storage system
At present, the accepted model to explain memory storage is the three-storage model of memory, which holds that memory processing has three different stages, namely sensory memory, short-term memory and long-term memory. The relationship between the three is shown in Figure 4.2. Information from the environment first reaches the sensory memory. If this information is noticed, it will enter short-term memory. It is in short-term memory that individuals reorganize and use this information and respond. In order to analyze the information stored in short-term memory, you will recall the knowledge stored in long-term memory. At the same time, if the information in short-term memory needs to be saved, it can also be saved in long-term memory by retelling. In Figure 4.2, the arrow indicates the running direction of information flow in the three-storage model.
First, sensory memory
Sensory memory, also known as sensory temporary memory or instantaneous memory, is the first direct impression that sensory information reaches the senses. Sensory registers can only store information of various senses in tens to hundreds of milliseconds. In the sense register, information may be noticed, encoded to gain meaning, and then continue to enter the next stage of processing activities. If they are not noticed or coded, they will disappear automatically.
All kinds of sensory information will continue to be stored in the sensory register for a period of time and play a role in its unique form. These storage forms are visual representation and sound representation, which are called video and sound image. Although they are preserved for a short time, they also have their own functions in life. For example, watching movies, it is video that helps us to see a group of pictures that appear one after another as a smooth and continuous picture. Most videos don't last more than a second, but in some cases, some videos can last longer. It depends on the intensity (such as brightness) of the stimulus. The greater the intensity of visual stimuli, the slower the video disappears.
Audio-visual memory and video memory are basically the same in nature, but the duration of audio-visual memory in sensory register is longer, up to several seconds. In this way, we can have more time to process phonetic information and realize the meaning of words. Research shows that video and sound images are faithful copies of physical stimuli and effective copies of information provided by sensory organs. Selective attention controls which information will be further processed and passed on to short-term memory.
Second, short-term memory.
Short-term memory, also known as working memory, is the core of information processing system. The information encoded in sensory memory is further processed after entering short-term memory, and then enters long-term memory that can be preserved for a long time from here. Information usually lasts only 20~30 seconds in short-term memory, but it can be kept if it is repeated. Retelling ensures that its delay disappears. Short-term memory stores information in use and plays a very important role in psychological activities. First of all, short-term memory plays the role of consciousness, letting us know what we are receiving and doing. Secondly, short-term memory enables us to integrate a large amount of information from the senses to form a complete image. Third, short-term memory plays the role of a temporary register when thinking and solving problems. For example, when doing a calculation problem, before doing the next step, temporarily store the calculation results of the previous step for final use. Finally, short-term memory preserves current strategies and wishes. All these enable us to take all kinds of complicated actions until we reach our ultimate goal. It is precisely because these important functions of short-term memory have been discovered that it has been renamed as working memory in most current studies.
(1) Coding form
The information in short-term memory is mainly stored in the form of sound codes. The classic research of Conrad (1964) is the best proof. He selected the letters B, C, P, T, V, F, M, N, S, X, etc. 10 as materials, randomly selected six letter sequences, and presented them to the subjects one by one in a visual way, asking them to remember. Then, the subjects were asked to recall in the order in which the letters were presented, and the errors in the memories were analyzed. The results show that the main mistake in memory is phonetic confusion. That is to say, letters with similar pronunciations have a high degree of confusion, such as mistaking B for P and V for B, while letters with different pronunciations have less confusion. This result shows that even if the stimulus is presented in a silent visual form, the information code of short-term memory still has novel properties. The visual images people see must be converted into sound codes in order to be better preserved in memory.
In addition to phonetic coding, people also have visual coding and semantic coding in short-term memory. But in short-term memory, auditory coding is dominant, especially for verbal information.
(2) Storage capacity
An important feature of short-term memory is its limited capacity. The capacity of short-term memory is limited, with only seven positive and negative chunks. Chunk refers to the most familiar cognitive unit, which is a stable psychological combination formed by people's continuous coding of stimuli. For a person, the number of material blocks with different lengths may be the same; However, the number of blocks formed by the same material may vary greatly for different people, depending on people's familiarity with the material. Therefore, the size of chunks is variable, and learning to combine more items into a meaningful chunk can greatly improve the memory span.
(3) Persistence of storage
In short-term memory, the retention time of information is limited. If they are not repeated, they will soon disappear. Peterson and Peterson (L.R. Peterson &; M.J.PeterSOIl, 1959) can illustrate this point.
