There is no whitepaper on it, but I can explain it.
Hive has what is called a reverse auction in addition to time based curation. Also note curation rewards are 50% of the post rewards.
The earlier you vote, the more curation rewards you earn as you can only earn rewards on those who vote after you (and an amount of your specific vote). This encourages people to vote as early as possible to get the most rewards. To prevent people from blindly voting on content just to earn the most rewards, the reverse auction penalizes anyone who votes within the first 5 minutes with a sliding scale. This system encourages people to vote on the most popular content as early as possible but not too early that you forfeit all your rewards.
If you vote at 0 minutes, you forfeit 100% of your curation rewards. If you vote at 5 minutes, you forfeit 0%. 2.5 minutes you forfeit 50%. It is a linear reduction from 0 minutes to 5 minutes. (Historically it used to be 30 minutes, but then was changed to 15 minutes, then 5 minutes). Future hard fork will likely change it to 2 hours and remove remove any benefit to being "first" in the first two hours, in other words anyone who votes within 2 hours will get the same curation reward based on their stake (linear rewards, which explain in a second). After 2 hours, will revert back to normal time based curation rewards.
There is also a curve on Hive, in short this means posts with higher rewards will snowball and get even more rewards and low reward posts will have a more difficult time getting more rewards until it hits a certain threshold (around $10 they intercept). This curve is to discourage spamming for low rewards as it is difficult to find and counter this abuse. Some tribes implement a curve on post rewards, some do not.
Leo (and my tribe STEMGeeks) uses a linear distribution model, where you earn 50% of your vote regardless of when you vote. This encourages people to vote for what is "good" rather than what is profitable, and tries to encourage manual voting. It does not however take in account the lazy factor, and people just sticky votes as it no longer matters where you put them. The simple fact is, manual voting is a full time job and can take hours a day.
Both systems have their benefits and their problems.