Ah, the languorous days of endless summer! Who among us doesn’t remember those days and wonder wistfully where they’ve gone? Why does time seem to speed up as we age? Even the summer solstice–the longest, sunniest day of the year–seems to have passed in a flash.

No less than the great William James opined on the matter, thinking that the apparent speed of time’s passage was a result of adults’ experiencing fewer memorable events:

“Each passing year converts some of this experience into automatic routine which we hardly note at all, the days and the weeks smooth themselves out in recollection to contentless units, and the years grow hollow and collapse.”

Don’t despair. I am happy to tell you that the apparent velocity of time is a big fat cognitive illusion and happy to say there may be a way to slow the velocity of our later lives.

Although the sense that we perceive time as accelerating as we age is very common, it is hard to prove experimentally. In one of the largest studies to date, Dr. Marc Wittmann of the Institute for Frontier Areas of Psychology and Mental Health, in Germany, interviewed 499 German and Austrian subjects ranging in age from 14 to 94 years; he asked each subject how quickly time seemed to pass during the previous week, month, year and decade. Surprisingly, there were few differences related to age. With one exception: when researchers asked the subjects about the 10-year interval, older subjects were far more likely than the younger subjects to report that the last decade had passed quickly.

Other, non-age-related factors influence our perception of time. Recent research shows that emotions affect our perception of time. For example, Dr. Sylvie Droit-Volet, a psychology professor at Blaise Pascal University, in France, manipulated subjects’ emotional state by showing them movies that excited fear or sadness and then asked them to estimate the duration of the visual stimulus. She found that time appears to pass more slowly when we are afraid.

Attention and memory play a part in our perception of time. To accurately gauge the passage of time required to accomplish a given task, you have to be able to focus and remember a sequence of information. That’s partly why someone with attention-deficit hyperactivity disorder has trouble judging time intervals and grows impatient with what seems like the slow passage of time.

The neurotransmitter dopamine is critically important to our ability to process time. Stimulants like Ritalin and Adderall, which increase dopamine function in the brain, have the effect of speeding up time perception; antipsychotic drugs, which block dopamine receptors, have the opposite effect.

On the whole, most of us perceive short intervals of time similarly, regardless of age. Why, then, do older people look back at long stretches of their lives and feel it’s a race to the finish?

Here’s a possible answer: think about what it’s like when you learn something for the first time–for example how, when you are young, you learn to ride a bike or navigate your way home from school. It takes time to learn new tasks and to encode them in your memory. And when you are learning about the world for the first time, you are forming a fairly steady stream of new memories of events, places and people.

When, as an adult, you look back at your childhood experiences, they appear to unfold in slow motion probably because the sheer number of them gives you the impression that they must have taken forever to acquire. So when you recall the summer vacation when you first learned to swim or row a boat, it feels endless.

But this is merely an illusion, the way adults understand the past when they look through the telescope of lost time. This, though, is not an illusion: almost all of us faced far steeper learning curves when we were young. Most adults do not explore and learn about the world the way they did when they were young; adult life lacks the constant discovery and endless novelty of childhood.

Studies have shown that the greater the cognitive demands of a task, the longer its duration is perceived to be. Dr. David Eagleman at Baylor College of Medicine found that repeated stimuli appear briefer in duration than novel stimuli of equal duration. Is it possible that learning new things might slow down our internal sense of time?

The question and the possibility it presents put me in mind of my father, who died a few years ago at age 86. An engineer by training, he read constantly after he retired. His range was enormous; he read about everything from astronomy to natural history, travel and gardening. I remember once discovering dozens of magazines and journals in the house and was convinced that my parents had become the victims of a mail-order scam.

Thinking I’d help with the clutter, I began to bundle up the magazines for recycling when my father angrily confronted me, demanding to know what the hell I was doing. “I read all of these,” he said.

And then it dawned on me. I cannot recall his ever having remarked on how fast or slow his life seemed to be going. He was constantly learning, always alive to new ideas and experience. Maybe that’s why he never seemed to notice that time was passing.

So what, you might say, if we have an illusion about time speeding up? But it matters, I think, because the distortion signals that we might squeeze more out of life.

It’s simple: if you want time to slow down, become a student again. Learn something that requires sustained effort; do something novel. Put down the thriller when you’re sitting on the beach and break out a book on evolutionary theory or Spanish for beginners or a how-to book on something you’ve always wanted to do. Take a new route to work; vacation at an unknown spot. And take your sweet time about it.