In Peterson et al.' s experiment, the subject's task is to memorize meaningless syllables composed of three consonants, and then recall them after 18 seconds. Under normal circumstances, it is easy for subjects to complete this task correctly. But immediately after the stimulus was presented, a three-digit number was presented, and the subjects were asked to take this number as the starting point and subtract the reciprocal of 3 continuously until 18 seconds. At this time, the subjects were asked to recall letters, and the recall score was less than 20%, that is, the average recall was less than one letter. It was the countdown task that prevented the subjects from memorizing the materials repeatedly. Figure 4.3 is the result of a similar experiment, which shows that. To 18 seconds, all kinds of memories of keeping a distance. We see that with the extension of the interval, the memory performance drops rapidly. This shows that if it is not repeated, the information will soon fade even if it enters short-term memory.
Retelling is a necessary condition for information preservation, which plays a very important role in short-term storage and even long-term storage of information. There are two kinds of retelling: retentive retelling and elaborate retelling. Memory retelling refers to memorizing materials repeatedly, which can keep information in short-term memory for a period of time and make it active. But it may not be able to make information into long-term memory and keep it forever. Fine retelling refers to linking the memorized materials with the information stored in long-term memory, which can be preserved for a long time and easily recalled when needed.
Third, long-term memory.
Long-term memory (LTM) means that information will remain in the brain for a long time after being fully processed. Long-term memory is like a huge library, which contains all kinds of facts, representations and knowledge that we can use in the future. The capacity of long-term memory is astronomical and almost infinite. In long-term memory, information may be preserved forever. After 1960s, short-term memory has been widely studied. Long-term memory has been the focus of psychologists since the German psychologist Ebbinghaus first systematically studied memory in the19th century.
(1) encoding form
All information is transformed into long-term memory through short-term memory. An important and effective way to transfer information into long-term memory is to repeat it carefully, that is, to link the current information with the existing knowledge, give it a certain meaning, and organize the information. In fact, some information seems to be automatically encoded into long-term memory without conscious effort.
1. semantic code
The successful encoding of information into long-term memory is the result of relatively deep horizontal processing. In order to realize deep processing, people often ignore the physical characteristics or other details of stimuli and focus on the meaning of information. Therefore, auditory coding is mainly involved in short-term memory, while semantic coding is mainly involved in long-term memory. In other words, in long-term memory, people encode general meanings or general ideas more than remember specific details of things.
In long-term memory, semantic code is dominant. In a classic study, 24 pairs of closely related words (such as desks and chairs, chalk blackboard, etc. ) was disrupted to form a vocabulary of 48 words. Let the subjects recall these words freely after presentation. Although these words are disorganized when presented, people will still put closely related words together when recalling them. Even if "desk" and "chair" are separated by other words 17 when presenting, they are still put together when recalling. Moreover, the closer the relationship between pairs of words in vocabulary, the higher the proportion of accurate reproduction. Therefore, it can be proved that when the stimuli are presented, the subjects have been organized according to their semantic connections.
2. Visual code
In long-term memory, people also incorporate visual images into long-term memory. For example, people can easily remember pictures. One reason is that pictures have many obvious features, which can easily attract people's attention and then be received and encoded. Another reason is that people use visual and semantic codes to encode these stimuli at the same time, and using two codes to represent them can make use of more clues than using only one code to extract them, so the memory effect is better. Some people have a strong afterimage or photographic memory. Almost everything they see has an automatic, long-term, detailed and vivid appearance. About 5% of school-age children have residual images, while few adults have such memories. Why this ability to store detailed images disappears with age remains a mystery.
(B) Long-term memory storage mode
Long-term memory has a large capacity and a long duration, which is generally considered infinite. But memory does not passively accept and save information. To some extent, its storage is a process of building information.
A large amount of information in long-term memory is not like a very standard and tidy library, which is characterized by a hodgepodge framework and mixed relationships. The following example can help us understand it.
Zebra chrysanthemum potato wild boar fox rose bookshelf camel pencil cabbage
Wax gourd, tiger, coriander, Murray goat, clove, camellia, dolphin and peony.
Rubber bag onion elephant wintersweet tomato buffalo mouse jasmine pea
First, you try to remember 30 words in Table 4. 1 After a while, when you recall them, you will find that organizations play a role in long-term memory, that is, those words have been divided into four categories: animals, vegetables, stationery and flowers. Classification refers to the organization and memory of related or similar items according to certain categories, regardless of whether they are presented in an orderly or disorderly way. Secondly, when all kinds of information have a certain level of logical relationship in concept, it will form a multi-level concept system in memory according to its * * * characteristics, as shown in Figure 4.4. Research shows that this hierarchical organizational structure can effectively improve the memory effect. However, not all information can be well organized in a hierarchical system framework, and some knowledge is organized in an ambiguous system framework, which is called semantic network. It contains nodes representing various concepts and interrelated connecting lines, and the length of the connecting line indicates the tightness of the connection. According to the semantic network, when you think of a word, it is easy to think of other words related to it. This process is theoretically called diffusion activation.