If you're like most of the 111 million people who watched the Super Bowl this year, you probably had a nice belly laugh seeing Jerry Seinfeld reunite with the Soup Nazi in that Acura commercial, but chances are you didn't run out to the Acura dealership afterward. Now, a new study by the media analytics company Ace Metrix is revealing why funny commercials are not as effective as their prevalence would suggest.

Ace Metrix looked at every national commercial released from January 2011 through March 2012, a total of more than 6,500 ads, to measure the effectiveness of humor in advertising. Using its own self-devised Humor Index, the company gauged such criteria as likability, watchability and level of persuasion -- all of which were based on open-ended responses from online surveys.

What it found was that funny commercials were often seen by respondents as more appealing and more memorable than their unfunny counterparts, but those same commercials were less likely to increase desire or intent to purchase than commercials that played it straight. In other words, funny ads are useful for entertaining viewers, but are not the most effective way for advertisers to convince those viewers to buy the product.

"Messages must be built of substance and should use humor as a supplement -- not a replacement -- to create the most effective ads," wrote Michael Curran, Ace Metrix's director of insights and analytics and the study's author. "Funny ads drive other great advertising attributes such as attention and likeability. However, low information and relevance on many funny ads results in creating lower desire for the advertised products than non-funny ads."

Nevertheless, advertising agencies have long relied on humor as a means of creating a strong connection between products and consumers. Steve Bassett, a creative director at the Martin Agency, said the perception within the industry is that humor works, at least when it's used appropriately. "Humor has always been very successful for us," he said.

Bassett should know. As the agency's senior vice president, he's been one of the guiding forces behind the famously wacky advertising ethos of one of its top clients: GEICO car insurance, where a snarky computer-animated gecko has served as the company mascot for more than a decade. In that time, GEICO has gone from being the seventh-largest car insurer in the country to being the third. Bassett credits some of that success to the simple fact that, when it's time to buy car insurance, GEICO's humorous ads are fresh on the minds of customers.

"People actually look forward to our commercials," he said. They talk about them. "That kind of brand awareness is very important for car insurance, because it's not something people buy every day."

GEICO stands out as a kind of funny-ad pioneer in its industry. The Martin Agency first developed the GEICO Gecko character in 2000, when a Screen Actors Guild strike prohibited actors from working in commercials. Since then, rivals like Progressive and Allstate have followed suit with their own amusing campaigns. But while GEICO may make humor appear so easy a caveman could do it, Ace Metrix suggests that, in terms of informing potential customers about a product or service, being funny is not enough.

In his research, Curran notes that humorous ads tend to be light on informative content, which in turn creates a lower desire for the advertised product. However, he goes on to say that humor can be an extremely effective tool when placed in a context relevant to the product -- for instance, a cute baby gag in a commercial for diapers. "The funniest ad in our study, 'Baby Wets the Room' from Huggies, has broad relevance to many people," Curran wrote. "Conversely, a funny ad on a fictional space ship, while funny, does not deliver the effectiveness of a highly relatable ad."

Some of the most memorable humorous campaigns seem to align with Curran's results. Apple's Effie Award-winning Get a Mac commercials -- which featured a young and hip Mac in personified form and pitted him against a pudgy, blundering, middle-aged PC -- used humor to convey a clear message that Macs were the superior choice for savvy consumers. By that same standard, however, many of GEICO's most successful spots -- which feature funny characters but not a hint of the product -- fly in the face of Curran's wisdom.

Of all the commercials Curran studied, about 20 percent used humor, a statistic that speaks volumes about advertisers' perceptions toward the effectiveness of humor. But even if his conclusions don't tell the whole story, advertisers might still want to think twice before putting the method in front of the message. Nowhere is this lesson more obvious than in GEICO's indelible promise that 15 seconds could save you 15 percent or more on car insurance. It's not exactly a gut-buster, but it's still a nice incentive.

"We've had the same tag statement for 18 years," Bassett added. "I think that says something about what works."

The Top 10 Funniest Brands
(Ranked by Ace Metrix's Funny Index)

1. Doritos: 635
2. Clorox: 585
3. eBay: 501
4. Farmers: 531
5. Slim Jim: 452
6. Aflac: 442
7. New Era Caps: 421
8. Miller Lite: 420
9. GEICO: 401
10. Bounce: 365