How to use it
Points, badges, commissions and prizes say "we saw it", never "do this to get that". Give choice in how; reward what's already happening, with a note on why it mattered.
How sure we are
S Evidence: strong. Large trials or many studies, pointing the same way.
Sources
Incentives raise quantity more than quality (Cerasoli et al. 2014) · controlling tangible rewards lower interest (Deci, Koestner & Ryan 1999, 128 studies).
Not medical, legal or financial advice.