When I begin to teach my undergraduate students about phobias, I always start with a slide showing a large pile of coloured buttons next to a pad of cotton wool. Everybody knows about the most common phobias – things like fear of heights, spiders, water, snakes, creepy crawlies, darkness, death, etc. But sometimes you get what I call ‘common uncommon phobias’ – phobias of everyday objects that people shouldn’t have anxieties about but with a little probing you find that a lot of people do. Cotton wool is one in particular. There seem to be quite a few people who can’t bear to touch cotton wool. If you blindfold someone with a cotton wool aversion and then unexpectedly get them to touch some cotton wool, their hands recoil from it before they’ve even realized what it is. Aversion to buttons is another puzzling phobia. In my life alone, I’ve come across dozens of people who insist on having all the buttons cut off their clothes before they’ll wear them. They are certainly uncomfortable enough with buttons to insist on this strange ritual. One particular example of button phobia reported in the psychological literature is of a 9-year-old Hispanic American boy who was unable to handle buttons. As a consequence he couldn’t dress himself and had difficulties concentrating at school because of an excessive preoccupation with not touching his school uniform or touching anything that his buttoned shirt touched. Outside of school, he avoided wearing clothes with buttons and avoided contact with buttons that others wore (1). Unlike many of the phobias we will talk about later, there did seem to be a event that precipitated this specific fear of buttons. When he was 5-years-old he was pasting buttons onto his posterboard and ran out of them. He was asked by his teacher to come to the front of the class and fetch some more buttons from a bowl on the teacher’s desk. On reaching for the bowl, his hand slipped and he accidentally tipped the whole bowl of buttons over himself – an event which he described as very distressing. I doubt very much whether all button phobias are caused in the same way as this, but this example does highlight some interesting features of phobias. First, after the precipitating event his fear of buttons simply got worse and worse – despite reassurances from his family and friends. This is known as ‘incubation’, in which – for no obvious reason – fear of the object or event simply escalates over time. Secondly, this boy’s phobia significantly interfered with his normal daily living, affecting his ability to look after himself and affecting his educational development. Thirdly, the fear develops into an intrusive and dominating cognitive preoccupation, in which he has to be continually hypervigilant that he does not accidentally come into contact with buttons. Finally, there is an interesting element of fear of contamination in this case history that is common to many phobias. Not only is he fearful of buttons, he is also anxious about other things that may have come into contact with buttons.
|Common Uncommon Phobias|
While we are on the topic of unusual phobias, let me describe another interesting case history so that you can get a flavor of how severe specific phobias are experienced and how this experience develops. Many years ago, eminent clinical psychologist Jack Rachman described in detail a chocolate phobia exhibited by a patient known as Mrs. V (2). She complained of an extreme fear when confronted with chocolate or any object or place associated with chocolate, and even avoided anything that was brown (e.g. she would refuse to sit on any brown furniture). This avoidance extended to avoiding shops that might stock chocolate, and she once walked up eight flights of stairs rather than use the lift because of a brown stain next to the lift buttons. As with our previous button phobia example, her phobia ‘incubated’ over time to the point where she had ceased working because of her fear and was practically housebound. As Rachman points out, fear of chocolate is extremely rare and it is difficult to argue that it has any obvious survival value. Unlike the Hispanic American boy with the button phobia, Mrs. V. was relatively inarticulate about the history of her fear. But according to the accounts she was able to give, her anxieties began shortly after the death of her mother whom she was very close to. Her anxieties first became focused on fear of cemeteries and funeral parlours, and then she became aware of a mild distaste for chocolate some months later. Four years on from her mother’s death and she had become entirely chocolate phobic – avoiding chocolate and even becoming extremely frightened of it. This example illustrates the gradual onset of severe phobias that eventually ‘incubate’ to become distressing and life disrupting. It also emphasizes the lack of insight that the sufferer has into the processes that gave rise to the phobia. Mrs. V. felt sure that she had seen a bar of chocolate in the room containing her mother’s coffin, but in all probability this was a fanciful reconstruction in her attempt to explain her irrational feelings, and in the next section we will discuss the fact that a majority of phobia sufferers (even those suffering mild phobias) are usually at a loss to explain how their phobia started or how it developed.
