In psychology, temperament broadly refers to consistent individual differences in behavior that are biologically based and are relatively independent of learning, system of values and attitudes. Some researchers point to association of temperament with formal dynamical features of behavior, such as energetic aspects, plasticity, sensitivity to specific reinforcers and emotionality. Temperament traits (such as Neuroticism, Sociability, Impulsivity, etc.) are distinct patterns in behavior throughout a lifetime, but they are most noticeable and most studied in children. Babies are typically described by temperament, but longitudinal research in the 1920s began to establish temperament as something which is stable across the lifespan.