Many people buy a car (probably their single biggest discretionary purchase) based on slamming a door, kicking a tire and judging the handshake of a salesperson.

We choose a surgeon based on the carpeting in his office and a politician by his hair cut.

During the first week of swine flu vaccines in New York, most parents (more than half!) chose to keep their kids out of the program.

Interviewed parents said things like, "I'm not sure it's safe," and "I wanted to see if it affected other kids…"

No mention of longitudinal studies or long-term side effects. No science at all, really, just rumors and hunches and gut instincts.

This gut-instinct approach served people well for hundreds of thousands of years, but it's pretty clear that it doesn't work in a complex world. Eating salmon at a wedding feels 'safe' because we always have, but of course any professional scientist will tell you that farmed salmon is an ecological disaster. You can't see the problem, so you ignore it.

Audiophiles spend thousands of dollars rewiring the electrical lines in their house with .99999% pure copper, ignoring the fact that the power from the street is in the same old cables. Adding decimal points to our irrationality doesn't change much.

The problem with being an amateur scientist is precisely the reason that marketers relish the opportunity to sell to us, the amateurs: we make stupid decisions, easily manipulated by those who might choose to do the manipulation (on their behalf or on ours).

The news here is not that people are irrational, giving too much credence to the dramatic and the local and the short-term (that's not news), but that people have added a veneer of scientific rationality to their irrational decisions. Armed with Zagats or internet data or some rumor off Snopes, we act as though now we're supremely rational choicemakers.

This is one of the problems with breast cancer screening. It appears to give information, really good information, but in practice, it doesn't. Since the information is vivid, we give it too much credence.

The challenge for people trying to market vaccines or highlight long-term side effects of various consumer choices is that it's much easier to spread a story about exploding cars or hair falling out than it is to spread a story of 'nothing bad happens' or 'no one got the swine flu and died' or 'three years from now, this section of ocean will be dead.' We prefer the vivid anecdote to the dry and statistically useful fact, which in a complex world, is to our detriment.

PS if I was marketing the swine flu vaccine, I'd name it after a kid who died last season and put her picture on the release form. Alas, teaching amateurs like us to be real scientists is going to take a while.