Tell us something important and direct attention to event. Emotions such as fear or anger emergency arousal system that increase chances of survival. Positive emotions form lasting social relationships and broaden thinking and behaviour so that we explore, consider new ideas. Parents irritated when baby cry, they are physiological aroused themselves -> key survival value for baby. Positive emotions of baby increase parents" feelings of love -> child"s biological and emotional needs satisfied. Children less than 1 year old respond with negative affect to vocal expressions of fear by their mother. By 2 years old, they comfort mothers" real or simulated signs of distress. 550 words in english that refer to positive and negative emotional states. We may become physically stirred up as in fear joy or anger or experience decrease arousal as in contentment or depression: emotions include behaviour tendencies. Some are expressive behaviours others are instrumental behaviours, ways of doing something about the stimulus that aroused the emotion.