While online shopping soared during the holiday season, American consumers actually spent significantly less on each purchase, a bank study shows.

Online shoppers spent an average of $36 for each transaction during the holiday season this year, down 9 percent from 2010, according to a study released Thursday by Chase Paymentech, J.P. Morgan & Chase's credit card processing unit .

The decline in the amount each transaction generally correlated with a rise in total transactions, Paymentech Executive Vice President Mia Shermoff told the International Business Times. The study revealed that 37 percent more transactions were conducted online during November and December compared to the same period in 2010.

Consumers continue to be more comfortable shopping online, she said. The decline of ticket sales (the amount spent on each transaction) is really about a change in the shopping behavior of online consumers.

While some of that growth in transaction volume came from new online shoppers, some growth came from online purchases for more routine items such as video games and movies, Shermoff said. She also said customers may have visited more Web sites to shop, thus lowering the amount spent at each site.

The rise of purchases through a smartphone may have also contributed to the increase in transaction frequency, comScore analyst Andrew Lipsman told IBTimes. His digital analytics firm released a study last month indicating that 38 percent of smartphone owners have used their devices to make a purchase.

The study noted the most common purchases on smartphones were digital purchases such as music, eBooks, and TV shows -- typically inexpensive items. Since each item costs less, people purchased those items more frequently.

The rise of free shipping likely played a role too. Besides driving down the cost of each transaction, Lipsman said free shipping also likely played a role in boosting transaction frequency, as it removed the cost barriers that prevented people from making small purchases online.  

CLARIFICATION: Online shoppers spent an average of $36 for each online transaction during the holiday season. A previous version of the article only said online shoppers spent $36 on each transaction.