Have you ever wished you could be better organised or more sociable? Or more inventive and original? Perhaps you’re a constant worrier, and you’d prefer to be a little more carefree? If any of these thoughts ring true, you are far from alone. A number of surveys show that at least two-thirds of people would like to change some element of their personality. In the past, such desires appeared to be futile. Our personalities were thought to be formed in childhood and to remain fixed throughout lives. Like the proverbial leopard that could never change its spots, our virtues and flaws were believed to be woven into the fabric of our psyche. Recent scientific research, however, confounds this expectation of personality’s permanence. With the right psychological strategies, and enough effort, many people can successfully mould their core traits into the shape they desire. There are many ways of measuring personality, but much of the research has centred on five specific traits that are thought to comprise our most fundamental characteristics. Known as the “big five”, they are: extraversion – how outgoing and sociable you are; conscientiousness – how organised and disciplined you are; agreeableness – how concerned you are with social harmony; neuroticism – how nervous and sensitive you are; and openness to experience – how imaginative and curious you are. In thousands of studies, psychologists have shown that people’s scores for the big five can predict important outcomes in a range of areas. People who score highly on conscientiousness, for example, get better grades at school and earn more. Those who score highly on neuroticism, meanwhile, are more predisposed to stress, which has knock-on effects for their health. Our genes almost certainly play a role: it’s why people’s personalities often reflect their biological parents’ traits, and why identical twins are more similar than non-identical siblings. The influence of our social environment was thought to end in early adulthood, as the brain reached maturity. If this were true, you would not expect adults’ personalities to change naturally over time, and it wouldn’t be possible to mould personality at will. Yet that is exactly what psychology professor Nathan Hudson and his colleagues have shown with a series of groundbreaking studies. Their interventions typically involve prescribing regular activities that reflect the personality traits people wish to adopt. An introvert who wished to be more extraverted, for example, might have the goal of introducing themselves to a stranger once a week, or making small talk with the cashier at their local supermarket. Someone who wished to be more conscientious might be asked to carefully proofread an email before sending it, or to write a to-do list before going to bed. A neurotic person might be given exercises to improve emotional regulation, such as writing down feelings when they threaten to become overwhelming. While these tasks may seem insignificant, the aim is for the thinking patterns and behaviours they generate to become habitual. And the evidence so far suggests it works remarkably well. In one 15-week trial of nearly 400 people, participants accepted an average of two challenges each week. Provided they actually completed those tasks, their traits shifted in the desired direction, according to a standard big five questionnaire. Similarly exciting results could be seen in a later experiment, which used a smartphone app to coach participants in their desired big five traits. Crucially, this study involved a much larger sample – 1,500 people. And in addition to the typical self-report questionnaires, it asked participants’ friends and family to rate their personalities before and after the intervention. The differences were still apparent three months after the experiment had ended. As Aristotle argued more than 2,300 years ago, we become what we repeatedly do. The unexpected malleability of our minds should be good news for anyone who wishes they were a bit more sociable, organised, or happy-go-lucky. Another potential benefit is that awareness of this research could help improve mental health. Conditions such as depression and anxiety are often characterised by feelings of helplessness: people believe negative feelings are just part of who they are, and there is little they can do to change them. This can compound the sadness and worry they face, and may also make them more resistant to treatment or making lifestyle changes that could speed their recovery. What if educating people about their potential for personality change placed them on a more positive trajectory? To test this idea, Jessica Schleider, assistant professor of clinical psychology at Stony Brook University, New York, and John R Weisz, professor of psychology at Harvard, selected a group of around 100 adolescents who had previously shown signs of anxiety or depression. They took a brief computerised course that explained the science of brain plasticity, alongside statements from older students, who described the ways they had grown over their school years. They were then given worksheets to consolidate what they had learned. When Schleider and Weisz checked in on the teens’ mental health nine months later, the students reported a significant decrease in their anxiety and depression compared with those who had instead taken part in a course on “emotional expression”. The same strategy has since been tested in other settings, with larger numbers of participants, that have produced equally positive outcomes. Teaching people about personality growth is not a panacea, but these results suggest that it may be a useful tool to help build greater psychological resilience. Whether you are wrestling with serious issues or simply want to polish off your rougher edges, it is reassuring to know that character is ultimately within your own hands. DNA and our upbringing may predispose us to certain traits, but we also have the power to shape our future selves. David Robson is the author of The Expectation Effect: How Your Mindset Can Transform Your Life. Further reading Be Who You Want: Unlocking the Science of Personality Change by Christian Jarrett (Robinson). Transcend: The New Science of Self-Actualization by Scott Barry Kaufman (Tarcherperigee). Metamorphosis: How and Why We Change by Polly Morland (Profile).