Everyone has experienced sitting at a restaurant and wondering why their food is taking so long. That familiar red stoplight always seems determined to make you late for school or work. It only takes an extra moment of delay to makes us antsy and impatient. How do we differentiate between a moment too soon and a moment too long?

One study conducted at Manchester University discusses the pacemaker-accumulator mental time-keeping model as a possible explanation.1 In this model, there are three “stops” that timing information has to go through for you to determine how long something is taking: the pacemaker, the accumulator, and the reference memory.1 The pacemaker creates a neural representation of how many “time ticks” it takes to complete a task, which are counted by the accumulator.1 The number of “time ticks” stored in the accumulator are then compared to the number of “time ticks” in the reference memory, which is a record of the average time the task has taken in the past.1  If the number of “time ticks” in the accumulator is significantly different from that stored in the reference memory, our brain know something’s wrong.1

However, our pacemaker doesn’t always tick at the same rate. The variability in our pacemaker also alters our time perception in stressful situations to increase our chances of survival. In a recent study, subjects who jumped backwards off a 15-story building were able to read rapidly changing numbers during their free-fall that they could not read while safe on the ground, suggesting that our perception of time slows down when we are reacting to high risk situations.2

Timing is also related to our state of arousal and attention, which is dependent on dopamine levels in our brain.3 When you feel like you haven’t eaten for hours, your arousal increases the amount of dopamine in your system and therefore the speed of mental processing, making the outside world feel like it’s moving in slow motion. When you are partying with your friends, your body is too busy attending to the good vibes to pay attention to your pacemaker, and hours fly by like seconds.

So next time you’re falling asleep in your never-ending physics class, try paying attention and it will be over in no time!

Natasha Mehta is a sophomore from Hanszen College at Rice University.


1. McGrew, K. Introduction to pacemaker-accumulator mental time-keeping model. http://www.brainclock.net/2006/10/introduction-to-pacemaker-accumulator.html (accessed 02/23/16), part of BrainClock.

2. Kotler, S. When Life Flashes Before Your Eyes: A 15-Story Drop to Study the Brain’s Internal Timewarp. http://www.popsci.com/science/article/2010-03/how-time-flies (accessed 03/11/16), part of Popular Science.

3. Falk, D. Do Humans Have a Biological Stopwatch? http://www.smithsonianmag.com/science-nature/do-humans-have-a-biological-stopwatch-164710819/?no-ist (accessed 02/23/16), part of Smithsonian.