How much you spend this holiday season could depend on your age. At least, that’s one of the findings of a report from Briabe Media released yesterday. The marketing agency surveyed more than 12,000 respondents via mobile entertainment site MocoSpace.

The survey, conducted completely via mobile Web, indicates that consumer spending over the holidays will increase from last year for Americans under the age of 30 but decrease for 30-year-olds and above. And regardless of their spending, a lot of them will be using their mobile phones for comparison shopping even before they go into a store.

Fifty-nine percent of those under 19 plan to spend more and 52 percent of 20- to 29-year-olds plan to spend more, but the majority of 30- to 39-year-olds plan to spend less (53 percent). The survey finds a further drop-off after that, with 62 percent of 40- to 49-year-olds planning to spend less.

When it comes to mobile phone usage, 76 percent of respondents noted that their phone is “somewhat important” to “very important” to their holiday shopping this year. While 62 percent of respondents said they were likely to use their phone for product research before entering a store, only 46 percent use their mobile in-store for comparison shopping. Only 14 percent of survey respondents said they use mobile coupons, although 30 percent are more likely to use them around the holidays.

“The results of this study provide new evidence of expanding consumer reliance on mobile phones to manage their daily lives and to help in their decision-making process,” said James Briggs, CEO Briabe Media, in a press release. “Moreover, we are seeing a growing use of mobile phones to aid in shopping decisions, including for holiday purchases.”

By six percentage points, females (34 percent) consider their mobile phones more vital to their holiday shopping than do males (28 percent). But males, by a 2 percent point difference, are more likely than females to use their mobile phones to secure product information prior to entering a store.