“IT’S A PAST LIFE THING”
Billie Bob Thornton is a famous actor, screenwriter, director and musician. As accomplished as that sounds, he once told chat-show host Oprah Winfrey that he had a fear of antique furniture – so much so that he simply couldn’t eat anywhere in the vicinity of antiques. Thornton has also admitted that he also has a fear of certain types of silverware, and wrote this fear into his character Hank Godowsky in the film Monster’s Ball, who insists on eating his food with a plastic spoon and fork. What does Thornton have to say about his fears? In an interview with the Independent newspaper, he explained “It’s just that I can’t use real silver. You know, like the big, old, heavy-ass forks and knives, I can’t do that. It’s the same thing as the antique furniture. I just don’t like the old stuff. I’m creeped out by it, and I have no explanation why… I don’t have a phobia about American antiques, it’s mostly French – you know, like the big, old, gold-carved chairs with the velvet cushions. The Louis XIV type. That’s what creeps me out. I can spot the imitation antiques a mile off. They have a different vibe. Not as much dust” (3). How did he acquire this very unusual fear? – well he says that “maybe it’s a past-life thing and I got beat to death with some old chair”! We’ll discuss that possibility later.
Other celebrities have more mundane phobias; film actress Megan Fox is afraid of paper, Country singing star Lyle Lovett is afraid of cows, Cameron Diaz has a fear of door handles, and former Baywatch star Pamela Anderson has a fear of mirrors. You may be thinking, ‘well, these are not as crazy as Billie Bob Thornton’s fears’. But even so, how do people get fears of paper, cows, door handles and mirrors?
By comparison, my own fears seem by my own admission much more adaptive and sensible. As a child I was completely panicked by loud noises – especially pneumatic drills. Whenever we saw a worker in the street using a pneumatic drill my mother insisted on taking me by the arm and dragging me as near as possible to it until I completely freaked out. All I ever remember is struggling frantically so I could just run as far away as possible. Her intention was simply to “get me used to the noise” and my fear would go away. No it didn’t, it just got worse to the point where I become scared of noisy cars, barking dogs, large crowds, and vacuum cleaners. Perhaps more understandable was my fear of dentists. I was about 7 years old when one day I was unexpectedly called out of class and taken across the school yard to a room where there were two people in white coats standing either side of what I thought was just an oversized, leather armchair. Without explanation they asked my to sit in it, lean back and open my mouth. I was only seven years old and no one had told me about dentists! It’s bad enough having someone you don’t know messing around in your mouth for reasons that are beyond you, but then when the loud whirring noise of the drill started up and they began to drill my teeth (without anesthetic in those days) – in the words of Billie Bob Thornton, I completely freaked. I don’t remember whether I felt any pain, but the sheer terror of such an unexpected oral intrusion by complete strangers welding a screaming instrument that looked for all the world like a metallic, writhing snake was enough. My terror appeared to serve its purpose because they were entirely unable to continue, and I was told not to be so childish and stop yelling for my mother (yes, the same mother that dragged me screaming towards pneumatic drills!). Decades later I still only go to the dentists when I’m suffering the most unbearable toothache, I simply cannot watch dentists on TV, and I become anxious when I read a copy of “Punch” magazine – traditionally the dentists’ favourite waiting room periodical.
I’ve described just a few examples of specific phobias that afflict famous people as well as myself. Strangely, as odd as some of these fears are, we seem quite happy to accept that people acquire them and suffer them – perhaps because specific fears and phobias are so prevalent in the population – almost everybody seems to have one. Large scale scientific surveys suggest that a clear majority of the population (over 60%) report having symptoms of a specific fear or phobia at some time in their lives (4), and around 1 in 10 people in their lifetime will report fears of a severity that make them clinically diagnosable and in need of treatment (5). This makes specific fears and phobias the most widely experienced anxiety-based problem, and they cause both distress to the sufferer and disruption to that person’s normal daily living. While we’ve so far discussed a few unusual fears, the vast majority of phobias that are experienced revolve around just a limited number of situations and objects. These include animals – especially bugs, rodents, spiders, snakes, and invertebrates - such as snails and slugs. Then heights, water, enclosed places, social situations, and blood, injury and injections. Most other phobias are much rarer, but no less scary or debilitating for their sufferers. Even so, the origins of these phobias are no less puzzling than those of Billie Bob Thornton and his fellow celebrities.
The commonness of fears and phobias seems at least in part to explain why we appear to accept that people acquire and suffer specific fears and why it seems almost ‘normal’ in a strange way. But this does raise the matter of where specific fears come from and how they are acquired. For example, how can people acquire fears that are so very specific (e.g. antique furniture, door knobs, paper) and represent debilitating fears of things that the vast majority of people would say are absolutely – and without argument – harmless!
