, 2007; Shiffman, West, & Gilbert, 2004). However, there are also inconsistencies and ambiguities in the empirical literature (for reviews, see Perkins, 2009; Tiffany & Carter, 1998), which has made craving a selleck screening library somewhat controversial construct. These ambiguities may be because of measurement challenges in assessing craving. For example, craving is inherently subjective and, as a result, differences in ratings across individuals may not reflect true differences in the actual experience of craving. Furthermore, as a subjective experience, craving depends on introspection, which is fallible (Wilson & Dunn, 2004), and alternative motivational mechanisms may occur outside of awareness (Sayette et al., 2000).

Finally, craving has also largely been studied using single-item measures, which have several psychometric limitations compared with multi-item measures (Rosenberg, 2009; Sayette et al., 2000; Shiffman et al., 2004; Tiffany, 1992; Tiffany, Carter, & Singleton, 2000). For example, internal reliability cannot be calculated for single-item measures, and their semantic content is necessarily restricted. The field of behavioral economics unites concepts from microeconomics and psychology to understand behavior (Vuchinich & Heather, 2003). Particularly relevant in the context of assessing motivational aspects of addictive behavior are behavioral economic assays of substance demand (i.e., consumption in the context of escalating response cost) (for a review, see Hursh, Galuska, Winger, & Woods, 2005). The construct of substance demand is putatively multidimensional in nature (Bickel, Marsch, & Carroll, 2000; Hursh et al.

, 2005), consisting of five indices that reflect different facets of the underlying demand curve. These include Intensity (i.e., consumption at zero cost); Breakpoint (i.e., price at which consumption is completely suppressed); Elasticity (i.e., ��; slope of the demand curve); Omax (i.e., maximum expenditure); and Pmax (i.e., the price at which demand becomes elastic). In relation to the measurement of tobacco craving, behavioral economic indices of demand offer the potential for unique and complementary indices of motivation. Subjective craving and behavioral economic demand are theorized to reflect related but distinct GSK-3 aspects of acute drug motivation, a superordinate construct that also putatively comprises affective, physiological, and cognitive processes (MacKillop et al., 2012). This prospect is supported by a number of studies to date.