Task: Classify the mental state of the tweeter based on the tweet, determining if it is 'neutral or no emotion' or characterized by any of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: In inter-group relationships, #anger makes people think in more negative and prejudiced terms about outsiders.
This tweet contains emotions: 
anger, disgust, optimism, pessimism, sadness