The advent of digital media and the growing collection of digital documents have had a profound impact on how we read.
Findings – With an increasing amount of time spent reading electronic documents, a screen-based reading behavior is emerging. The screen-based reading behavior is characterized by more time spent on browsing and scanning, keyword spotting, one-time reading, non-linear reading, and reading more selectively, while less time is spent on in-depth reading, and concentrated reading. Decreasing sustained attention is also noted. Annotating and highlighting while reading is a common activity in the printed environment. However, this “traditional” pattern has not yet migrated to the digital environment when people read electronic documents.
Source: Reading behavior in the digital environment: Changes in reading behavior over the past ten years
If you want an in-depth argument about how the internet is changing our reading habits, see the argument between Clay Shirkey and Nick Carr: Does the internet make you smarter or Dumber?