly complex and uncertain world.

2.3. BIAS AND ERROR

Throughout this chapter the idea of bias and error in the intuitive scientist has been a common theme. Little or no explicit consideration has been given to these terms; it is important to do so in order to establish more clearly what is meant by them and because it is going to become a major research area in the future

(Schneider, Hastorf & Ellsworth, 1979).

Bias, as it has been used in this chapter and in the literature generally, does not refer to individual, idiosyncratic prejudices or

oocur as a result of certain personality traits. It can be character­

ised as referring to systematic error which results from faulty or misused cognitive processes that people employ in social inference, judgment, prediction, etc. Systematic cognitive error of this kind may arise for two reasons: firstly, people may possess the correct programmes but cannot use them efficiently because their information processing capacity is severely restricted (Fischhoff, 1976).

Secondly, people do not possess the correct programmes to guarantee

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that systematic error will not occur. The research reviewed in

this chapter is probably best described as resulting from the

latter shortcoming. However, it is not merely that "people lack the correct programmes" (Fischhoff, 1976. p424), but that programmes have no analogue in any formal or rational model of inference or judgment. This additional qualification is needed because, as has been emphasised throughout the chapter, people are by and large quite successful. If they were just incorrect programmes they would have been abandoned long ago as they would not be adaptive and would lead to continual mis judgment. In the light of this Fj.schhoff's remark could, perhaps, be restated as follows: bias and error result from the same processes that are often successful, the programmes people use have no normative point of reference. Inappropriate use or mis­ use will often produce systematic error.

Bias is often detected because comparisons are made between a normative or rational model and the way in which people actually perform. Ignoring base-rate information, perseverence, hindsight bias, exemplify this. Such a comparison is the source of a potential

problem though: in order to assert that systematic deviations occur

it is necessary for the normative models to be correct themselves. A recent controversy highlights this problem. It will be recalled that use of the representativeness heuristic often leads to bias as base-rate information may be ignored or paid insufficient attention to. Cohen (1979, 1980) argues that the normative model used to predict how people should make such statistical judgment is based on the well- developed Pascalian theory of probability. Essentially, he is

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people appear to perform in accordance with its principles, ot intended to discuss any of the details of this. For the suffice it to say that 'bias' in the intuitive scientist pendent upon which normative model one uses for conparison.

The discussion of bias as systematic error resulting from jpropriate use of non-normative 'programmes' and "systematic, sistent and predictable departure of person perception processes outcomes from processes or outcomes prescribed by a particular adel" (Schneider, Hastorf and Ellsworth, 1979, p.226), will receive iuch greater attention in the future. The above discussion has served to indicate what we mean when we say that the intuitive scientist exhibits bias. But it is not enough, we need to know, in much greater detail, precisely what is meant by such a claim.