A leading magazine audience research group (GfK MRI) has released some results (from their large-scale survey on media use by US adults) that suggests that people who own eReaders or tablets are also heavy readers of print media and are more likely to be heavy Internet users. Individuals who own eReaders are 23% more likely to be heavy readers of magazines, and 63% more likely to be heavy users of newspapers, than the average adult in the U.S. They are slightly less likely (4%) to be heavy radio listeners, but significantly less likely (35%) to be classified as a heavy TV viewer. The numbers are similar for the smaller proportion of American adults who own a tablet device - 66% more likely to be heavy magazine readers, 54% more likely to be heavy newspaper readers, slightly less likely to be radio users (8%) and 37% less likely to be heavy TV users.
As one might suspect, those who own eReaders primarily use them to read books, although some have also used their device to read digital versions of magazines (15%) and newspapers (14%) within the last 6 months. Tablet owners also used their devices for reading books (57% used their tablet to read a book in the last 6 months) - however tablet owners were much more likely to also use their device to read magazines (39%) and newspapers (41%).
My interpretation is that the newspaper and magazine industry should not fear the rapid adoption of eReaders and Tablets - they seem to be encouraging a growth in reading that is likely to carry through to print media. There also appears to be a much stronger market for Tablet-oriented digital versions of newspapers and magazines than for versions designed for eReaders. The real bad news in these results is for the TV industry, and the idea that those with eReaders or Tablets are significantly less likely to be heavy TV users. While these statistics don't directly show a decline in viewing, I think that these digital devices offer convenient alternatives for the entertainment or escape gratifications that TV has come to dominate. In addition, Tablets allow delivery of video content on demand, and in that sense can directly compete with traditional TV for viewers.
Source: "Owners of eReaders and Tablets Are Heavy Readers of Printed Versions of Magazines and Newspapers," press release, GfK MRI
The research firm has provided a short video explaining these results. It's available here.