Cover picture: A popular diversion in 17th century France as well as today, dice games inspired Blaise Pascal to define expected value as the product of the potential magnitude and probability of a valued outcome. Panels in the rolling dice shown depict mesolimbic regions (i.e., the midbrain, nucleus accumbens, and mesial prefrontal cortex), the activity of which correlates with the expected value of monetary outcomes, measured in humans undergoing event-related functional magnetic resonance imaging. To discover which of these regions shows sensitivity to magnitude versus probability terms, see the article by Knutson et al. in the May 11, 2005 issue (pages 4806–4812). Image credit: Jamil Bhanji.