During the third quarter of the year, ecommerce spending was down 2% year-over-year to $29.6 billion, according to new comScore research. As a result, for the first time ever, ecommerce spending declined over two consecutive quarters from the year prior.

"The third quarter showed negative marginal growth for the second consecutive quarter -- the first time on record we've witnessed sustained dips in U.S. e-commerce spending, small though the declines may be," said comScore chairman Gian Fulgoni.

"The good news is that these declines may finally be in our rearview mirror, as we anticipate marginally positive growth for the fourth quarter," Fulgoni added. "With retailers gearing up for the online holiday shopping bonanza, and a fourth quarter that will include easier comparisons against a year ago, we are hopeful that this Christmas season will be merrier than the last."

Over the past few years, free shipping has become a particularly critical incentive for stimulating online purchase behavior, and its importance has increased considerably during the recent economic downturn, according to comScore.

The past several quarters have seen the percentage of e-commerce sales transactions, including free shipping, increase from 31% in the first quarter of 2008 to 42% in the third quarter of 2009.

"Free shipping has become an increasingly essential promotion in the e-commerce marketer's toolkit," said Fulgoni. "With more than 40% of all e-commerce transactions now including free shipping, it's clear that consumers respond favorably to this incentive, and in many cases have come to expect it from retailers. The retailers who do not offer free shipping deals this holiday season may find themselves at a significant disadvantage versus those who do."

Despite recent signs of increased consumer confidence, 55% said the economy was still affecting major holiday purchase decisions, according to a survey conducted by About.com in September. Among the 1,056 participants, discount/coupons, free shipping with online purchases, and free gifts with purchase were ranked as the top three most compelling online holiday ad messages.

Consumers, the study found, are also shopping early for the holidays this year so they can do more comparison and less impulsive shopping. By September, 40% of respondents said they were already shopping for the holidays, while 40% said they planned to start their shopping in October and November.

Because of the economy, consumers are likewise spending more time shopping online and looking for deals this holiday season compared to last year. Nearly half -- 46% -- reported doing more comparison shopping online before purchasing.

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