Well, why don’t we just ask them how they acquired their fears? What is surprising is that most people will simply not be able to tell you. Their usual response is “well, I always seem to have been frightened of mice”. Some years ago now, we conducted a survey of 120 people who claimed to have a fear of spiders (one of the commonest phobias in western cultures), and we asked them all to try and recall an event that precipitated their fear. Only one person out of 120 was able to do this. She was a secretary who told us that her fear of spiders started on an occasion when she was being sexually harassed by her boss, and at that very moment she remembers seeing a spider scuttle across the floor in front of her. From that moment on she could not go near a spider, watch spiders on TV, or even stay in the same room as one (6). In contrast, no other respondents could recall a specific event as the cause of their phobia - only that they seemed to have had the fear for as long as they could remember, or that it had developed so gradually that no one single event seems to have been responsible. These findings are not unusual. Snake phobics, for example, have hardly ever been bitten by snakes. In a study of 35 highly snake phobic individuals in the USA, only 3 had been bitten by a snake – yet most were still so fearful of snakes that they couldn’t even bear to look at a picture of a snake (7).
It’s the same with water phobia and height phobia. For example, Australians love their beaches and their water sports, so water phobia is a real problem if you’re a red-blooded Australian youngster growing up on the coast. Not surprising, then, that most research on water phobia has been carried out in Australia. However, rather than being able to identify the causes of water phobia and develop interventions to prevent it, these studies merely added to the mystery. Are water phobic kids having bad experiences with water? Are they being thrown into the deep end of swimming pools by their older siblings? Seemingly not, over half the parents of children with water phobia believed their child’s phobic concerns about water had been present from their first contact with water (8). So their fear of water seemed to exist even before their first serious encounter with it.
Just one final example before we move on. I am severely height phobic – which doesn’t help when I have to call in on the ever-growing number of University Psychology Departments with trendy glass atriums, and visit monolithic shopping malls with glass-sided elevators. I even had to leave the Van Gogh museum in Amsterdam in panic when I realized that I’d have to walk up glass-sided stairways to mezzanine floors with glass balustrades to view my favourite Van Gogh paintings. Needless to say, my fear won out and I didn’t view any of the exhibits and now have a strangely ambivalent reaction to any Van Gogh paintings. Height phobia is universal and also very common. But the number of height phobics who have fallen off ladders or cliffs, fallen down steep flights of stairs, or broken their legs falling off mezzanine floors in Van Gogh museums is very small. Around 1 in 5 height phobics can recall some bad experience when their phobia began, but then again – paradoxically – these recalled events are rarely accidents. They are often just recollections of feeling very frightened or panicky while in a high place. Around six out of ten people with height phobia – just like water phobics – claim their fear has always been present (9).
|The Height Phobic's Nightmare - The Van Gogh Museum in Amsterdam|
We’ve now discussed a number of common phobias in which a large majority of sufferers cannot recall a precipitating event or experience. This mystery is puzzling given how frequent specific fears and phobias are in the general population. Billie Bob Thornton’s tongue-in-cheek view of his phobia of antiques is that “it’s a past-life thing and I got beat to death with some old chair”. Alternatively, he might have been abducted by aliens and taken to a room on their spaceship filled with dazzling white light where they implanted the fear of antique furniture in his brain and beamed him back down to earth to ponder his baffling complaint. Well I doubt it!
So, if phobia sufferers are at a loss to explain their condition, and these fears seem to have been around for as long as they can remember – where do they come from? – are they a result of some biological pre-wiring constructed by our evolutionary past?
ESCAPE FROM THE MAN-EATING SLUGS
Let’s begin this section by creating an historical scenario. Conjure up an image of your ancestors from fifteen thousand years ago, tirelessly migrating across continents, discovering fire, inventing the wheel, domesticating animals and building civilizations. However, during this process of social and cultural evolution they are continuously and mercilessly being hunted down by herds of giant, man-eating slugs. The sick and lame are picked off one-by-one and children are consumed as snacks as these rampant predators satisfy their appetite for food and carnage. During this particularly challenging time of pre-history, slugs occupied the ecological predatory niche later to be filled by wolves, bears, tigers and alligators. Their cunning and ruthlessness knew no bounds and those humans who survived were the ones who were the first to spot the looming shadows of the giant slug herd, the percussive shrill sound of their hunting cries, their erratic rapid movements across the savanna, and their staring eyes as they fixated their human prey.
