Читать книгу Phobias: Fighting the Fear - Helen Saul - Страница 22

One of the good things about being an evolutionist is that you can never be definitively contradicted. Most scientists have their best work overturned within their own working life. They spend time trying to disprove other scientists’ ideas but they in turn are usually overtaken by someone else who contradicts or at least refines their work.

Believing in evolution gives a scientist some respite. Evolution took place over such a phenomenally long time scale that we can never recreate the same conditions and, ultimately, never know anything for certain. It provides a rather luxurious and permanent platform for scientists to stand on.

This does not mean that we have to accept the evolutionary perspective without question. With some lateral thinking, many ideas stemming from evolution theory can be studied scientifically. For example, evolutionists say that we are more likely to fear ancient rather than modern threats. If this is so, it should hold true for people of different races and cultures since we share the same ancestry and should therefore share the same fear programming.

A few small studies have produced some evidence for this. Researchers at a mental health clinic in Bangalore, India, found an incidence of phobias only a tenth of that in the West, a rate similar to that in other Indian communities. However, the vast majority of the phobias fitted the evolutionists’ model. Agoraphobia was the most common, closely followed by illness and social phobias. Animal phobias were rare, which is usually the case in clinics catering for people with the most seriously disabling problems. Scottish work found that more than two-thirds of a group’s phobias were relevant to ancient times. A Sri Lankan study used the same method and came up with virtually identical figures. This provides some backing for the idea that people in different parts of the world are similarly attuned to fear threats in the natural world.

More fundamentally, we cannot apply evolution theory to phobias at all unless we think cautious Stone-Agers were more likely to survive and produce offspring than their fearless friends. Fearfulness should have increased the chances of people passing on their genes to the next generation.

Coupled with this is the demand that ancient threats which still provoke fear today were capable of killing off people in large numbers, or at least reducing their chances of having children.

We cannot easily test this out in humans, but we can look for evidence in animals. Darwin noticed that birds are more ready to fear cats than people, presumably because they are at more risk from cats. More than one hundred years after Darwin, a psychologist at the University of Pennsylvania, Martin Seligman, became interested in how that should be. After all, both cats and people kill birds and it might be as well for the average bird to have a healthy respect for both.

Seligman said that birds are programmed to fear cats but not people. Somewhere in the depths of the bird’s tiny brain lies the knowledge or the instinct that makes them ready to fear cats. By contrast, they are essentially neutral towards humans. Birds may become afraid of humans, but are not likely to fear people unless they have been harmed or hounded in some way. Cats are natural enemies of birds and have killed off swathes of them down the ages.

Seligman said that birds are ‘prepared’ to fear cats but ‘unprepared’ to fear people. He said further that some animals are ‘contra-prepared’ to develop certain fears and never become afraid even if they have repeated bad experiences. For example, pigeons instinctively peck for food and in the laboratory they learn quickly to peck a lighted key if it delivers grain. But if the experiment is set up so that pecking the key prevents them getting grain, they do not learn, and continue pecking at the key even though they never get anything to eat. Pigeons normally have to peck to feed and they are contra-prepared to make an association between pecking and starvation. The hungrier they are, the harder they peck, and it never occurs to them that taking a rest might be the answer.

Similarly, they learn quickly to fly away to avoid a shock but only with great difficulty to peck a key to stop the shock. Again, it makes sense. Hopping or flying away from an unpleasant stimulus is a good idea. Pecking, as a rule, would not help.

Humans may also have degrees of preparedness to develop fears. Watson and Rayner’s experiment with Little Albert (described in the last chapter), showed that he learnt instantly to fear the furry rat, and many other similar objects, after the experimenters startled him with a loud noise while he was playing. He did not take against the scientists conducting the work, who quite clearly deserved it, which suggests he was more ready to fear animals than people. Another researcher gave children common household objects like curtains and blocks to play with, delivered a sudden loud noise, and found they developed no fear at all. In yet another similar experiment, children remained robustly unafraid of a wooden duck.

