We should rethink the long sentences handed down to young people who commit crimes, as research shows their decision-making faculties are still developing

As a teenager I got into a fight that frightened me so much I've avoided them ever since. What scared me was the coldness that went through me as we were tearing strips off each other. I shut down emotionally. I wanted to kill the boy whose throat I had my hands round. There was no interest in the consequences, my rage was blind to it. It was the brute force of a heavy-set PE teacher, prising us apart that stopped me doing something I would have regretted for the rest of my life.

I work in a young offender prison in the south-west. The crimes of the young men I mentor through my writing programme range from theft to murder. During my last visit on the young lifer's wing, I was struck by the childlike nature of one teenager I was running a one-to-one with. On the landing he had the swagger and confidence of a grown man and many of the other prisoners gave him a wide berth. It was clear he was intelligent and had already been involved in way too much horror for his 17 years on the planet. He was streetsmart and tough. But he was also in many ways still a child. In the safety of that room he could, consciously or not, let his guard down and reveal more of who he really was: vulnerable, damaged, frightened and confused. This I could identify with from my own teenage years.

Another young prisoner who had murdered a man, told me he knew exactly what he was doing, he wasn't drunk or stoned and had given his act of fatal violence careful premeditated thought. He was 14 years old when he committed the crime and had been sentenced to a minimum of nine years. I didn't believe he really knew or fully understood what he was doing. I had a conversation with a professional within the prison about my concern around the heavy sentencing of these young men, sentences equivalent to those of an adult, and got a curt response. I was told I didn't understand the true nature of these young men and that they were fully responsible for their actions. They knew what they were doing.

A recent report from the Royal Society based on research into the neuroscience of the development of the teenage brain presents clear evidence that key factors around decision making and impulse control are not fully formed until the age of 20 and that teenage brain development varies a great deal from person and is heavily dependent on a mix of upbringing, education, environment, and peer relationships.

The sentencing handed down to many young people does not always take into account the many factors that make up the decision-making mind of a teenager. Some of these young people need to be in prison, for the public's safety and their own but the majority do not. I challenge the government and the judicial system to take into account the complexities of brain function and growth in young people and the wide range of factors that lead to the crimes being committed. Sure, it would be easy to stick to the current template of sentencing: one size fits all, save time, let the public believe that the government is in control. It isn't.

So the next time you hear of a young person sentenced to more years in prison than they have been on the planet, remember your own time as a teenager and how you dealt with conflict and decision making. Spare a thought for the possible circumstances that have led to the crime you hear being committed. Above all, remember that a crime carried out by a 14-year-old is very different to that committed by a 24-year-old and needs to be treated and approached with a greater understanding of the developing mind.

? Caspar Walsh is an author and journalist and founder of the award-winning charity Write to Freedom.