The relationship of approach/avoidance motivation and asymmetric frontal cortical activity: A review of studies manipulating frontal asymmetry

•Asymmetric patterns of frontal cortical activity have served as a proxy for an organism's motivational direction.•We review manipulations of frontal asymmetry including neurofeedback, muscular contractions and brain stimulation.•These methods allow for stronger causal inferences about the role of a frontal asymmetry in approach-avoidance motivation.

The balance between activity in the left and right frontal cortex, commonly referred to as asymmetric frontal cortical activity, has served as a proxy for an organism's motivational direction (i.e., approach vs. avoidance). Many studies have examined the influence of the manipulation of motivational direction on asymmetrical frontal cortical activity and found results consistent with the idea that greater relative left (right) frontal cortical activity is associated with approach (avoidance) motivation. We critically review literature employing physical (versus psychological) manipulations of frontal asymmetry using a variety of methodologies including neurofeedback training, muscular contractions, and non-invasive brain stimulation. These reviewed methods allow us to make stronger causal inferences regarding the role of asymmetric frontal cortical activity in approach and avoidance motivation.