Most players have escalators written into their contracts, ranging anywhere from playing time to achievements (statistical, awards, and Pro Bowl).
Escalators are a lot like incentives, with the primary difference being how that money is applied. Escalators increase a player's contract for the following season and gives teams a little more control on financial distribution -- for one thing, most escalators are not guaranteed. Incentives force teams to adjust for possible payment because it's tied into that team's salary cap.
A good agent will ask for incentives but teams clearly favor escalators.
According to OverTheCap.com, three Bengals earned escalators this season (it's unknown what they were).
Clint Boling - $744,000
Adam Jones - $500,000
Jermaine Gresham - $500,000
NOTE: More numbers/information could be released soon.
Over 80 players achieved escalators in 2013 in the NFL, raising their salary for the 2014 season. Andre Johnson earned the biggest increase with a $3.5 million escalator. Lions defensive tackle added a $1 million escalator for making the 2014 Pro Bowl.