Nearly 40 percent of consumers visit Facebook and Twitter to supplement the news, information or deals they receive via email marketing, according to a new study by ExactTarget.

"Consumers don't silo their engagement with brands to a single channel, instead they tend to 'layer' marketing channels on top of one another to meet their different objectives," said Morgan Stewart, principal, ExactTarget's research and education group.

"The things that motivate consumers to go online initially dictate where and how they choose to engage with brands - whether that be email, Facebook or Twitter."

More than 90 percent of consumers that are a fan of, or "like," at least one brand on Facebook also receive at least one permission-based marketing email per day. In addition, more than 75 percent of consumers that follow at least one brand on Twitter subscribe to at least one brand's email marketing.

Other highlights of the study include:

*Nearly half of consumers who engage with brands via Twitter do so silently, regularly reading tweets even though they do not have their own Twitter account.

*45 percent of mothers with children living in the home identify themselves as 'Deal Seekers' and on average are a fan of 10 brands on Facebook, follow 10 companies on Twitter and receive 14 permission-based marketing emails daily.

*33 percent of consumers identify themselves as Info Seekers, influenced most heavily by product reviews and other forms of user-generated content.

*While 28 percent of consumers under the age of 25 identify themselves as "social butterflies" and fan the most brands on Facebook, they are more likely to buy from companies that send them permission-based email.

"Simply understanding demographics of a customer group is no longer enough," said Tim Kopp, ExactTarget's chief marketing officer.

"By bridging the gap between demographics and consumer motivations, the Social Profile research identifies unique personas that give marketers an entirely new level of understanding of consumer behavior."