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Disgust has been proposed as a possible factor in phobic acquisition and maintenance, particularly in spider phobia. Cognitions and processes concerning disgust were examined in a series of studies with spider phobics, other specific phobics and nonphobic controls. Beliefs about the disgusting nature of their phobic objects were present in phobics but did not contribute to an attentional bias. Measures of global disgust sensitivity were not closely linked to the phobic fear response. The disgust associated with phobic objects appears to have different constituents to the disgust associated with objects that do not evoke the phobic response. In the light of evidence presented here, it seems unlikely that disgust plays a central role in the aetiology or maintenance of spider phobia in particular and specific phobias in general. It is proposed that when stimuli normally associated with disgust become the focus of phobic anxiety the disgust response may be amplified.

The traditional account of specific phobias has concentrated on the fear evoked by phobic objects or situations, rather than other emotional responses. Watts (1986)suggested that disgust was important in phobias, particularly spider phobia. He hypothesised that it was disgust rather than anxiety which disrupted spider phobics' memory for spider information (and which therefore interfered with habituation), as indicated by experiments examining biases in their memory for spider stimuli. In a series of papers, Graham Davey and colleagues proposed that the connection between phobias and disgust may have had adaptive value ( Matchett and Davey, 1991; Davey, 1992a Davey, 1992b Davey, 1992c Davey, 1994; Davey et al., 1993). He postulated that humans are more likely to acquire disgust-based avoidance of stimuli which have been evolutionarily associated with disease or contamination. This is an extension of Seligman (1971)preparedness theory which states that particular classes of stimuli are more likely to be associated with conditioned fear responses due to evolutionary pressures. Seligman particularly cited the conditioned nausea response as one which was persistent and very easily acquired, and suggested that this had evolved in mammals because of the need to protect against poisoning. Support for this was to be found in the work of Garcia and colleagues ( Garcia and Koelling, 1966; Garcia et al., 1977) who had discovered that taste aversions can be conditioned in a single trial, and that once acquired, this conditioning is particularly long-lasting and difficult to undo. This appears to be true only when there is an evolutionary based `belongingness' relationship: in the conditioning of taste aversion this means that the CS has to be novel taste (as opposed to auditory and visual stimuli) and the UCS has to be nausea (as opposed to pain). If disgust is involved it is not clear why this type of process should be relevant to phobias, in which the stimuli are usually visual and auditory, and reported conditioning experiences seldom involve nausea. Furthermore, the person who develops a lifelong aversion to shellfish after an episode of food poisoning does not become phobic of mussels. Rozin and Fallon (1987)were amongst the first to study disgust experimentally and to put it in the context of contamination sensitivity. They describe the disgust reaction as primarily a food-rejection response consisting of nausea, a characteristic facial expression, a distancing of the self from the offensive object, a sensitivity to both contamination from the object and the prospect of eating it, and a characteristic feeling-state (revulsion). They were also interested in the question of contagion, where an object could subjectively acquire the characteristics of another object by being physically close to it ( Rozin et al., 1986) and similarity, where this happens when the object looks similar to another. So perhaps the disgust response in phobias is acquired through association in some way as yet unspecified, and this may in part account for the development of the phobic response. In order to examine the question of disgust/contamination sensitivity, Rozin et al. (1984)devised a scale based on how much those participating in the experiment would like to eat a bowl of soup from a dog bowl, stirred by a fly swatter, containing a dead grasshopper and so on (20 items in all). Additionally, they asked them how much they would like to eat a biscuit after a bite had been taken by an acquaintance, a good friend, a waiter in a restaurant or after it had fallen, unbitten, on the lawn while they were picnicking. They demonstrated an association between the perception of contamination, and avoidance of the object. Evidence for a specific association between the measure of disgust sensitivity and the degree of fear provoked by different classes of animals has come from Matchett and Davey (1991), who found that measures of disgust and contamination sensitivity were correlated with scores on the animal subscale of the Fear Survey Schedule (Wolpe and Lang, 1964). In addition, disgust and contamination sensitivity correlated with fear of animals which were characterised as fear-relevant and not physically harmful (camel, rat, eagle, spider, cockroach, maggot, snake) and also correlated with fear of animals characterised as having high revulsion (maggot, cockroach, slug, rat, snake, spider, snail). This contrasted with the lack of correlation with animals they considered to be physically harmful, attacking or predatory (shark, tiger, lion, bear, snake, jellyfish, wolf). It is not clear why snakes should appear in all categories and rat, cockroach, spider and maggot in two categories. It should also be noted that these results were obtained from nonphobics. Matchett and Davey's suggestion that disgust sensitivity may be a vulnerability factor for the development of phobias is based on these findings. If, as suggested, disgust is implicated in the development of phobias, it is to be expected that phobics who fulfill clinical diagnostic criteria for specific phobia should have significantly higher levels of disgust sensitivity than do fearful, but nonphobic individuals. Mulkens et al. (1996)have shown that spider phobic women are indeed more sensitive to disgust than are non spider phobic women, as measured by the Rozin and Fallon disgust sensitivity questionnaire, and by one of their own behavioural tests (reluctance to eat a biscuit over which a spider had crawled). However, in another behavioural test of disgust sensitivity, which did not involve a spider (drinking tea out of a scale-encrusted cup) there was no difference between the groups. One possible explanation for this and for the other reported differences is that the disgust sensitivity questionnaire, on which the majority of research in this area is based, consists of 24 items, 9 of which are concerned with the amount of disgust generated by insects: a dead grasshopper (6) and a fly swatter (3). Spider phobics may be particularly sensitised to these kinds of items purely because of the nature of the stimuli, i.e. `leggy' insects. Another possible explanation is that — in the test using the biscuit and the spider — the spider phobics were responding to a residual phobic reaction about the spider itself rather than to the biscuit as contaminated by the spider. In support of this, Thorpe and Salkovskis (1995)found that while phobics do have a high of level of endorsement of beliefs about a variety of disgusting qualities which their phobic objects possess, this does not appear to be related to the intensity of their fear. It is possible that, when phobic fear becomes associated with the stimuli which are commonly also associated with disgust, the fear may amplify the `normal' disgust response as part of the general negative evaluation of the phobic object. This would suggest that disgust may not be causally related to phobias. The present paper describes three studies which were designed to explore the links between disgust and phobias. In the first, people fulfilling criteria for simple phobia completed fear and disgust ratings of the type used by Matchett and Davey with the possible confound of categories of animals examined in detail. This study assesses the generalisability of their earlier work with nonphobic respondents, to a phobic population. The second study looks at the way in which spider phobics, other specific phobics and nonphobics react to both spider stimuli and to stimuli which are generally regarded as `disgusting'. This allows a comparison of disgust reactions to phobic stimuli and to disgust-evoking nonphobic stimuli of comparable intensity. The study thus aims to clarify the relative importance of (i) increased sensitivity to disgust-evoking stimuli in phobic individuals and (ii) the disgust response specific to spiders in particular. The final part of the second study explores the possibility that spider phobics have an attentional bias to disgusting stimuli, at both the conscious and preconscious level, which would support the hypothesis, described above, that spider phobics have a greater disgust sensitivity than do nonphobics. The third study seeks to provide a further analysis of the relative contribution of fear and disgust to the phobic response. Spider phobics, other phobics and nonphobics chose the two items which disgusted them most then rated them on a variety of measures of disgust, fear, avoidance and physical characteristics.