There are two possible interactions between emotion and cognition: effects of cognitions on emotions and effects of emotions on cognitions. Emotions are shorter and more intense than moods; they are elicited by stimuli the person is aware of. Moods last longer, are less intense, and are not tied to a specific stimulus. Differences in personality make some people experience some emotions more often and more intensely than other people. Emotional experience depends on bottom-up processes involving the occipital, parietal, and temporal lobes. It also depends on top-down processes involving the medial and dorsolateral prefrontal cortex, the anterior cingulate, and the amygdala. These brain regions form an interacting network. Mood states can be manipulated by asking participants to focus on emotional personal events or by presenting emotional music or movie clips. Many people around the world suffer from long-lasting or chronic anxiety. They often feel depressed as well. Research has focused on the possible contribution of attentional bias and interpretive bias.