Emotions unfold from an appraisal process with an initial bias toward negative stimuli. Positive emotion stimuli motivate approach behavior, while negative stimuli motivate avoidance behavior. Emotions are linked to facial expressions that either convey people's affect or people's social motives; for example, tears can convey sadness or a plea for help. Facial expressions result from innate tendencies modified by a cultural accent. Emotions motivate individuals to achieve the aim of an emotion. Affect can influence an individual's perception, thoughts, and decisions. Negative emotions prompt immediate action, while positive emotions, such as happiness, act like positive incentives. However, people eventually return to their set point of level happiness as if they are on a hedonic treadmill. People prefer happiness or subjective well-being in moderation. Happiness can also increase motivation.