Emotions are sometimes contrasted with moods .
People appear to differ in their susceptibility to various emotions and mood states.
Some people tend to be frequently morose or depressed, whereas other people tend to be perpetually sanguine and optimistic. In short, people may differ according to temperament . Possible sources for differences in temperament might include genetic factors, cultural environment, or significant life experiences. Emotions confer meaning to the events of our lives, and add passion and conviction to our actions. The fast and slow brain responses reflect a basic neuro-evolutionary understanding of brain functioning.