A normal function of emotion is to enhance memory in order to improve recall of experiences that have importance or relevance for our survival. Emotion acts like a highlighter pen that emphasizes certain aspects of experiences to make them more memorable. Memory formation involves registering information (encoding), processing and storage, and retrieval.
Emotion affects all the phases of memory formation. Here's how.
1. Attention: Attention guides our focus to select what’s most relevant for our lives and is normally associated with novelty. Nothing focuses the mind like surprise. For example, although one may thoroughly enjoy a particular conversation, the same conversation a second time around would be dull. Emotional intensity acts to narrow the scope of attention so that a few objects are emphasized at the expense of many others. Focusing upon a very narrow area allows for an optimal use of our limited attentional capacity.
2. Consolidation of a memory: Most of the information we acquire is forgotten and never makes it into long-term memory. When we learn a complex problem, the short-term memory is freed up and the action becomes automatic. Emotionally charged events are remembered better than those of neutral events. You will never forget some events, such as the joy of the birth of your first child, or the horror of the 9/11 terrorist attack. The stress hormones, epinephrine and cortisol, enhances memory and consolidates memory contents. In evolutionary terms, it’s logical for us to imprint dangerous situations with extra clarity so that we may avoid them in the future.
3. Memory recall: Memories of painful emotional experiences linger far longer than those involving physical pain. There is an old saying that “sticks and stones can break your bones, but words can never hurt you.” To the contrary, evidence shows that hurt feelings could be worse than physical pain. In the words of Maya Angelou: “I've learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel.” In fact, there is an evidence that acetaminophen (e.g., Tylenol) works not only on physical pain, but also on emotional pain.
4. Priming: Past memories are often triggered or primed by one’s environment. Priming refers to activating behavior through the power of unconscious suggestion. Researchers have found that people who were made to think of self-discipline (by having to unscramble sentences about it) immediately made more future-oriented snack choices than those given sentences about self-indulgence. In this case, the goal stored in long-term memory is retrieved and placed in short-term (or working) memory. Similarly, the concept of a library causes people to speak more softly.
5. Mood memory: Our current emotional state facilitates recall of experiences that had a similar emotional tone. When we are in a happy mood, we tend to recall pleasant events and vice versa. This is because moods bring different associations to mind. For example, recalling positive childhood experiences while in a good mood. Being in a bad mood primes a person to think about negative things.
6. Blanking out: Stress can lead to memory deficit, such as the common experience of mentally blanking during a high-pressure examination or interview. Thus, worrying about how you will perform on a test may actually contribute to a lower test score. In general, anxiety influences cognitive performance in a curvilinear manner (an inverted U-curve). This phenomenon is known as the Yerkes– Dodson law. That is, when levels of arousal are too low (boredom) and when levels of arousal are too high (anxiety or fear) performance is likely to suffer. Under situations of low arousal, the mind is unfocused. In contrast, under situations of high stimulation, the focus of attention is too narrow, and important information may be lost. The optimal situation is moderate arousal.
7. Duration neglect (Peak-End rule): The way we remember events is not necessarily made up of a total of every individual moment. Instead, we tend to remember and overemphasize the peak (best or worst) moment and the last moment, and neglect the duration of an experience. This explains why normally the bad ending ruins the whole experience. For example, when you remember your summer vacation to Canada, there is just too much information to evaluate whether it was an enjoyable trip. So, you apply the peak-end rule and you more heavily weight the best moment and the most recent moment.
In sum, much of learning takes place in the form of emotional learning. To make our memory stronger, it helps to attach emotional significance to objects and actions we experience.