I examine how financial incentives interact with intrinsic motivation and especially cognitive abilities in explaining heterogeneity in performance. Using a forecasting task with varying cognitive load, I show that the effectiveness of high-powered financial incentives as a stimulator of economic performance can be moderated by cognitive abilities in a causal fashion. Identifying the causality of cognitive abilities is a prerequisite for studying their interaction with financial and intrinsic incentives in a unifying framework, with implications for the design of efficient incentive schemes.