We’re an evolved species, and the genes of those who didn’t like sex aren’t around anymore.

For this reason, naked and scantily clad people are arousing. In my lab, we put electrodes on participants’ palms to measure activity in the eccrine sweat glands, or skin conductance.

The formula is simple. When you see a naked person — even if they’re not real — your body prepares for action. Your sympathetic nervous system activates, your palms begin to sweat below the surface of the skin, and you have a cascade of physiological responses associated with approach.

So it comes as no surprise that advertising drips with sexuality. They’re betting that sex gets your attention, and then you’ll pay attention to the messages and ideally associate positive feelings with the brand.

But does it work?

That’s a tricky question, you see. If you want to see academic research that shows sexy ads to be ineffective, I can provide it. If, however, you’d like to see some data that supports your decision to use sex in your ads, I can show you that, too.

I teach an entire class on sex and violence in the media, and we spend a lot of time trying to figure this out.

The confusion isn’t with the sex. The confusion is with the question that you ask.

You are, after all, a complicated human being and not an automaton.

Although I can tell you that part of your brain likes sex in ads, that does not tell the entire story.

The average man and the average woman have very different ideas about sex. If you look at the work of evolutionary psychologists, they’ll tell you good reasons for this.

For most of our evolutionary history, there were no courts or child support. Thus, for the average man, sex carried relatively little risk. Basically, the man was out a few hundred calories worth of biological material.

The story was different for a woman, however. An errant sexual encounter led to a 14-year commitment.

Thus from the perspective of gene propagation, women needed to be choosy and find a mate who was going to invest in the offspring. Resources were key.

Men, however, had a different strategy. Quantity was most advantageous. If 20 different women were left to raise your offspring alone, surely some of them would survive.

Now, I’ve read a lot of books on evolutionary psychology, but I wasn’t actually around on the Savannah. So I’m not sure these “just so” stories are true.

But they sure fit with our stereotypes of promiscuous, womanizing men. They also fit with the stereotypes of women being interested in a man’s time commitment, resources, and attention.

And apparently they do a good job explaining our responses to sex in advertising.

Women preferred a sexually explicit watch ad when the watch was wrapped in a bow and described as a gift, according to a study in an upcoming issue of The Journal of Consumer Research, according to The New York Times.

That gift business actually hampered men’s enjoyment of the otherwise sexual ads.

Nothing like the idea of commitment messing up some perfectly good sex, eh guys?

Man, we’re the weak half of the species.

Dismaying as the data are, I look forward to reading the actual study. Well-designed experiments such as these give proper credit to the complexity of human cognition and appeal to more mature disciplines, such as biology and psychology.

Sometimes sex works in an ad. Sometimes it fails. But it always compels attention. Your target market likely dictates whether that attention is good or bad.

If your target market is narrow, then you don’t have to worry about these individual differences. But in every case, you need to know.

Sex does sell. To some of the people, some of the time. And just because everyone is tuned to pay attention to sex doesn’t excuse marketers and advertisers from the hard work of knowing their consumers.

Photo Credit: iStockPhoto.com, 123foto.

That’s what the data say. Now I’m curious to know what you think about sex in advertising. What do you say?

Largely, this is lost on them. Sad, really.

Matching your brand to a small group of consumers may be the most important thing that you ever do.

My lab has done a lot of research of brand personalities, and to me the fascinating bit is just how easily people assign personalities to inanimate brands.

Right now I’m working on an exciting new project with Tim Laubacher. We’re using Darwin’s principles of natural selections to find out just what personality is attached to a given brand. More on this in coming months (read more on the underlying principles here).

What do targeting and personality have in common? Tailoring your target market. Sure, my last post blasted Burger King for too narrow a target, but most companies aren’t Burger King.

In the Dec. 8, 2008, Advertising Age, there is an article amazingly buried on page 4.

Under Jack Neff’s byline, “That 80% of sales comes from some 2% of buyers; Study: Package-goods brands’ consumers bases very small, yet diverse.”

Think about that. Two percent of all buyers make up the lion’s share of your sales.

Numbers like those start to make a strong case for broader use of customer-relationship management among package-goods players who’ve questioned its applicability because of the high cost per consumer.

This means that even the narrowest of traditional markets are likely to fail. This small yet diverse bit is tricky.

Tools such as the one that I am developing with Laubacher will allow real-time diagnostics of a brand’s multiple personalities. We can uncover these niche markets.

And then the real work actually begins. How do we reach these people when mass media will terribly overshoot and overspend. Then, how do we keep them among our 2%.

As Neff correctly identifies, relationships are the key. And compatible personalities are key to relationships. Think of this as a brand version of eHarmony: 29 dimensions of compatibility.

And you have to be careful not to drift. Once you establish your brand personality, you have to remain true to it. Google used to be one of my absolute favorite brands, but today I referred to them as the “Wal-Mart of the Web” due to their control of some of the features of this blog (Google owns Blogger).

I’m impressed with some corporate efforts on Twitter (e.g., @Starbucks). However, following 21,355 people (at present), this is more like a casual hook up than a committed relationship.

It’s a great time to study communications. I’m counting the days until the word “Mass” is toppled from the front of my college like a statue of Lenin or Hussein.