Negative affect includes fear, frustration, sadness, discomfort, and anger. This factor reflects the degree to which a child is shy and not easily calmed. Anger and frustration is seen as early as 2 to 3 months of age. Anger and frustration, together, predict externalizing and internalizing difficulties. Anger, alone, is later related to externalizing problems, while fear is associated with internalizing difficulties. Fear as evidenced by behavioural inhibition is seen as early as 7–10 months of age, and later predicts children's fearfulness and lower levels of aggression.