Reciprocity is the old “give a little get a little” idea. Human beings tend to be wired to respond kindly when others respond kindly to us.
In sales, this is sometimes used as a tactic – where sales people will offer drinks, food, or socially accepted “bribes” to encourage reciprocal behavior of the customer.
Wikipedia defines it as such: “As a social construct, reciprocity means that in response to friendly actions, people are frequently much nicer and much more cooperative than predicted by the self-interest model; conversely, in response to hostile actions they are frequently much more nasty and even brutal.”
In regards to daily interactions, people who are TOO nice or passive may “give to get”. For example, a nice person may be TOO NICE, going out of their way to help, to secretly get attention, affection, or “buy” friendship.
This is known to be called “covert agreements” – where the receiving person doesn’t know they are entering the agreement. We also call people who “do something to get something” are sometimes called “agenda-based.”
Agenda-based interactions is basically a form of falsely “expected reciprocity” which can cause a victim or dependent mindset when the agenda-based person doesn’t get what they intended.