Brain Finding Purpose Mental health

What makes us focused, motivated and purposeful? Our biology.

Woman focusing
Dr. Ralph Lewis
Written by Dr. Ralph Lewis

We all want to have a strong sense of purpose. What generates this purposefulness? Undoubtedly a vast and complex array of psychological and social factors shape it. But fundamentally all of these factors are mediated by motivational and reward circuitry in the brain, which is dependent on chemical transmitters. This circuitry is susceptible to disruption by physical damage, drugs and disease. Sense of purpose, like all other human behaviour, is fundamentally a physical, biological function.

To understand purposeful behaviour, we first need to understand attention. Attentional focus is essential for tasks requiring sustained, effortful, goal-directed motivation – the kind of motivation needed in order to succeed at school and in many skilled jobs in a modern society. People differ in how naturally focused they are, and in their ability to sustain this kind of motivation. Like all traits, there is a spectrum of attention span in the general population: some of us just naturally have a longer attention span, and some of us naturally have a shorter attention span. Like most traits, this is partly determined by our genes.

In the environment in which our species evolved for most of its history (think hunter-gatherers), longer or shorter attention spans would both have been advantageous in different situations. All types of individuals were needed for the group to survive and thrive.


“Sense of purpose, like all other human behaviour, is fundamentally a physical, biological function.


Modern societies have created a very artificial environment that is highly structured and organized, with division of labour into highly specialized tasks. Many of those tasks require sustained attention and are not particularly exciting, social or varied. Many aspects of our modern environment, and many occupations, favour people with longer attention spans: people who can persist with low-stimulation tasks that require sustained effortful focus, attention to detail, organization, patience, self-discipline and the ability to work towards very delayed or abstract rewards.

People with shorter attention spans who need more varied stimulation to keep them engaged, and who are more interested in the “big picture” of their surroundings than the small details in front of them, tend to struggle to maintain effortful focus and to sustain motivation for ‘boring’ tasks.

People with especially short attention spans are often diagnosed with ‘Attention Deficit Disorder’. ADD is perhaps better understood as part of the normal diversity of traits in a human population, rather than a ‘disorder’ as such. But having an attention span toward the left hand side of this “bell curve” is disadvantageous when facing the more attention-taxing demands of our skewed modern environment.

Degenerative disease processes such as dementia, and certain kinds of brain damage (especially damage affecting the frontal lobes), can profoundly impair focus, motivation and the ability to be goal-directed. Major mental illnesses like schizophrenia can cause the same kind of severe apathy. Depression too can be temporarily debilitating, due to a loss of the feeling of reward that normally reinforces motivation. A variety of chemicals (street drugs and prescription drugs) can either impair or enhance focus and motivation.

Actually, people who are excessively focused (at the far right end of the attention span ‘bell curve’) have difficulties too. They tend to be finicky, obsessive, inflexible and perfectionistic, and may tend to miss the big picture.

Key parts of the brain’s attention and motivation circuitry involve evolutionarily primitive regions located deep in the brain (mesolimbic circuit) common to many animals, as well as evolutionarily advanced parts of the brain that are more unique to humans and our close primate relatives, located behind your forehead (called the prefrontal cortex).

Human motivational circuitry employs the same mechanistic molecular system common to evolutionarily primitive animals. For example, when the neurotransmitter chemical dopamine is stimulated in the brain, it marks a stimulus as important and attention-worthy, and reinforces behaviour associated with the increase in dopamine. This has a focusing, motivating and rewarding effect. Our goal-directedness is really just a vastly elaborated version of what very much simpler animals and organisms do. So, you might say that our wondrously complex human sense of purpose is an extravagant embellishment of nature – kind of like the peacock tail, shaped entirely by evolutionary pressures into something beautifully elaborate. But like all products of evolution, it is an imperfect biological system and is vulnerable to harsh failure.

Sense of purpose is not just an abstract psychological or philosophical notion. It is a biological function entirely dependent on the physical brain. In humans, all this is enriched by conscious self-awareness, the sense of being a permanent unified self, and the sense of having free will. Our intuitions tell us that surely these must be non-physical qualities. And yet, they too are utterly dependent on imperfect physical processes and are tragically diminished and disassembled by disease or damage. These are topics we will return to in later blogs.

About the author

Dr. Ralph Lewis

Dr. Ralph Lewis

Dr. Lewis is a psychiatrist at Sunnybrook Health Sciences Centre in Toronto, Canada, and an assistant professor in the Department of Psychiatry at the University of Toronto. His clinical work focuses particularly on two areas: youth psychiatry and psycho-oncology.

» Read his blog series, Finding Purpose