When Chemists Attack

Kellie sent me a link to a study recently conducted at Clemson. It’s more likely that you’ll swerve out of your lane if you’re text messaging or messing with your iPod while you’re driving:

Text messaging and using iPods caused drivers to leave their lanes 10 percent more often in a simulated driving study conducted by researchers in the Clemson University psychology department.

[…]

Drivers who simply talked on cell phones were distracted and had slower reaction times but tended to stay in their own lane, however drivers who looked away from the road to use electronics were significantly more likely to leave their lane, said Johnell Brooks, assistant professor of psychology.

It’s not the results of the study that I want to hilight. The study, after all, tells us exactly what we expect: it’s not smart to text while driving. If you click the link above, you’ll see that the site describing the study allows comments. As I’m writing this post, the comments all say about the same thing. Here’s a sample:

And this is the college everyone raves about? Sounds like the only thing this place can do right is get drunk. What a waste of money. Ho[ne]stly I don’t think they should have even admitted they were doing this study because common sense would have given them the answer.

Commenters complained that the study was a waste of money and effort because the results confirm “common sense”. The problem with that argument is simply this: Common sense is commonly wrong. Because of this, it’s a good idea to actually test out things we think are “obvious”. You don’t have to dig very deeply in science to find a good example of common sense failing. Just consider fire.

When you burn a piece of wood, you get ash. The ash is lighter than the original wood. Common sense dictates that burning must be the loss of something within the wood.

During much of the eighteenth century, that something was called “phlogiston”, and the loss of phlogiston was obviously responsible for the difference in mass between wood and ash. Anything that burns must contain phlogiston, and that’s why ash is always lighter that the substance being burned.

We now know, however, that the sentence above is false. Burning doesn’t require the loss of anything. Instead, the burning process is the combination of a substance with oxygen from the air. How did we find that out? By actually testing the “common sense” idea!

More careful analysis of burning wood revealed that if you account for all of the gases given off, the gases and the ash together weigh more than the original wood.

It’s even more convincing to look at the burning of metals. No gases are released by the burning of metals like magnesium, so all you have to do to collect everything given off is to burn the magnesium in a container with a loose-fitting lid. It’s easy to show that the ash left behind weighs more than the original metal, and my intro chemistry students do this in lab.

The weight gain was eventually discovered by Lavosier to be due to oxygen.

So, don’t laugh too hard when some scientist seems to be testing something that’s “common sense”. It’s true that common sense isn’t very common, but it’s also true that common sense isn’t always … sense!