Brain scans have revealed that dopamine, the pleasure neurotransmitter is released every time we hear our phone beep. We get a buzz from the noise that tells us we have a message.
Dopamine controls the pleasure system part of the brain, but it also causes seeking behaviour. It makes us curious and helps us stay motivated. It also increases general level of arousal. In this case, phone beep serves as a cue. It tells us a reward is coming which sets off our dopamine system. This means we can become addicted every time we hear our phones beep.
Some advice from web psychologist Nathalie Nahai is to turn off notifications when on down-time with your friends and family so your focus is on them. Check out more from Nathalie @
http://www.slideshare.net/nathalienahai/mobile-mastery-26581286
Kent C. Berridge and Terry E. Robinson, What is the role of dopamine in reward: hedonic impact, reward learning, or incentive salience?: Brain Research Reviews, 28, 1998. 309–369.