There is a metric you won’t find anyone measuring but it may very well be the most important metric your brand needs to monitor. That’s the types of impressions you make. I don’t mean “number of impressions” as in advertisements served or pages viewed. I mean “how many different ways do you make a first impression?”

Photographer Peter D’Aprix shared a fascinating and compelling overview of how pictures help Web sites in many tangible and intangible ways on the esteemed LED Digest today. In a previous post I had written: “The impression you make on the Web can be just as polarizing as the impression you make in person. Everything that goes into your Web site presentation determines who will stay and who will leave your site immediately. That includes the pictures you provide of yourself.”

We were talking about whether pictures on Web sites improve conversion rates (the short answer is that they can). I introduced the concept of establishing credibility, but I wanted to stress the importance of understanding who was visiting your Web site. A brand may be relevant to several audiences but it has to market itself differently to those audiences. Advertisers have understood as much for years but in Web marketing the facts and opinions are clouded by limited points of view.

Search engine optimizers often advise clients not to create multiple Web sites for their products and services, and they cite studies, anecdotes, and opinions about the detrimental effects of “splitting your PageRank”, “confusing the search engines,” “sending mixed messages,” etc. Traditional marketers and business people often respond by saying, “It makes sense for the business to use multiple Web sites.”

Indeed it does. If your markets are divided between kids and adults, white-collar professionals and blue-collar skilled laborers, between genders, nationalities, and language groups - in short, if your markets are distinguished from each other by clear barriers you cannot ignore, then you need to send different messages to those markets.

The confusion in Web marketing arises from how to shape the messages. An entirely different theme may be required, but some companies make the mistake of replicating a theme across multiple Web sites. They want to bind the network together with a super corporate style, and in doing so they say to their markets that “your priorities and interests are not reflected in our priorities and interests.”

You can market the same book to over-50 customers and under-20 customers effectively by speaking to them in their own words and earning their trust and credulity by presenting your message in terms they are comfortable with and understand. On the Web that often means designing more than one site where each site has its own look and feel. You can make the corporate connection through linkage and referral pages.

The challenge, of course, is to maintain the corporate brand - you don’t want to sacrifice the identity you have created for your company because there is significant value in that identity. But you want to build rapport with your audience and target the right market with the right content and presentation.

In his LED post, Peter D’Aprix wrote: “the eye sees the collection of ALL the constituent parts of a page as a whole collection of the parts first, then drills down to those parts that attract the viewer. The way the parts are organized and thus interact can make a huge impact on the viewer either positively or negatively. One can enhance the other. Depending on what parts attracts the viewer based on their preferences, that is where they will go in order of their personal preference.”

Emphasis is mine, but I agree whole-heartedly with his point.

You have to build the message in the same visual language your audience understands, and not just in the idiomatic structures they use. Idiom changes over time but first impressions last forever. People who become closely associated with a brand remember that first experience vividly. Their brand loyalty may be altered by poor quality or service but they’ll always remember that first moment they felt interest in the brand itself.

How do you measure the quality of a first impression? It’s not easy to do on the Internet because people can come and go so quickly, or browse anonymously. They may clear their cookies, use dynamic IP addresses, or surf from friends’ computers. The same loyal customer may revisit your site many times and you’ll never know it, so when you evaluate the design of the site how will you know if the first impression factor has been reasonably assessed?

The impression we make when we enter a room is mirrored by the impression people make on us when we enter. With Web sites, visitors have more reliable metrics (their gut feelings) than Web site operators do. We don’t capture that moment when our visitors first appear. We don’t track success as easily as we capture transactions.

Brand loyalty is neither a transaction nor even a sequence of transaction. It’s an intangible quality that comes into life in an instant, gathers strength over time, and ultimately fades or dies. We build entire relationships through brand quality and value. But we begin those relationships in the briefest of moments, the first moments when we present ourselves to our new partners and customers.

If you’re managing a multi-audience marketing campaign, one Web site may not provide optimal results for you.