It includes four largely independent dimensions: (1) Novelty Seeking (NS), representing behavioural activation in response to novelty and signals of reward or relief of punishment; (2) Harm Avoidance (HA), referring to behavioural inhibition in response to signals of punishment or non-reward; (3) Reward Dependence (RD), reflecting the maintenance of socially rewarded behaviour; and (4) Persistence (P), describing the maintenance of behaviour despite only intermittent reinforcement.