Unfortunately, we’re unable to verify this historical scenario because giant slugs left no fossil remains, but they did leave a different legacy – our modern-day phobic dislike of slugs. Slug phobia is one of the commonest animal fears, and is often reported in the top ten animal fears worldwide (10). Have you ever been gardening with bare hands and – before you’re aware it’s happened – you’ve recoiled and shaken a slug from your fingers? Interestingly, women also tend to be significantly more slug phobic than men (11) – presumably because females were tastier to those ancient predatory giant slugs and so had to develop stronger avoidance responses.
The reason I’ve labored this fictitious example is because it helps to caricature a process that is very easy to slip into when it comes to trying to explain phobias. We’ve already noted that most people lack an understanding of how they acquired their fears. There is also a tendency for people to believe that they have had their fear for as long as they can remember. This failure to identify both a cause and an event that precipitated the fear can lead to the assumption that it is biologically pre-wired – “If I don’t recall it starting, then it must have been part of me forever”. This certainly rings true if the fear appears to be an adaptive one that could prevent harm, and fear of heights, water, snakes, spiders, etc. could all be construed in this way. The argument here is that heights, water, snakes and spiders have all been around for many tens of thousands of years, and could all be harmful in some way. Therefore, the genes of our ancestors who actively avoided these things would be selected for, and in this way a ‘fear’ or avoidance of them would be genetically handed down to us in the present day. This is certainly consistent with the fact that many people do exhibit fear of heights, water, snakes and spiders. But there is something disconcertingly easy about this type of explanation.
|Escape from the Man-Eating Gastropods|
Our story about the giant slugs provides one example of how this type of explanation might be fallacious. It is easy to believe how snakes and spiders (which can often be fatally venomous) might have been genuine threats to the survival and well-being of our ancestors, but surely not slugs? – And slugs are a very common object of phobic fears. It is also scientific bad practice to allocate a cause to an effect without providing any supportive evidence. For example, to my knowledge there is no substantial evidence that snakes and spiders ever represented a significant survival selection pressure to our ancestors, and this would be critical for the biological pre-wiring of any fears to these animals. We will certainly discuss the view that some aspects of phobic fear are biologically determined, but it’s hard to substantiate this down to the level of individual specific phobias. For example, we have biologically pre-wired startle reflexes that react to rapid movement towards us, rapid unpredictable movement, looming shadows, loud noises, and staring eyes and that should be quite enough to help us to detect most types of predator with some urgency. So why would evolution also want to equip us with what would be redundant pre-wired templates to detect and avoid very specific predators such as snakes and spiders?
It is probably useful at this point to introduce you to a character called Pangloss from Voltaire’s satirical novel Candide. Pangloss was someone who exhibited universal optimism best captured in the phrase “all is best in the best of all possible worlds”, and American biologists Stephen Jay Gould and Richard Lewontin coined the term ‘Panglossian’ to refer to the misguided view that everything present in the world today exists because it has a specific beneficial purpose. So, according to the panglossian view, the task for scientists is not to discover whether a given characteristic (such as a phobia) has an adaptive function, but to clarify how the characteristic has served an adaptive function. This panglossian view (that everything that exists must be adaptive) generates what is known as the ‘adaptive fallacy’, and this fallacy is that if you’re trying to generate reasons why something might be adaptive you can do that quite easily no matter what it is you’re thinking about, and this appears to be how some psychologists have considered phobias. That is, those phobias that are most common (e.g. heights, water, spiders, snakes, blood, injury, etc.) must be so common because they have an adaptive function – that is, they enable people to successfully avoid potentially harmful and threatening things.
