Friday, June 22, 2012

How many times a day do you move your head?

Every day that I travel to work, I drive about 2 miles through a city. In parts of the drive, I have to stop at every street and look to make sure that no traffic is proceeding or pedestrians crossing. Thus, I have to look back and forth several times before cautiously proceeding.

When traffic is heavy, I may have to wait a minute or two before the coast is clear. It is then that I have thought to myself:

How many times a day do I move my head?

Silly as this thought is, I've marveled at the durability and reliance of the human body.  Whether we are walking, talking to someone, eating, driving, playing a sport, getting dressed or whatever, we are continually moving our heads.

We move our head constantly, and, it never breaks.

To answer my question, I decided to estimate how many times a day I (and others I guess) move my head. At first, I thought that it is moved about once each second while we are awake. To confirm this, I went outside and sampled my theory using 2 rules. First, I defined moving the head as moving its position from one spot to another (up, center, down, left, right, nodded, etc). Second, I used a stopwatch to time folks involved in various activities.

Surprisingly, I found that most people move their head once every 2.5 to 3 seconds on the average. The head is moved more rapidly when people are talking to each other and crossing the street. But, it is moved less frequently when reading or looking at a computer terminal.  After several hours of watching, I compiled my notes and averaged the head movements. It is then that I discovered the 2.5 to 3 second interval.

Knowing this, I was able to estimate that people move their heads:
• 20-24 times a minute
• 1,200 - 1,400 times an hour
• 14,400 - 17,208 in twelve hours
• 28,800 - 34,416 times in a day. (that's my answer)
• 10,512,000 - 12,614,400 per year.
We take certain mobility functions like this for granted. But just think, what a marvel the human body is. As our heads move about 25,000 times a day, our arms, legs, eyes, and fingers are also moving. All at the same time. And even with all this simple movement, the muscles responsible for these functions rarely break and keep working!