Reading devices
marco.org
marco.org
I believe reading is felt to be less engaging than other forms of media, and therefore more easily interuptable.
I was on a domestic flight in Australia last week, and was surprised that my entire row kept reading their kindles through take-off and landing, and the flight attendants didn't say anything, even though the announcement of no electronic devices was still enforced.
[1] Lets ignore the risk to flight safety caused by letting passengers use electronics. Because that risk is so small one needs the LHC to find it.