There’s an old joke that goes something like this: How many psychologists does it take to change a light bulb? Answer – One. But only if the light bulb wants to change! It’s a cute joke but in the context of discussions about mental health disorders, a better answer might be: One. But only if the psychologist knows when the light bulb needs changing.

Image courtesy of Master isolated images at

Image courtesy of Master isolated images at

People don’t usually change light bulbs that work. A point as obvious as this is easy to miss: to know when a light bulb needs changing is to know the difference between when the light bulb is broken and when it is working normally.

This simple principle can be applied generally. Knowing when something needs fixing or correcting necessarily implies knowing what something does or what the normal functioning state of that something is. If you were walking along the beach one day and, washed up on the shore was a strange object you’d never seen before, how would you know whether it worked or needed fixing? Surely to make this assessment you would have to know what its function was. What does it do? It is only with an appreciation of what something does that judgements can be made about whether or not that something needs fixing.

Simple though it may be, this principle appears to have been ignored when it comes to mental illness. Discussions and debates about how best to diagnose or otherwise identify mental disorders are conducted in the absence of any agreement as to what the state of normal functioning is. How can abnormal, dysfunctional, or disordered be understood other than by reference to that which is normal, functional, or ordered?

Defining normal should be primary. Yet, without an understanding of what state or condition people have deviated from, and should be returned to, we do such things as: administering powerful medications; electrically inducing seizures; and, teaching activities to alter the content of cognitive processes. In the midst of all these activities many people manage to reduce their psychological distress and resume living the life they wish to live. A large number of people, however, do not. A conservative conclusion from this situation would be that, currently, without a robust understanding of human functioning, our treatments help people serendipitously rather than systematically.

In many ways we appear to have placed the cart in front of the horse. Our first task should be finding normal. What is a “normal” person? What does a normal person do? Is it normal to behave abnormally? If defining normal is an insurmountable problem, then surely defining abnormal becomes impossible or nonsensical (or both).

Two examples will help illustrate this point. Apparently, fluoxetine achieves its effectiveness by altering serotonin activity in the brain but, to do this, it has to impair rather than improve the negative feedback mechanism that normally keeps chemical concentrations at particular levels (Whitaker, 2010). Whitaker says this about the way in which fluoxetine achieves its antidepressant effects “the medicine clearly doesn’t fix a chemical imbalance in the brain. Instead, it does precisely the opposite. Prior to being medicated, a depressed person has no known chemical imbalance. Fluoxetine then gums up the normal removal of serotonin from the synapse, and that triggers a cascade of changes, and several weeks later the serotonergic pathway is operating in a decidedly abnormal manner.” (p. 81). So, in this instance, we have a treatment for psychological distress working by interfering with normal brain processes. On the SANE Australia website, however, the following information is provided under the heading How does ECT work?: “The brain works through complex electrical and chemical processes. These are affected by mental illnesses, so that they don’t work properly. Like medication, ECT works on these processes so that they operate more normally again and symptoms are reduced.” ( In this instance it is claimed that ECT restores processes to normal functioning. Or, at least, assists them to function “more normally” whatever “more normally” might be.

So we seem to have a situation whereby fluoxetine works by retarding normal processes, and ECT works by restoring them. This information, however, is provided without any articulation of what “normal functioning” is. What is the normal level of serotonin in the brain? What is the normal operation of the complex electrical and chemical processes that have been supposedly affected by mental illness and are somehow restored by ECT?

Statements of normal and abnormal are scattered throughout the mental health literature. Mental disorders are considered by some to arise from disordered brain circuits (Insel, 2012) and cognitive therapy apparently works by modifying dysfunctional beliefs and attitudes. But what is an ordered brain circuit and what are functional beliefs and attitudes?

If my responses on a standardised questionnaire provide a score that indicates I’m in the normal range for depression or anxiety or some other form of psychopathology, does that mean I’m normal? If I score outside this range am I abnormal? What if I hear voices? What if I pursue career goals at the expense of family relationships or family relationships at the expense of career goals? What if I prefer to feel my arms and legs moving rather than sitting still in a desk in a row of desks? What if I want to make my own decisions rather than follow other people’s instructions? What if I get upset because I like to spend time with my primary caregivers instead of being left with strangers for long periods during the day? What if I think I’m normal, but other people don’t?

Also, only a proportion of people experiencing problems are ever diagnosed as being abnormal or disordered. To receive a psychiatric diagnosis, and be deemed to have an abnormal, disordered, or dysfunctional psychological state, you have to report or otherwise display certain experiences (behaviours, thoughts, feelings, images, and so on) and you have to report or otherwise display them to someone who has the authority to diagnose. Conceivably then, there are lots of people who might be judged to have disordered thinking or be otherwise abnormal but never acquire a psychiatric diagnosis. Ironically, once people receive a psychiatric diagnosis it is rare for them to be undiagnosed regardless of how normally they might behave subsequent to the diagnosis.

Without any agreed upon position regarding normal human functioning we have developed models and other explanations of abnormal human functioning. And, by and large, these models and explanations are based only on the people who come into contact with mental health services or mental health research activity. So we are currently discussing and debating the best way to classify what is wrong without any clear picture of what is right.

Perceptual Control Theory (PCT; Powers, 2005, 2008; offers one suggestion of normal functioning: normal functioning is a process of control. Entities that live are organised as control systems. Problems occur when control processes are interrupted. A strength of PCT, therefore, is that it starts from a perspective of what could be considered normal or routine.

Perhaps PCT won’t be the way of the future. Perhaps there is a more accurate, more precise way of characterising the process of living. That, surely, is a matter to be settled empirically rather than through appeal to opinion or authority.

What is a normal, garden-variety human being? How does one go about being human? Without robust answers to these questions, discussions of abnormality or psychopathology will be fatally constrained in their ability to bring about lasting and effective solutions. Finding normal, and understanding how it is achieved and maintained, is perhaps the most pressing issue of our time.


Insel, T. R. (2012). Next-generation treatments for mental disorders. Science Translational Medicine, Oct 10, 4(155). doi: 10.1126/scitranslmed.3004873.

Powers, W.T. (2005).  Behavior: The control of perception (2nd ed.). New Canaan, CT: benchmark publications.

Powers, W. T. (2008). Living Control Systems III: The fact of control. New Canaan, CT: Benchmark.


Tim Carey

About Tim Carey

Tim is a Professor in Mental Health at the Centre for Remote Health in Alice Springs, Australia where he conducts mental health research and provides a clinical psychology service within the public mental health service. He has a PhD in Clinical Psychology from the University of QLD (Australia) and an MSc in Statistics from the University of St Andrews (Scotland). He has over 100 publications including books, book chapters, and peer-reviewed publications in scientific journals and has presented his work at national and international conferences. Tim has developed a transdiagnostic cognitive therapy called the Method of Levels (MOL) which adopts a patient-centred view of mental health disorders and seeks to help patients resolve the distress underlying particular symptom patterns rather than focussing on the symptoms themselves. He has also pioneered a patient-led system of service delivery in which patients determine the frequency and duration of treatment sessions. His interests in mental health centre around the importance of control to psychological wellbeing and service provision and he prioritises the perspective of the individual in understanding psychological distress and helping in its amelioration.