Who cares? 148.7 people, apparently.

That’s what Robin Dunbar, director of the Institute of Cognitive and Evolutionary Anthropology of the University of Oxford, calculated as the cognitive limit of the number of people with whom we can hold meaningful friendships.

Dunbar’s Number has ramifications in social media, sure, but for small business, it has far more to do with marketing and influence and the importance of delivering a delightful customer experience and echoing that experience and your company’s values in your messaging.

I know this because, long before I’d heard of Dunbar’s Number, Roy H. Williams once again intuitively uncovered a profound truth that science would later prove.

Around the turn of the century, Roy first wrote about a “realm of association” in his best-selling Wizard of Ads trilogy. On January 23, 2012, he summarized it thusly in his Monday Morning Memo, “Who Is Your Customer?”

Decisions are rarely made in a vacuum. Each of us is guided by co-workers and family members, neighbors and friends.

If you are normal and healthy, you maintain about 250 people in your “realm of association.” Some of these are permanent members of that realm while others will pass through your life and be replaced. But the number hovers at about 250. And guess what? Beyond their connection to you, these 250 people have little, if anything, in common. They are your personal world: the male and female, young and old, rich and poor, white-collar and blue-collar “masses” that give your life purpose and meaning.

You are someone’s target customer. If I fail to reach you with my ads but my company is beloved by half the people in your realm of association, what’s the likelihood that you’ll hear about me?

Google and Facebook, radio and television, magazines and mailers, billboards and flyers are called mass media because they reach the masses. The ability to “target” using mass media is more illusion than fact.

I’m here today to tell you to deliver a powerful experience and echo that experience and your company’s values in your message campaigns.

Roy used to say it was 250 – which always sounded logical, even after Facebook friends lists started growing into the high three or four digits.

Turns out Roy was close. Scary close.

And if your company can get me to share my experience, there’s a good chance I’m going to affect the worldview of about 150 people.

So, why not make my experience an amazing one? Because once you start multiplying each of today’s customers by 150, you start to see the possibilities of science working in your favor.