This may be an important hint as to how phobias develop. The brain’s hardwiring determines how ready we are to become afraid of something. It provides a kind of mould for our fears. Some animals and situations fit it well. Fears of them are instinctive and develop with the least provocation. Seligman initially said that objects or situations which threatened the survival of the species, such as insects, animals, heights or the dark, best fit the mould. Phobias develop without conscious thought, sometimes after a one-off event, and they are not easily extinguished. In addition, the more flexible process of experience, learning and observing others, means that we can become afraid of anything. Modern objects tend not to fit the mould and it takes very adverse circumstances to make us fear them. Phobias of objects can and do develop, but not easily. Seligman rather harshly suggested that people with these fears may have ‘talked’ themselves into it. Fear of cars or guns is unprepared, he says, our brains have no template for it, and it takes effort or severe experience to lodge the fear in our minds. We will return to this point later in the chapter.

For many years there was a fierce debate over whether people and animals were born with fears or developed them later, but in the 1960s researchers demonstrated that laboratory-reared monkeys are not at all afraid of snakes. Monkeys who have spent even a short period in the wild are extremely afraid. It is highly unlikely that all of the once-wild monkeys had had a traumatic experience with a snake, so this was puzzling and it seemed that at least some of the monkeys must have acquired their fear vicariously, through seeing another monkey acting scared – a kind of fear by proxy.

Susan Mineka and colleagues at the University of Wisconsin put a monkey’s favourite treat, such as a marshmallow or raisin, on a ledge behind a transparent box. There was a real or toy snake in the box and the monkey had to reach over the snake to get the sweet. The more afraid the monkey was, the more reluctant it was to stretch over the box, and Mineka found that the fearless laboratory-reared animals grabbed the treat where the once-wild monkeys refused it.

Some laboratory-reared monkeys had lived with their previously wild parents all their lives. This was obviously not sufficient for them to acquire the fear of snakes – they seemed to need some experience for the fear to develop. When the laboratory-reared monkeys were allowed to watch older, wild-reared monkeys cowering from the snake, the vast majority developed the same reaction themselves, within minutes. They mimicked the screen monkey’s behaviour, clutching or shaking the cage, grimacing or threatening.

Mineka then attempted to make monkeys fear flowers or rabbits, objects that could never pose a threat. One video showed a monkey afraid of a snake and another was edited so that the same monkey was apparently afraid of a flower. Fearless young monkeys watched the tapes and afterwards, those who had seen the snake tape avoided snakes, but those who had seen the flower tape remained unconcerned by flowers. It was clearly easier to induce a fear of snakes than flowers. A similar experiment demonstrated that the monkeys were more ready to fear toy crocodiles than toy rabbits.

This is powerful evidence that creatures really are programmed to fear certain things. These monkeys were born in laboratories and had never previously encountered snakes, flowers, crocodiles or rabbits. Mineka and Cook concluded that it was highly likely that the difference in the monkeys’ reactions was somehow in-built, or ‘phylogenetic’. In other words, snakes and toy crocodiles are a better fit for the mould in the monkey’s brain.

Monkeys may not be born afraid of snakes but any sort of demonstration is enough to provoke their fear. It makes sense from the evolutionists’ point of view. Animals may not get a second chance in the wild and mistakes can be fatal. It could be that monkeys that quickly learn to be afraid of snakes or crocodiles have a survival advantage over their bolder companions. They are more likely to avoid these animals and therefore to survive and produce offspring. They will pass on the tendency to fear and, over generations, natural selection would increase the proportion of all monkeys inclined to fear snakes or crocodiles.

Work like this could not be done on people because we would all have experience of any object the researchers chose. But it might still be possible to draw human parallels from the work. Monkeys are not people, but our learning processes are surprisingly similar.

Take a country like Britain, where we have only one poisonous snake, the adder, and virtually none of us has ever seen it. Yet many of us are afraid of snakes. Why? Mineka’s work suggests, if humans are anything like primates, it will not take much exposure to snakes for a strong fear to develop. Monkeys developed permanent fears from watching videos and people probably do, too. We could be watching from a distance as someone else reacts to a snake or, much more likely, see someone shuddering at them in a film or on TV. From a very young age, we learn of Little Miss Muffett being frightened away by the spider, or the farmer’s wife shrieking in terror at three blind mice.

Role models are powerful, especially – according to Mineka – if they are older and more dominant. Her models did not have to be related to the young monkeys but it helped if they knew each other. This suggests that parents or other influential adults – even television and film role models – could pass on their fear to children. Mineka believes that if adults have phobias, they should not confront snakes, spiders or whatever it is they fear in front of children. We might expect it to be a bad thing for parents to blatantly avoid objects or situations, but this study suggests that it is worse for children to see their parents visibly disturbed.

