Overjustification Effect

People are deeply motivated to do certain things because of their intrinsic value (i.e., how it makes them feel), rather than an obvious external benefit (like money).

For example, you may pick up litter that you see in the street, because you want a cleaner neighbourhood. But you may resent being paid to pick up litter.

The overjustification effect, explains how the 'incentive' distorts the original intent, despite objectively being the same task.

A more product-related example would be being financially incentivised to invite your friends to an app.

If you genuinely believe that they'd benefit from the service, sharing it is a well-intended act. Your incentive is to help your friend (and possibly making your experience better).

But if that same app paid you £3 for every referral, your friend's account has a value. You may perceive an invitation as being worth more than £3.

It may also feel disingenuous, despite being the same action.