Sense of time

Although the sense of time is not associated with a specific sensory system, the work of psychologists and neuroscientists indicates that our brains do have a system governing the perception of time. This is a highly distributed system including the cerebral cortex, cerebellum and basal ganglia as its components. One particular component, the suprachiasmatic nucleus, is responsible for the circadian (or daily) rhythm, while other cell clusters appear to be capable of shorter-range timekeeping. The sense of time is impaired in some patients with neurological diseases such as Parkinson's Disease and Attention Deficit Disorder.

Psychoactive drugs can also impair a person's perception of time, as those on stimulants tend to underestimate time intervals, whereas those on depressants tend to overestimate them. Those lack of proper estimations are generally attributed to the idea that the more neurotransmitters active in our brain, determines the ratio to which our conscious and sub-conscious selves can perceive perception in relation to time. Neurotransmitters such as dopamine and adrenaline are also thought to be partly responsible for one's perception of time.

Imagine you are travelling in a car, without a speedometer, at a speed of 100km/h. You then pass a road sign telling you the speed limit is now 50km/h. You will find that without the aid of the speedometer you will slow to a speed of around 70km/h. This phenomenon is due to the mind's ability to alter conscious perception, much in the way that when you watch the ending credits of a movie and then redirect your vision elsewhere, your vision appears to roll in the reverse direction of that in which the credits were moving. This is a function of the brain believed to be used for the maintenance of a perceived balance adapted to our environment. Without this mechanism, we would be unable to attune to our current environment with its day-long and year-long cycles.

Steven Hawking's book, 'A Brief History Of Time', touches briefly on the subject. Hawking suggests that the perception of time is a ratio; Unit of Time : Time Lived. For example, one hour to a six month would be aprroximately "1:4032", while one hour to a 40-year-old person would be "1:349,440" Obviously, an hour is much longer to a young child, or infant than to an aged adult, even though it is the exact same amount of "Time".