Albert Einstein taught us that time is relative in a physical sense, but personal experiences teach us that time is also perceptually relative.
As evidenced by dental appointments, traffic jams, or enigmatic bouts of explosive diarrhea (not mutually exclusive, unfortunately), our perception of time is constantly changing based on external and internal factors.
Furthermore, the fundamental nature of time remains a conceptual conundrum.
Physicists and experimental psychologists have proposed various definitions of time, including a thermodynamic view of ever-increasing entropy, or a self-ordering series of quantum effects.
Psycho-physiologically, the human sense of time may rely on pulsating internal ‘clocks,’ such as neuronal oscillations. Alternatively, the brain may base time on a weighted sum of current perception and past experience.
So, in a unique, recent study, human sciences researchers Achille Pasqualotto and Hiroto Kawarada from the University of Tsukuba in Japan conducted a sensory substitution experiment and used a computational model to explore how auditory stimuli (sounds) can alter participants’ perception of time.
“This study investigated the effect of background moving sounds on the estimation of time durations, and we discovered that an approaching background sound significantly accelerated the perceived time when compared to a receding sound,” the researchers write in their paper.
In the experiment, the scientists split 48 blindfolded participants, aged 22 years on average, into three groups, each assigned to a different auditory test.
Equipped with headphones, one group heard background sounds that seemed to be approaching them. Another group heard background sounds that seemed to be receding. The third group, the control group, heard scrambled background sounds.
The researchers subjected all three groups to an additional, foreground sound, a short-duration sine-wave tone, meaning it was clear and markedly distinct from the background sounds.
Immediately after hearing these foreground tones, the participants pressed and held down the spacebar for as long as they felt the foreground tones lasted, estimating their total duration.
The researchers then applied a computational model to analyze these experimental effects.
The experimental data and modeling results seem to generally agree, suggesting that approaching sounds lead to an overestimation of time.
In other words, when we hear something approaching us, it increases our alertness and arousal, therefore accelerating our sense of internal time – a process possibly facilitated by factors such as dopamine activity.
Receding sounds, conversely, seem to produce the opposite effect, leading to underestimations of duration.
“Our general explanation is supported by the studies on the detection of moving targets; they reported that detection is faster for targets closer to the observers, thus supporting the engagement of the attention,” the researchers explain.
“Additionally, we found evidence for the Vierordt effect, with a significant difference between estimations of shorter and longer time durations where the former are overestimated and the latter underestimated.”
Future research may focus on asking participants to ‘produce’ time: Instead of estimating the duration of a noise, they could be explicitly asked to hold down a button for several seconds, or other specified period of time.
The researchers also surmise that an approaching background noise that increases in tempo may produce an even more pronounced acceleration of internal time, as it would require more focused, immediate attention.
Related: Scientists Confirm Exercise Slows Down The Perception of Time
Yet overall, the results of this work appear to be in general accordance with previous temporal perception studies as well as theories like the scalar expectancy theory, which posits that animals and humans have internal clocks composed of three main components: an internal pulsating pacemaker that ‘ticks,’ our ongoing decision-making processes, and our memories.
The evolutionary explanation seems clear. Throughout the history of life, individuals who were able to react appropriately to approaching objects – be they a stalking leopard, visiting friend, or an oncoming automobile – exhibited a survival advantage.
And although we no longer face rampaging mammoths, our precise timing and subsequent motion prediction abilities still dictate daily life, whether we’re enjoying a leisurely game of catch at a cookout or piloting 4,000 pounds of steel through a busy intersection.
This research was published in Scientific Reports.
This article was fact-checked by Clare Watson and edited by Peter Dockrill. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
