Didn’t get an iPad over the holidays? You may be one of the one in five Americans aged 18 to 34 who plan to buy one in the next six months.

That’s according to a study by Vision Critical that found interest in the iPad among younger adults has increased since March 2010. Why the increased interest, you ask? It’s not necessarily that everybody else you know already has one. Researchers say the FaceTime video calling application, rumored to be included in the 2011 generation iPad, has a lot to do with it. More than one-third of Americans aged 18-24, or 37 percent, find the idea of having the FaceTime application on an iPad “extremely” or “very” appealing, suggesting the ability to make video calls with the iPad could expand the tablet’s potential customer base even more.

Interestingly, Americans continue to view the tablet as similar to a range of other digital devices, such as desktop/laptop PCs, smartphones, netbooks and wireless eReaders. But Vision Critical says the proportion of consumers who find the iPad similar to many of these other devices has dropped, leading to the idea that consumers are increasingly considering the iPad and other tablets as a new, distinctive product category. 

“The decreased association of the iPad with a wide range of devices suggests that in less than a year, the iPad has been successful at both creating and leading the new category of multimedia tablets,” said Matt Kleinschmit, Vision Critical’s senior vice president of Media, in a press release. “What is perhaps more interesting, however, is that there was no drop in how consumers perceive the iPad relative to desktop/laptop PCs and wireless e-readers. This is a clear sign that after months of learning more about the type of content, applications and usage scenarios available for the iPad, consumers perceive these devices as increasingly interchangeable – which could lead to cannibalization of sales for laptops and e-readers in the near future.”

Cannibalization, you say? Apple executives had something to say about that in an earnings conference call last year. Asked about cannibalization during the third-quarter call back in July, COO Tim Cook pointed out that Apple reported its best Mac quarter ever in the same quarter that iPad sold almost 3.3 million units. Some analysts suggested a reverse halo effect, where people who buy the iPad later decide to pick up some other Apple device. Cook pointed out that if it turns out that the iPad cannibalizes PCs, that’s great for Apple because Mac still has a small market share and there are a lot of PCs out there to cannibalize.

It may be a couple more weeks before we hear from the horse’s mouth just how many iPads sold over the holidays. Apple plans to discuss its first fiscal quarter results on Tuesday, Jan. 18.

Vision Critical’s survey was conducted online Nov. 26 to Nov. 28 among 1,003 American adults who are Springboard America panelists. The margin of error is +/- 3.1 percent.