Encoding is the process of perceiving information and bringing it into the memory system. Encoding is not simply copying information directly from the outside world into the brain. Rather, the process is properly conceived as recoding, or converting information from one form to another. The human visual system provides an example of how information can change forms. Light from the outside world enters the eye in the form of waves of electromagnetic radiation. The retina of the eye transduces (converts) this radiation to bioelectrical signals that the brain interprets as visual images. Similarly, when people encode information into memory, they convert it from one form to another to help them remember it later.
For example, a simple digit, such as 7, can be recoded in many ways: as the word seven, the roman numeral VII, a prime number, the square root of 49, and so on. Recoding is routine in memory. Each of us has a unique background and set of experiences that help or hinder us in learning new information. An ornithologist could learn a list of obscure bird names much more easily than most of us due to his or her prior knowledge about birds, which would permit efficient recoding.
Recoding is often the key to efficient remembering. To understand the concept of recoding, first try to remember the following series of numbers by reading it once out loud, closing your eyes, and trying to recall the items in their correct order: one, four, nine, one, six, two, five, three, six, four, nine, six, four, eight, one. Test yourself now. If you are like most people, you might have recalled around 7 of the 15 digits in their correct order. However, a simple recoding strategy would have helped you to recall them effortlessly. Write the numbers out in digits and you may notice that they represent the squares of the numbers of 1 to 9: 1, 4, 9, 16, 25, 36, 49, 64, 81. That is, 1 squared is 1, 2 squared is 4, 3 squared is 9, 4 squared is 16, and so on. Recoding the series of numbers as a meaningful rule the squares of the numbers 1 to 9 would have permitted you to remember all 15 digits.
Although this example is contrived, the principle that underlies it is universally valid: How well a person remembers information depends on how the information is recoded. Recoding is sometimes called chunking, because separate bits of information can be grouped into meaningful units, or chunks. For example, the five letters e, t, s, e, and l can be rearranged into sleet and one word remembered instead of five individual units.
Psychologists have studied many different recoding strategies. One common strategy that people often use to remember items of information is to rehearse them, or to repeat them mentally. However, simply repeating information over and over again rarely aids long-term retention although it works perfectly well to hold information, such as a phone number, in working memory. A more effective way to remember information is through effortful or elaborative processing, which involves thinking about information in a meaningful way and associating it with existing information in long-term memory.
One effective form of effortful processing is turning information into mental imagery. For example, one experiment compared two groups of people that were given different instructions on how to encode a list of words into memory. Some people were told to repeat the words over and over, and some were told to form mental pictures of the words. For words referring to concrete objects, such as truck and volleyball, forming mental images of each object led to better later recall than did rote rehearsal.
Thinking about the meaning of information is also a good technique for most memory tasks. Studies have found that the more deeply we process information, the more likely we are to recall it later. In 1975 Canadian psychologists Fergus Craik and Endel Tulving conducted a set of experiments that demonstrated this effect. The experimenters asked subjects to answer questions about a series of words, such as bear, which were flashed one at a time. For each word, subjects were asked one of three types of questions, each requiring a different level of processing or analysis. Sometimes subjects were asked about the word’s visual appearance: “Is the word in upper case letters?” For other words, subjects were asked to focus on the sound of the word: “Does it rhyme with chair?” The third type of question required people to think about the meaning of the word: “Is it an animal?” When subjects were later given a recognition test for the words they had seen, they were poor at recognizing words they had encoded superficially by visual appearance or sound. They were far better at recognizing words they had encoded for meaning. (See the accompanying chart entitled “Depth of Processing and Memory.”)
Although some information requires deliberate, effortful processing to store in long-term memory, a vast amount of information is encoded automatically, without effort or awareness. Every day each of us encodes and stores thousands of events and facts, most of which we will never need to recall. For example, people do not have to make a conscious effort to remember the face of a person they meet for the first time. They can easily recognize the person’s face in future encounters. Studies have shown that people also encode information about spatial locations, time, and the frequency of events without intending to. For instance, people can recognize how many times a certain word was presented in a long series of words with relative accuracy.
People have developed many elaborate and imaginative recoding strategies, known as mnemonic devices, to aid them in remembering information. For descriptions of mnemonic devices, see the Ways to Improve Memory section of this article.