People who own smartphones are most likely to be hyper users of email and Facebook: 45% of smartphone owners check email constantly during the day (via multiple devices) and 28% check Facebook with the same frequency, according to a survey from ExactTarget.

Fewer non-smartphone owners check email (28%) and Facebook (12%) throughout the day.

More smartphone owners check into Twitter constantly during the day: 5% do, whereas just 2% of non-smartphone owners check in that frequently.

Below, other findings form ExactTarget's survey of 1,500 Internet users adults age 15 and older.

Email, Facebook User Segments

Email users are less inclined to check email throughout the day, regardless of device:

• 24% of email users check email via home computer constantly during the day.
• 16% check email via home or work computer throughout the day.
• 11% check email via mobile phone throughout the day.
  
• 2% check email via iPad or other tablet computer throughout the day.

Facebook users, meanwhile, check email more often than Facebook throughout the day:

• 25% check email via home computer constantly during the day.
• 17% check email via work or school computer throughout the day.
• 14% check email via mobile phone throughout the day.

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Checking Into Facebook

Meanwhile, just 17% of Facebook users check Facebook constantly during the day via home computer.

Employees and students aren't checking Facebook at work or school too often, either: Only 4% check Facebook throughout the day while at work or school, and only 18% check Facebook at least once a day when they're on the job or in class.

How Users Interact With Messages

When using email, most people (83%) read back (chronologically) to their last unchecked message.

But Facebook and Twitter have much greater message loss, likely because of the persistent, feed-like nature of their message presentation layer: 61% of Facebook users scroll back down to the last unread wall post and 56% of Twitter users scroll down to their last unread tweet.

About the data: Findings are from ExactTarget's survey of 1,500 Internet users age 15+, conducted from Dec. 2010 to Jan. 2011.