It’s fairly easy to describe someone who is angry. An angry person usually has a tense expression on his face. He might be yelling, with broad gestures or clenched fists. Someone who is sad might be crying, and someone who is happy is probably smiling or laughing. Emotions affect actions in predictable – but also unpredictable – ways.

Emotions Influence Thought

Certain situations trigger emotional reactions, which in turn affect the way a person thinks, according to the Harvard Graduate School of Education. This can be a good thing, as a person's initial emotional reaction can allow him to react quickly if he is in danger. Sometimes, there just isn't time to think it through first. Other times, the way emotions trigger thoughts is a good thing. For example, if a person feels sorrow over another person's troubling situation, she might think of a way to help the person in trouble. But in other cases, people -- especially students -- may need to be taught to analyze the way they think in response to their emotions. If a student feels sad over a failed test and thinks that he will never pass it, he needs to change his thinking to find a way to solve the problem, such as telling himself that with a little help he will be able to understand the concepts in the test. Taking the time to analyze the situation can change thoughts – and therefore, actions – to a more socially acceptable or productive response.

Emotions Trigger Physical Responses

Emotions affect actions because actions allow feelings to be expressed. In fact, repressing feelings is not healthy, according to the American Academy of Family Physicians, and it can lead to a whole host of physical and emotional problems. Most people do express their feelings by engaging in certain actions – having a good cry when feeling sad, frowning when frustrated and giving a “high five” to someone when feeling confident are all examples of how people express their emotions. These responses to emotions are usually healthy, but learning how to respond appropriately to emotions can sometimes be difficult – especially for young children, who usually need to be taught how to respond to emotions such as anger or love in socially acceptable ways.

Emotions Determine Decisions

Emotions can affect the decision-making process. Negative emotions in particular can make some people feel as if they don’t have very many good options. Depression, anxiety and anger may make a person feel trapped, according to psychiatrist Peter Zafirides in an article titled "How Our Emotions Can Affect Our Decision Making Ability," posted on KevinMD.com. In such cases, these and other negative emotions can lead a person to make bad decisions. In contrast, when a person is feeling content, happy and secure, she is more likely to make thoughtful, positive decisions.

Emotions Respond to Actions

The link between actions and emotions is actually a two-way street. Just as emotions affect actions, so actions can affect emotions. According to a "Scientific American" article titled “Smile! It Could Make You Happier,” actions – in particular, facial expressions – can create emotions. A 2009 study by psychologists at the University of Cardiff in Wales found that participants whose faces were numbed by botox injections -- making them unable to frown -- reported feeling happier than patients who were able to form unhappy facial expressions. In a December 2010 article in "U.S News," psychologist and research director David Lewis of Mindlab International in Brighton, England, states that smiling makes a person feel positive and optimistic.