Ever wonder why your childhood unfolded so unhurriedly, but your 30s passed on a light rail?

Time perception is a construction of the brain. How fast we perceive time to be passing – or “mind time” – can be manipulated or distorted. Evaluations of time differ based on our state of being at the time of judgment. If you’re bored or suffering, every second counts, and time seems to expand or slow down. When you’re ecstatic, moments glitter right through your fingers.

Mind time also depends on your projected future state of being. If you’re counting down to a root canal, time speeds up as you wait. But if you’re tallying days until the birth of your first child, time seems immeasurably slow.

What would happen to our sense of time if we knew we could to live to be 150? Or even 500?

Proponents of “radical longevity” believe that the first person to live beyond 150 years is already born. Billionaire futurists like Peter Diamandis are helping to develop gene sequencing techniques to make 100 the new 60. Other pioneers like Aubrey de Grey believe longevity research will enable “longevity escape velocity,” a point when our technological ability to add years to our lives catches up to passing time until we not only break even but defeat aging altogether.

Having more time sounds divine. But critics fear that longer lifespans will rob us of the urgency that lends life meaning and value and will motivate us to procrastinate more.

Is this true?

Scientists, including Dr. Joseph Ferrari, distinguish between regular procrastinators and chronic procrastinators whose problems relate to emotional regulation, not just time management. Most of us are merely situational procrastinators, depending on the perceived nature of the task (e.g. its “utility”) combined with mood (e.g. pessimism/optimism) and personality attributes like self-discipline and impulsivity.

Given how many factors must align to impact the average person’s propensity to manage one’s time, it seems unlikely that living longer will change our existing habits on a wider scale.

Still, will living longer feel like longer?

One theory contends that time speeds up as we get older if we consider the proportionality of time perception related to age. The older you get, the smaller one year is, as a percentage of your total life. So the years go by faster and faster. By the time you’re 98, a year is little more than one percent of your whole life and feels fleeting.

But if you add more years, it won’t fly as fast. As lifespans extend, one year of life at age 50 will feel longer for someone with a lifespan of 150 than 100. Time will slow down.

From a mathematical angle, this makes sense. However, critics argue that proportionality theory ignores the role of attention, emotion, and novelty, and that it doesn’t matter how long our lives are, but instead what we fill our lives with.

Cognitive psychologists like Martin Conway say that we are most likely to vividly remember experiences from between the ages of 15 and 25 – a time of firsts: Our first sexual relationships, first jobs, first travel without parents, first time living away from home.

The salience – or memorability – of these experiences is heightened by their novelty, forming a “reminiscence bump.” As we enter our 30s and novelty subsides, fewer memories stick with us over time.

This is important, because the fewer memories we have within a time period, the faster that time period seems to fly, according to cognitive psychologists. With fewer salient memories in our older years, time speeds up incrementally.

That is, unless we fill those years with rich, new experiences. That’s precisely what longevity research aims to do: to increase not only the number of years lived but to enhance our health and functionality so we live more fully for longer.

Longer lives will conceivably allow us to have two or three careers, two or three serial marriages or family lives, and so on. Though this scenario now seems improbable – even off-putting – it may eventually become the norm.

From infancy to old age, we accomplish psychosocial goals (e.g. formulating a sense of identity in adolescence; maintaining psychological and biological integrity, as well as legacy, in old age). Memory theorists say our specific memories are clustered around these “goal posts.” The more we have, the more we experience and remember, and the more time passes slowly, abundantly.

Maybe the sense of “urgency” isn’t what gives life meaning. Maybe a life with more time to create rich experiences and memories will be meaningful on its own, without the need to live in high-speed.

–By Kristin Kostick, Ph.D., research associate in the Center for Medical Ethics and Health Policy at Baylor College of Medicine