What is 'abnormal' anyway?
In the most 'scientific' of the sciences, physics, we talk about 'universal laws'. These are statements that describe the functioning of the natural world in its most fundamental sense. I commute to work by car and unfortunately drive for quite long distances on motorways. So my journey to work (like, I suppose, everything else in life) depends on the operation of the laws of physics. When it rains, we often see collisions and other accidental tragedies; the roads are slippery, it is harder to see. When people have accidents, the police investigate the probable or likely cause of the incident for legal and insurance purposes. Their analysis includes human factors, but also includes complex physics. To work out why a tragedy has occurred, the investigators will calculate things like the velocity of the vehicles involved, coefficients of friction between rubber and tarmac, reaction times calculated using equations of acceleration and deceleration, the role of centrifugal forces, tyre pressures and 'footprint', the role of aquaplaning, lift, etc. They will measure elements of the physical world; the weight of the vehicles, radius of turns, the slope of ascents or descents, whether the conditions were wet or dry, the temperature, tyre pressures, the condition of brakes and the nature of the road surface. All these aspects of physics are important; they explain why accidents happen. But road traffic investigators don't use a special branch of physics called 'abnormal physics'. We don't expect scientists to apply one special branch of physics to car crashes and differentiate this from the laws of physics that apply to 'normal life'. There is not an 'abnormal coefficient of friction' that leads to car crashes and a 'normal coefficient of friction' that keeps us safe. Instead, and wisely, we recognise that it is important to understand the universal laws of physics - such as friction - and then use that understanding to help design safer roads and to drive more safely as individuals.
The laws of psychology are similarly universal. Psychological principles apply to health and well-being and to distress and problems. There simply isn't an 'abnormal psychology' that applies to distress or explains 'illnesses' and a different 'normal psychology' that applies to everything else. There is just psychology. Everybody makes sense of their world, and does so on the basis of the experiences that they have and the learning that occurs over their lifetime. We all use the same basic processes to understand the world, even if we come to very different conclusions. The patterns and contingencies of reinforcement - rewards and punishments - shape us all: the basic psychology of behavioural learning is universal. We all learn to repeat those things that are reinforcing, and we all withdraw from things that cause us pain. We all construct more or less useful frameworks for understanding the world, and we all use those frameworks to predict the future and guide our actions. That's true for someone who has learned to trust people, and it's true for someone who has learned to distrust them. Middle-aged people from the UK will remember Eric Morecombe on the piano saying that he's playing 'all the right notes ... just not necessarily in the right order'. As I'm writing this book, I'm using common words and the standard 26 letters of the alphabet, but hopefully I'm putting them together in a novel sequence. So it is with our learning about the world and how that learning affects our emotions. We're all using the same processes of learning and understanding, and those processes have similar effects on our behaviour and emotions. However, because no one is exactly the same as anyone else, or has exactly the same experiences, we all make sense of the world in slightly different ways, with different consequences. But that's entirely different from suggesting that there is some kind of 'abnormal psychology'.
So I believe that we all share one psychology; it's wrong to separate 'normal' from 'abnormal'. But it's also true that we can't make that separation in our everyday experience. There's a frequently quoted statistic that mental health problems will affect one in four of us in our lifetimes. It's often used to campaign for greater understanding and greater funding. But it's a curious statistic. We ALL have mental health problems. We ALL get anxious or depressed from time to time, hear our names mentioned when nobody's said anything. So we all - ALL - have mental health, and we all have mental health problems. The real question is, how severe, how long-standing, how distressing are those problems? The 'one-in-four' statistic may be misleading and distracting, as it gives the impression that there are two groups of people: those with mental health problems and those without. It refers to the number of people whose problems would meet the diagnostic criteria for a mental health problem.3 Given that mental health professionals seem to be lunging headlong towards labelling everything and everybody, that statistic is meaningless. Except . .. it illustrates how common these problems are. And that's important.
Even complex, difficult, distressing and perplexing psychotic experiences are very common in the general population. Many, many people hold beliefs that others consider strange or bizarre (for example, belief in UFOs, alien abduction, ghosts or telepathy). We all feel suspicious of other people from time to time. It's a standing joke that professors all think that their academic colleagues are out to get them (of course it's because we know that they are!). The extreme state that we call 'paranoia' or 'persecutory delusions' is on a continuum with these feelings of suspiciousness. There is natural variance between people in this respect. We've all had different experiences and we have different reasons why we might have become distrusting or suspicious. We all know people who are 'touchy' in this respect. And we've all been in situations where it makes sense to be particularly vigilant (walking down an inner city street at night, for example) and in such situations it is easy to be frightened by even the most innocent things.
So it's not surprising that surveys of the general population routinely reveal that somewhere between 10% and 15% of people have had a hallucination at some point in their lives. Although only about one person in a hundred receives a formal diagnosis of 'schizophrenia', surveys suggest that 'psychotic-like' experiences are as much as 50 times more common than this. This means that perhaps half of us have heard or seen things that aren't there, have been convinced by things that other people regard as strange or bizarre, or have been unreasonably suspicious of other people. We know that extreme circumstances, such as sensory or sleep deprivation, can lead to paranoia and hallucinations. And there are many people who have strange experiences (such as visions, auditory hallucinations, or profound spiritual experiences) but interpret them as spiritually enriching. Different cultures have very different expectations in terms of what is considered normal, as well as hugely different ways of describing things. In many cultures, it is routine to describe dead people being present with you in day-to-day life. Some of the differences are to do with use of language: people describe similar experiences differently and the same words (or their nearest translations) can mean something else in another culture. But different cultures also have fundamentally different beliefs as to what constitute the 'symptoms of mental illness' as opposed to normal experiences or religious and spiritual experiences (such as the presence of ancestors, the everyday tangible presence of God, the effects of divine intercession or spirit possession). In some cultures, things that the West sees as problems are seen as spiritual gifts to be respected and protected, for example Shamen or mediums. Although psychotic experiences can sometimes be extremely distressing and disabling, for other people, they may even be life enhancing. For some people, they are both at different times, or even perhaps at the same time.
At this point in the argument, my colleagues (both psychologists and psychiatrists) often point out that a diagnostic approach is useful because there are very significant differences between 'real' problems that are 'hugely distressing' and the normal ups and downs of everyday life. That is absolutely true. We all get miserable from time to time. When things go wrong in my life - when a relationship fails, or I fail at work or someone close to me is seriously ill - I (and we all) sometimes feel low, unmotivated, have problems sleeping etc. (i.e., experience some of the so-called symptoms of depression). I am not, of course, claiming that is in any sense as serious a problem - is the same problem - as somebody who has been depressed for years, has harmed themselves, is reliant on medication and is contemplating taking their own life. But I am saying that the experiences and emotions lie on a continuum. Many important things, life-threatening things, lie on continua. Many of us, these days, are overweight. Some people could do with losing a few pounds, but some people are in serious and acute danger. These issues lie on continua, but it does not follow that, because there is a continuum of experiences, that the one extreme is somehow no longer being differentiated from the other. My boss, the Vice-Chancellor, earns a very great deal more than the cleaners at my university (he earns quite a lot more than me). Clearly, salary is something that lies on a continuum (you just keep adding ?10 notes one after the other for a very long time), but nobody is saying that this is equivalent to saying that everybody earns the same amount. So the distressing and life-threatening experiences that fall under the umbrella of 'mental health problems' are serious, real and occasionally life threatening. But they aren't unique and different parts of the human experience. They lie on continua with other common experiences, and the same psychological principles apply.