The explicit/implicit distinction in studies of visuomotor learning: Conceptual and methodological pitfalls

A ubiquitous problem in science - from a physicist estimating the position of an electron (Heisenberg, 1927) to a social scientist conducting opinion polling (Bishop, 2004) - is that the measurement process can change the measured quantity itself. In addition, variation in measurement methodology may inadvertently favor one component of the measured quantity over another, leading to different results even though the measured quantity has not changed - for example, both gross domestic product and gross national product assess the economic activity of a country, but focus on different components.