Work in our laboratory (Doremus-Fitzwater & Spear, 2008) has begun to explore potential age differences in incentive salience for natural rewards using assessment of sign-tracking behavior (Flagel et al., 2007, 2008, 2009). Sign-tracking occurs when a cue associated with an appetitive reward elicits approach and goal-directed behavior towards the cue itself, a cue-directed behavior that can become excessive over time (Tomie, 1995). Flagel and colleagues have hypothesized that expression of approach and goal-directed behavior to such cues (rather than to the spatial location of impending reward delivery) is indicative of enhanced incentive salience for the cue (for review see Flagel et al., 2009).
