If I understood the article in the link correctly this study was made during "2008".
I have a very poor memory but I believe that 6 years ago SmartPhone usage was no-where near what it is today. Today people use their smartphones for a plethora of Social Media applications which were not prevalent at the time.
Please, redo this study today and publish the result.
The article also does not state how the managed to ensure that no-one used their phones....