I have argued many times in the past against these types of panglossian views which claim that phobias are evolutionary pre-wired adaptations – it smacks of a scientific ‘cop out’. In 1971, the famous American psychologist Martin Seligman wrote a short but very influential paper entitled “Phobias and preparedness” arguing that we hardly ever have phobias of things like pajamas, guns, electricity outlets, hammers, even though these things are likely to be associated with trauma in our world (12). Instead, we tend to have phobias of spiders, snakes, insects, heights, fire, deep water, etc. – things that have been around for a long time in evolutionary terms and were potentially harmful to our pre-technological ancestors. Seligman left us with the implication that most phobias are exaggerations of evolutionary adaptations that are pre-wired and that we are biologically prepared to acquire very rapidly given the appropriate learning conditions. This paper spawned a good twenty five years of research on the view that phobias were ‘biologically prepared’, and – even today – a glance at most introductory psychology text books shows that they still consider this evolutionary view to be an important potential theory of phobias. There was not a lot of solid evidence in Martin Seligman’s seminal paper to support the view that common phobias exist because of their adaptive evolutionary function, and as I recall, he only authored a couple of other tangential papers on this topic before moving on to other things, leaving us all to thrash around in the void trying to put some evidential flesh on these speculative bones. While adaptation through natural selection is one possible mechanism by which common modern-day phobias could exist, Gould & Lewontin also point out that some modern-day characteristics arise from random genetic sampling, and others may exist because they are associated with other structures and behaviours that do confer a selective advantage, and not because they directly increase survival themselves. But all these arguments assume that phobias are biologically pre-wired and merely contest the mechanism by which this has occurred.
To add a further element of skepticism to this adaptionist view of phobias, this view doesn’t provide a genuinely balanced picture of how phobias might be caused. If you look at the top ten list of predatory animals that kill human beings each year you won’t find the spider amongst those ten. But you will find animals such as lions, elephants, tigers and bears (13) – all are animals that people rarely acquire a clinical phobia to. It’s true, if you were confronted by one of these animals in a confined space you would be right to be very scared, and would be well advised to run like the wind at the first opportunity. But this adaptive fear is not the same as phobic fear. Very few people attend phobia clinics with debilitating fears of tigers or bears, hardly anyone gets a rush of fear-laden adrenaline when they hear the word lion in a conversation, and people just do not turn away in panic when shown a picture of an elephant. All of these reactions are certainly true of people with severe snake or spider phobia (and even in many cases, slug phobia!). Indeed, most of us happily send our children to bed with cuddly replicas of bears and make them watch TV programmes depicting tigers, lions and elephants as good-natured cartoon characters – hardly the stuff that would be expected if evolution was constantly telling to us beware of them.
To put this discussion into perspective, the adaptationist or evolutionary view of phobias might seem compelling because it appears to explain why common phobias focus on things that have been around for a long time (in evolutionary terms), why it might be adaptive to avoid or fear these things, and why sufferers can only rarely recall when and how their phobia started. However, it is still a highly speculative approach, and I would want to argue that it is almost certainly wrong, and that people acquire phobias during their lifetime through one of a number of very different psychological mechanisms and not because their phobias are biologically pre-wired. Finally, if we go back to our celebrity phobias, it’s hard to claim that phobias of more unusual things such as antique furniture, silverware, paper, door handles and mirrors are a direct result of evolutionary pre-wiring – mainly because these things have not been around for long enough for fear of them to become encoded in the gene pool. So they have probably been acquired during the sufferer’s lifetime. What is even more intriguing is that in most cases these fears have been acquired without the sufferer noticing, without any awareness of the conditions critical to their learning, and without any insight into how their thoughts and beliefs about the world have been manipulated and shaped. In 1950s speak, there is something akin to brainwashing going on here – but who or what is doing the brainwashing, and why should we want to become so fearful of things that – by any objective logic – we shouldn’t be frightened of at all?
PATHWAYS THROUGH THE MAZE
Whenever the causes of a phenomenon are concealed or difficult to identify we are often seduced into seeking magical or mystical explanations for them. Historically, phobias have been variously described as ‘manifestations of evil spirits and evidence of an imbalance in the hierarchical order of the universe’, an excess of black bile, emotional delirium, lucid insanity, a poor upbringing, or stomach ailments (14). In addition, Hippocrates believed that phobias were due to an overheating of the brain caused by a build up of bile. But it is easy to see how explaining the causes of phobias becomes difficult when even the sufferer is unable to provide significant insight into the acquisition process. Nevertheless, it is the purpose of science to provide rational and objective insight into nature and its causes, and the scientific path is the one we will steer.
