For a complete treatment of the Candle Problem and several other cases of balderdash masquerading as science, go here.
The Candle Problem is an interesting experiment, and probably valid with respect to the performance of specific tasks against tight deadlines. I think the results apply whether the stakes are money or any other kind of prize. The experiment illustrates the “choke” factor, and nothing more profound than that.
I question whether the experiment applies to the usual kind of incentive (e.g., a commissions or bonus), where the “incentee” has ample time (months, years) for reflection and research that will enable him to improve his performance and attain a bigger commission or bonus (which usually isn’t an all-or-nothing arrangement).
There’s also the dissimilarity of the Candle Problem — which involves more-or-less randomly chosen subjects, working against an artificial deadline — and actual creative thinking — usually involving persons who are experts (even if the expertise is as mundane as ditch-digging), working against looser deadlines or none at all.