There is a plus side to this work. Mineka found that monkeys can be immunised against developing a fear and learn not to be afraid. A model monkey who was unafraid of a snake made a lasting impression on the naive monkeys. They apparently got the message that snakes are not to be feared and it prevented the later development of fear. If, afterwards, they saw another monkey afraid of the snake, three-quarters of the young monkeys remained fearless. This suggests that adults who show no signs of fear when dealing with spiders or snakes exert a powerful influence on children and may prevent them developing these fears.

Mineka’s work tells a neat story, based around the assumption that snakes and crocodiles were real threats to monkeys and killed them off in huge numbers. Monkeys who were afraid of these animals therefore had a survival advantage. Unfortunately, the evidence does not fully back up the theory. The rhesus monkeys used by Mineka evolved in India, where cobras and other poisonous snakes could have been dangerous. However, there is less evidence that crocodiles would have been a danger. Crocodiles might be feared because of their reptilian similarity to snakes, but this seems rather to weaken the argument.

It partly hangs on how the brain recognises threatening animals or situations. The brain could have a full picture of snake or crocodile irrevocably programmed into its hardwiring. Alternatively, features like smell, sliminess or sudden movements may be what we are on our guard for.

People with phobias often give vivid descriptions of what they fear; the appearance, feel or thought of the animal. Abrupt, jerky, unpredictable movements are frightening. Sliminess disgusts us. Even babies dislike strange, inhuman appearances. Jamie Bennet-Levy and Theresa Marteau in London asked a group of people about rats, cockroaches, butterflies, frogs, rabbits, spiders, blackbirds and other small animals. The volunteers rated each creature for ugliness, sliminess, speed and how suddenly they appear to move. Another group said how afraid they were of the various characteristics and how near they would go to each animal. Not surprisingly, the more harmful the animal was, the more afraid people were and the less prepared to get close. Physical characteristics, especially ugliness, also deterred them. The volunteers in the study said that ugliness was a composition of sliminess, hairiness, colour, dirtiness, number of limbs or antennae, compactness of body and the relation of the eyes to the head. In other words, how different the animals’ appearances were from humans. Touch and sound came into it as well and people hated the thought of a spider running up their leg or in their hair.

Similar work in the Netherlands also concluded that the more animals differ from humans, the more we fear and avoid them. Lack of predictability or control of the animals makes things worse. People are inclined to be suspicious of all things strange and seem ready to fear features of alien species. This suggests that the human brain is set up to notice unpleasant characteristics and probably does not contain a full picture of certain dangerous animals.

It is puzzling, then, that Mineka found monkeys quick to fear toy snakes and crocodiles, which do not have strange smells or movements. Suffice it to say that not even evolutionists can claim that all evidence points the same way.

The inner workings of the brain remain mysterious, despite increasingly sophisticated work such as that described in chapter 4, on neurophysiology. Tracking down the unconscious requires ingenuity and a Swedish group led by Arne Öhman and Joaquim Soares hit upon the idea of using subliminal images. The approach has a certain history. A classic but flawed experiment in the 1950s flashed up a message urging cinema viewers to drink Coca-Cola. The message disappeared so quickly that viewers had no idea their film had been interrupted, but this brief exposure was enough to make them inclined to buy more of the drink. However, the film itself was about food and drink and the results were inconclusive. In any case, sadly for the advertising industry, such tactics remain illegal.

In the laboratory, Öhman and Soares had more freedom and flashed pictures of spiders, snakes, flowers and mushrooms on screen. They recorded skin conductance on volunteers’ hands. It is a measure of arousal in the autonomic system and changes when people have any sort of anxiety reaction. Volunteers responded to the sublimal pictures. For example, people with spider phobias reacted more strongly to pictures of spiders than anyone else. They did not know what they had seen but nevertheless had a physical reaction. Like the cinemagoers who suddenly had an urge to drink cola, the volunteers unconsciously registered the picture they had seen.

The researchers then tried to make the volunteers artificially phobic and gave their finger an unpleasant electric shock as the flashed pictures appeared. Some received the shock when they saw the snake picture, others when they saw the spider, flower or mushroom pictures. They all reacted to the picture paired with the shock.

Volunteers then saw the flashed pictures again but without the shock. Responses to flowers and mushrooms were eliminated but responses to snakes and spiders endured. None of the students had any conscious idea what they were reacting to, but responses to snakes and spiders were consistently more resilient than those to flowers and mushrooms. It implies that the unconscious can somehow pick out fearful stimuli.

