As a child, summer seemed eternally long to us – not anymore today. Why it is

Time is relative – apart from Einstein’s theory of relativity, we are all aware of this in everyday life. When we are waiting for someone, minutes seem like hours, but conversely, when we are busy, hours seem like minutes.

Many of us are also familiar with the strange plasticity of the perception of time when we remember the summers of childhood: then they were almost endless – while today they are over as soon as they started.

Scientists from the Eötvös Loránd University in Budapest got to the bottom of this phenomenon. They investigated whether the perception of time changes with age – and if so, how and why we perceive the passage of time differently. They published the results of their research in Scientific Reports.

The researchers, led by Zoltán Nádasdy, examined the degree of eventuality – to put it bluntly: how much happens in a given period – and its effects on the perception of time.

Study participants were divided into three age categories: 4 and 5 years, 9 and 10 years, and 18 years and older. Everyone then saw two films of exactly one minute each. Both videos contained excerpts from a popular animated series that were similar in their visual and audio characteristics – except for the eventfulness aspect, i.e. how much happened.

One video showed a rapid sequence of events (a police officer rescues animals and arrests a thief), while the other showed a monotonous and repetitive sequence (six prisoners escape in a rowboat). Both films were shown to the subjects in rapid succession, with one half seeing the exciting clip first and the other half seeing the boring one.

Then the study participants only had to answer two simple questions: “Which video lasted longer?” And, “With your arms outstretched, can you show how long the video was?” Even a four year old can understand such simple questions.

What was interesting was the different behavior of the subjects when they used their arms to indicate the duration of the videos: Although there were no instructions for the arms to be stretched horizontally, more than 90 percent of the adults did just this. In the children, on the other hand, only about half made a horizontal movement, while the others displayed the duration vertically.

However, the researchers did not expect which video was classified as longer by which group: More than two-thirds of the subjects from the youngest group described the exciting video as the longer, while three-quarters of the adult study participants rated it as the longer boring video.

The middle group of 9 and 10 year olds rated the length of the videos largely comparable to the adult group, albeit slightly less. Including this age group, the tipping point between the two conflicting views was around seven years old.

Why this different assessment of duration? The scientists point out that the assessment of duration differs from the assessment of geometric length, for example. Our senses do not perceive duration in the same way as brightness, loudness, or length. When we see two lines next to each other, we immediately see the difference in length.

We can directly compare the duration of two events if they happen simultaneously before our eyes. The only way we can compare successive events in terms of duration is through memory, and that can be tricky.

Since our brain has neither a reliable central clock nor a direct sensory representation of duration, we must resort to a heuristic to estimate duration. Heuristics are strategies we use when we are uncertain and have limited information. Then we apply a surrogate rule that doesn’t exactly match what we’re looking for, but can still give us a result that helps us make a decision quickly and efficiently.

A possible substitute for “expensive” could be something concrete related to the content of time: “What can I tell more about?”, a representativeness heuristic. The moving video had more action to report on, while the low-event video could practically only be summed up with the term “rowing.” Based on a representativeness heuristic, children in the age group 4 to 5 years experience the moving video as longer.

However, if this notion of duration is a good alternative to “time”, why change it later? For the scientists, this is because around the age of 7 years there is a switch to another heuristic, namely the sampling heuristic. This consists of checking the flow of time by sensing it in a certain way – for example, by looking at the clock or looking out the window and observing the flow of traffic. The more often we do this, the more reliable our estimate is.

The sampling heuristic is based on another concept of time that we don’t learn until we are between six and ten years old: that of absolute, universal time. We use it when we make appointments or consult a schedule. We are aware that time is independent of the observer, but can go faster or slower in our subjective experience. We can reduce the subjective component by controlling the passage of time.

However, our brain is not always able to tell the time. When another task demands attention, the brain may skip a few cycles when sampling absolute time. On the other hand, when we wait for someone to be late for an appointment, the brain counts the seconds and time slows down.

This also plays a role when we watch a movie. When it excites us, the quick succession of actions leaves us no time to think about anything else, like a job or a to-do list. Instead, the mind is completely absorbed in the fictional reality of the film’s plot. However, if the movie is boring, look at the clock or think about where you could be at that moment. All these distractions from film allow us to better understand the absolute flow of time.

These two different heuristics, which govern our perception of time before and after the age of about seven years, explain why summer seemed so long in childhood, but is now so over. After this change, boring sessions seem longer than they really are, and this will accompany us throughout our lives.