If it's not left, it's right: Electroencephalograph asymmetry and the development of emotion.

Recent studies suggest that an initial component involving stimulus evaluation may precede subsequent steps in the generation of emotion. This article presents a model for the development of emotion that involves an initial decision of approach or withdrawal, which results in motor programs, including facial expression, that facilitate either approach or withdrawal. With development, more complex emotions arise, as products of these basic initial responses and interaction with the environment. Evidence is presented that suggests that there are brain asymmetries (as measured by scalp recorded EEG activity) localized to the frontal region that are associated with the generation of emotion in infants. Variability in the pattern of EEG asymmetry between infants may be an important marker of differences in temperament.