Memory is essentially the capacity for storing and retrieving information. Three processes are involved in memory: encoding, storage, and retrieval. All three of these processes determine whether something is remembered or forgotten.
Processing information into memory is called encoding. People automatically encode some types of information without being aware of it. For example, most people probably can recall where they ate lunch yesterday, even though they didn’t try to remember this information. However, other types of information become encoded only if people pay attention to it. College students will probably not remember all the material in their textbooks unless they pay close attention while they’re reading.
There are several different ways of encoding verbal information:
After information enters the brain, it has to be stored or maintained. To describe the process of storage, many psychologists use the three-stage model proposed by Richard Atkinson and Richard Shiffrin. According to this model, information is stored sequentially in three memory systems: sensory memory, short-term memory, and long-term memory.
Sensory memory stores incoming sensory information in detail but only for an instant. The capacity of sensory memory is very large, but the information in it is unprocessed. If a flashlight moves quickly in a circle inside a dark room, people will see a circle of light rather than the individual points through which the flashlight moved. This happens because sensory memory holds the successive images of the moving flashlight long enough for the brain to see a circle. Visual sensory memory is called iconic memory; auditory sensory memory is called echoic memory.
Some of the information in sensory memory transfers to short-term memory, which can hold information for approximately twenty seconds. Rehearsing can help keep information in short-term memory longer. When people repeat a new phone number over and over to themselves, they are rehearsing it and keeping it in short-term memory.
Short-term memory has a limited capacity: it can store about seven pieces of information, plus or minus two pieces. These pieces of information can be small, such as individual numbers or letters, or larger, such as familiar strings of numbers, words, or sentences. A method called chunking can help to increase the capacity of short-term memory. Chunking combines small bits of information into bigger, familiar pieces.
Example: A person confronted with this sequence of twelve letters would probably have difficulty remembering it ten seconds later, because short-term memory cannot handle twelve pieces of information: HO TB UT TE RE DP OP CO RN IN AB OW L However, these letters can be easily remembered if they’re grouped into six familiar words, because short-term memory can hold six pieces of information: HOT BUTTERED POPCORN IN A BOWL
Psychologists today consider short-term memory to be a working memory. Rather than being just a temporary information storage system, working memory is an active system. Information can be kept in working memory while people process or examine it. Working memory allows people to temporarily store and manipulate visual images, store information while trying to make decisions, and remember a phone number long enough to write it down.
Information can be transferred from short-term memory to long-term memory and from long-term memory back to short-term memory. Long-term memory has an almost infinite capacity, and information in long-term memory usually stays there for the duration of a person’s life. However, this doesn’t mean that people will always be able to remember what’s in their long-term memory—they may not be able to retrieve information that’s there.
Imagine what would happen if a psychology textbook weren’t organized by section, by chapter, or in any other way. Imagine if the textbook didn’t have a table of contents or an index. If the textbook just contained lots of information in a random order, students would have difficulty finding a particular concept, such as “encoding of memory.” They’d know the information was in there somewhere, but they’d have trouble retrieving it.
Long-term memory stores much more information than a textbook, and people would never be able to retrieve the information from it if it weren’t organized in some way.
Psychologists believe one way the brain organizes information in long-term memory is by category. For example, papaya may be organized within the semantic category fruit. Categories can also be based on how words sound or look. If someone is struggling to remember the word papaya, she may remember first that it’s a three-syllable word, that it begins with the letter p, or that it ends with the letter a.
Long-term memory organizes information not only by categories but also by the information’s familiarity, relevance, or connection to other information.
Retrieval is the process of getting information out of memory. Retrieval cues are stimuli that help the process of retrieval. Retrieval cues include associations, context, and mood.
Because the brain stores information as networks of associated concepts, recalling a particular word becomes easier if another, related word is recalled first. This process is called priming.
Example: If Tim shows his roommate a picture of sunbathers on a nude beach and then asks him to spell the word bear, the roommate may be more likely to spell bare because the picture primed him to recall that form of the word.
People can often remember an event by placing themselves in the same context they were in when the event happened.
Example: If a woman loses her car keys, she may be able to recall where she put them if she re-creates in her mind exactly what she did when she last came in from parking her car.
If people are in the same mood they were in during an event, they may have an easier time recalling the event.