The Affect Grid (Russell et al., 1989) is a two dimensional mood scale, assessing positive affect by the perceived degree of valence and arousal. Participants place a single mark in a 19 19 grid defined by a y-axis describing arousal (extreme low to extreme high) and an x-axis describing valence (extreme low to extreme high pleasure). It allows for fast and repeated mood assessment, which is important as effects are expected to be subtle and short-lived.