Perhaps the first mistake when trying to understand phobias is to assume they are all the same thing, and so must have one single underlying cause. This homogeneous view is probably reinforced by the fact that the most important psychiatric diagnostic manual in the world - the Diagnostic & Statistical Manual of Mental Disorders (known as DSM) published by the American Psychiatric Association – defines specific phobias as a single diagnostic category “characterized by clinically significant anxiety provoked by exposure to a specific feared object or situation, often leading to avoidance behaviour” (15). So for diagnostic purposes chocolate and button phobia are lumped together with height phobia, spider phobia, slug phobia, and even phobia of antique furniture. Mrs. V, Billie Bob Thornton and myself are all burdened with the same descriptive diagnostic label for our very different anxiety-based problems. Yet everyone is different. Everyone’s experience of the world is different, including the route we steer through our lives and the way we perceive and interpret the world, and these individual differences will give rise to phobic experiences that are personal and unique. Nevertheless, scientific enquiry would have no value if were unable to pluck some common routes from the multitude of footpaths that define individual experience, and it’s my intention to give the reader a detailed, close-up insight into the various pathways that give rise to phobias. These pathways are often unusual and unexpected, but on reflection make psychological sense and fit with psychological fact. The subtlety of some of these processes explains precisely why many phobia sufferers are unable to understand how their fears were acquired, their thoughts were brainwashed, and their lives disrupted to such degree by fear and avoidance. We will also ask the question “What’s the point of phobias?” Is there a point to them, or are they just poisonous carbuncles that grow uncontrollably out of the body of our experiences? I have already suggested that they may not have the ultimate functionality that is bestowed by evolutionary selection – but do they have a more specific purpose – perhaps at the level of the individual and their own lives?
(1) L. M. Saavedra and W. K. Silverman, ‘Case Study: Disgust and a Specific Phobia of Buttons’, Journal of the American Academy of Child and Adolescent Psychiatry 41 (2002): 1376-1379.
(2) S. Rachman and M. E. P. Seligman, ‘Unprepared Phobias: “Be Prepared”’, Behaviour Research and Therapy 14 (1976): 333-338.
(3) Rose, Tiffany (September 3, 2004). "Interview with Billy Bob Thornton: Acting very strange". Independent.co.uk (London). Retrieved May 30, 2008.
(4) T. F. Chapman, ‘The Epidemiology of Fears and Phobias’, in Phobias: A Handbook of Theory, Research and Treatment, edited by G. C. L. Davey (John Wiley & Sons, Chichester, 1997).
(5) F. S. Stinson, D. A. Dawson, S. P. Chou, S. Smith, R. B. Goldstein, W. J. Ruan and B. F. Grant, ‘The Epidemiology of DSM-IV Specific Phobia in the USA: Results from the National Epidemiologic Survey on Alcohol and Related Conditions’, Psychological Science 37 (2007): 1047-1059.
(6) G. C. L. Davey, ‘Characteristics of Individuals with Fear of Spiders’. Anxiety Research 4 (1992): 299-314.
(7) E. Murray and F Foote, ‘The origins of Fear of Snakes’, Behaviour Research and Therapy 17 (1979): 489-493.
(8) R. G. Menzies and J. C. Clarke, ‘The Aetiology of Childhood Water Phobia’, Behaviour Research and Therapy 31 (1993): 431-435.
(9) R. G. Menzies and J. C. Clarke, ‘The Etiology of Fear of Heights and its Relationship to Severity and Individual Response Patterns’, Behaviour Research and Therapy 31 (1993): 355-365.
(10) G. C. L. Davey, A. S. McDonald, U. Hirisave, G. G. Prabhu, S. Iwawaki, C. Im Jim, H Merckelbach, P.J. de Jong, P. W. L. Leung and B. C. Reimann, ‘A Cross-Cultural Study of Animal Fears’, Behaviour Research and Therapy 36 (1998): 735-750.
(11) G. C. L. Davey, ‘Self-Reported Fears to Indigenous Animals in an Adult UK Population: The Role of Disgust Sensitivity’, British Journal of Psychology 85 (1994): 541-554.
(12) M. E. P. Seligman, ‘Phobias and Preparedness’, Behavior Therapy 2 (1971): 307-320.
(13) ‘Animal Danger’, available at http://www.animaldanger.com/most-dangerous-animals.php.
(14) S. J. Thorpe and P. M. Salkovskis, ‘Animal Phobias’, in Phobias: A Handbook of Theory, Research and Treatment, edited by G. C. L. Davey (John Wiley & Sons, Chichester, 1997).
(15) American Psychiatric Association, ‘Diagnostic and Statistical Manual of Mental Disorders, DSM-IV-TR’ (American Psychiatric Association, 2000).
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