Because there's a strong dopamine rush triggered by the thought of seeing those twitter feeds, and your brain is particularly starved for dopamine at the time (maybe you're tired, bored etc). That triggering is the result of the same activity reinforced hundreds of time, so a strong neuronal association has been made between twitter and the reward. Stop using twitter (or whatever maladaptive addictive behavior you'd want to eliminate) for a few months, and those associations will fade.
If you are engaged in a meaningful conversation for instance, you won't feel such a strong urge to check twitter.
Because there's a strong dopamine rush triggered by the thought of seeing those twitter feeds, and your brain is particularly starved for dopamine at the time (maybe you're tired, bored etc). That triggering is the result of the same activity reinforced hundreds of time, so a strong neuronal association has been made between twitter and the reward. Stop using twitter (or whatever maladaptive addictive behavior you'd want to eliminate) for a few months, and those associations will fade.
If you are engaged in a meaningful conversation for instance, you won't feel such a strong urge to check twitter.