Most people between the ages of 10-30 have been conditioned to pull out their phone during the slightest feeling of boredom, awkwardness, loneliness, or of course notification noise / buzz. It then becomes a question of which App gets opened first which usually is decided by the amount of 'reward' generated by the action.* Facebook
* Instagram
I can only speak to my demo, but the order is usually:
Tier 1:
* Text messaging
* Snapchat
Tier 1.5:
* Tinder
* Mobile games (only applies to a subset of users 'gamers')
Tier 2:
Tier 3:
* Browser
* Mobile games (most people)
* Other
You'll notice personal communications falls above content sharing. Snapchat is a definitive type of personal communication and is pretty firmly planted (IMO).