By the time we recognise a spider or snake, our unconscious is already generating a rising tide of arousal which puts us on red alert, said Öhman and Soares. This heightened awareness makes us more likely to feel defensive and afraid. Phobics cannot control their fear voluntarily because the initial reaction is unconscious and under the control of deeper, ancient parts of the brain.

These exciting results encouraged the researchers to look at another type of danger: threatening human faces. Threats from predators such as snakes are important to the most primitive creatures and defences would have evolved early. Social threats affect more sophisticated creatures and would have evolved much later. Therefore the relevant information may be processed in the higher brain, the cortex, which carries out more complex functions and developed late in evolution. This ties in neatly with Darwin’s earlier assertion that blushing developed comparatively recently.

The cortex has left and right halves with different functions. If social submissiveness is processed in the cortex, our reaction may depend on where the human face is when we see it. Negative emotion and perception of faces are believed to be processed in the right hemisphere in right-handed people. Information from the left side of someone’s visual field is also processed in the right hemisphere. If someone sees an angry face in their left visual field and the information goes straight to the hemisphere adapted to process it, they may react more vigorously than if the information is sent to the other side of the brain. There are lots of ifs here, but volunteers did react more strongly to a flash picture of an angry face when it was shown to their left rather than right visual field.

If fear of small animals is processed by the oldest parts of the brain, deep down where there is little difference between right and left sides, there ought to be little difference whether the slides are shown to the right or left visual field. This turned out to be true. People’s reactions were similar, regardless of where the slides were flashed up, which supports the idea that this reaction developed early in evolution.

Information on ancient threats is processed first by ancient parts of the brain, according to Öhman. Colour, texture, smell or type of movement may be sufficient to trigger this automatic response and we react immediately and instinctively. We may even have special pathways in the brain for transmitting information about ancient threats, pathways which existed before sophisticated reason and logic and which are physically distinct from those carrying conscious thought. This ancient reaction can produce a groundswell of emotion which colours our thoughts even before the higher brain has engaged and started to make us aware of a potential threat.

Like Seligman, Öhman suggests that responses to ancient threats are easier to establish and harder to extinguish than responses to unnatural or modern cues. It certainly provides a neat explanation for the reactions that may underpin many phobias. The reality is, unfortunately, less straightforward and Öhman’s results have proved fragile. There are many detractors, and even some supporters of the theory have been unable to come up with the same answers.

An American group led by Edwin Cook, himself an advocate of evolution theory, set out to repeat some of Öhman’s work. They used a similar set-up and were surprised to find that reactions to spiders and snakes were as easy to induce as modern fears of guns. It was also equally easy to eliminate them. In direct contrast to Öhman’s predictions, reactions to spiders disappeared as quickly as reactions to guns.

Cook used an unpleasant noise rather than an electric shock, so his volunteers received no tactile stimulus. When he added a vibratory stimulus to the hand, his experiments started to distinguish between modern and ancient threats, but the results were unconvincing. There was still no difference in acquisition or extinction of fears, though Cook found an increased heart rate associated with spiders or snakes and not guns.

When Cook followed Öhman’s protocol to the letter, he confirmed that fear of ancient objects was more resilient than that of modern threats. But the difference was slight. Overall, Cook’s work provided only flimsy support for Öhman and also raised questions about the relevance of some features of the experiment.

Cook was not the only one to have trouble replicating Öhman’s work. An American duo, Richard McNally from Chicago medical school and Edna Foa from Pennsylvania, changed mushrooms for strawberries in Öhman’s experiments. This was enough to eliminate differences in reactions to threatening and non-threatening objects. Even people who were phobic of snakes or spiders before the experiment reacted to strawberries just as strongly.

Perhaps the greatest disappointment to advocates of the theory is that it has little impact in the phobia clinic. Despite the predictions of Seligman and Öhman that fears of ancient threats are more easily acquired, more deeply ingrained and harder to reverse, this seems not to be the case. The Scottish and Sri Lankan studies mentioned earlier both found that the vast majority of phobias in these two quite different countries are related to ancient threats. However, neither study linked phobias of ancient threats to more severe impairment. Zafiropoulou, who led the Scottish study, said that success of treatment was unrelated to the type of phobia and suggested that the concept of phobias as vestiges of our ancient past is little practical use.