What a great question! When we were young, chores were expected--demanded--and you avoided them at your peril. ha.
My sister's kids began to do chores at a very early age and they didn't care for it much but not doing them would result in some negative feedback, if you know what I mean.
Because I didn't like that type of motivation when I was young, I tried not to use it on my own children. I used the ol' Tom Sawyer trick of making it seem like fun so they wanted to get in on it. *wink*
And then, we made a game of it by "blitzing" the house to see how fast we could get it all done. We'd give ourselves only a certain amount of time to finish. But there was a big reward afterward like going out...or having friends over...or playing fun games in the clean, clear spaces.
Praise works best to give kids a sense of accomplishment and pride in their work. Also, it's important for them to enjoy a clean environment all the time so when things get messy or dirty, they don't like it and will clean up by themselves. Kids are adaptable and will get used to a messy home fairly quickly and won't see the need to straighten things up.
Older kids need different types of motivation. We divide up the chores now and everyone feels a sense of belonging because the whole family counts on each person to chip in and get the job done. Praise and appreciation are the best motivators for every age.
I don't like the idea of bribing or paying kids to be part of the family. Help out. Everyone benefits. The thought is that we keep a clean home for all of us to enjoy.