Big name marketers from soft drink makers to cars to packaged goods are shifting greater shares of their marketing budgets online. But a report from Dynamic Logic indicates that, over the last two consecutive years, those ad dollars are having less of an impact, ClickZ reported. Among the reasons for this paradox: too much clutter, which has led to a growing indifference to display ads. The report’s specific findings showed:

—The “brand message association” experienced by users who saw an online campaign between Q404 and Q305 was 4.3 percent higher on average than a control group. But that number slumped for the next two years to 3.5 percent and 2.5 percent, for 2006 and 2007, respectively.

—Brand awareness also suffered during that same period, as online ads drove recognition up 3 percent in 2005. After that, interactive ads contributed only 2.2 percent to brand awareness.

—Online ad awareness is a category that rose significantly in 2005, only to retreat shortly after. That measurement came in 7.3 percent in 2005, then fell to 6.4 percent the next year while finally resting at 4.8 percent in 2007. Still, some other numbers were more mixed. Internet ads lifted “purchase intent” have been largely unchanged the past two years. That metric was 1.3 percent in 2007, down only slightly from 2005’s 1.6 percent. And “brand favorability” tipped upward in 2006 to 1.9 percent from 1.8 percent the year before; however, in 2007, it was 1.4 percent.

Despite the negative trend, neither the changes nor the numbers themselves seem particularly great. ClickZ also cited a few suggestions for how to reverse the downward direction of online ads’ branding impact:

—Less display, more social: Web publishers should lower the amount of ads per page, while marketers should minimize their reliance on traditional ad forms like display in favor of doing more viral and social marketing, advises Sarah Fay, CEO of Carat and Isobar USA.

—Finding the metrics: Dynamic Logic expects marketers to follow Fay’s advice. But at the moment, the metrics aren’t there. Ken Mallon, Dynamic Logic’s VP Product Development and Custom Solutions:  “The tricky part is getting your control group. How do you intercept people before they get exposed to it? But we have ways.”