Goodwin, B. (2018, February). Research Matters / Measuring Whats Inside.

Why don’t we measure students’ intrinsic motivation and curiosity? When 7,000 Chicago-area students sat down for a standardized test a few years ago, they got a pleasant surprise: If they did well, they’d receive rewards ranging from a trophy to $20. It worked: The students (randomly chosen to participate in a study) demonstrated, on average, 5—6 months more learning than students not promised rewards, leading the economists who conducted the study to suggest they’d solved “the urban school problem”—bribe kids and they’ll test better (Levitt et al., 2012).