In cognitive psychology, chunking is a process by which small individual pieces of a set of information are bound together to create a meaningful whole later on in memory. The chunks, by which the information is grouped, are meant to improve short-term retention of the material, thus bypassing the limited capacity of working memory and allowing the working memory to be more efficient. A chunk is a collection of basic units that are strongly associated with one another, and have been grouped together and stored in a person's memory. These chunks can be retrieved easily due to their coherent grouping. It is believed that individuals create higher-order cognitive representations of the items within the chunk. The items are more easily remembered as a group than as the individual items themselves. These chunks can be highly subjective because they rely on an individual's perceptions and past experiences, which are linked to the information set. The size of the chunks generally ranges from two to six items but often differs based on language and culture.
According to Johnson (1970), there are four main concepts associated with the memory process of chunking: chunk, memory code, decode and recode. The chunk, as mentioned prior, is a sequence of to-be-remembered information that can be composed of adjacent terms. These items or information sets are to be stored in the same memory code. The process of recoding is where one learns the code for a chunk, and decoding is when the code is translated into the information that it represents.
The phenomenon of chunking as a memory mechanism is easily observed in the way individuals group numbers, and information, in day-to-day life. For example, when recalling a number such as 12101946, if numbers are grouped as 12, 10, and 1946, a mnemonic is created for this number as a month, day, and year. It would be stored as December 10, 1946, instead of a string of numbers. Similarly, another illustration of the limited capacity of working memory as suggested by George Miller can be seen from the following example: While recalling a mobile phone number such as 9849523450, this might be broken down into 98 495 234 50. Thus, instead of remembering 10 separate digits that are beyond the putative "seven plus-or-minus two" memory span, four groups of numbers need to be remembered instead. An entire chunk can also be remembered simply by storing the beginnings of a chunk in the working memory, resulting in the long-term memory recovering the remainder of the chunk.
Modality effect A modality effect is present in chunking. That is, the mechanism used to convey the list of items to the individual affects how much "chunking" occurs.
Experimentally, it has been found that auditory presentation results in a larger amount of grouping in the responses of individuals than visual presentation does. Previous literature, such as George Miller's "The Magical Number Seven, Plus or Minus Two: Some Limits on our Capacity for Processing Information" (1956) has shown that the probability of recall of information is greater when the chunking strategy is used. As stated above, the grouping of the responses occurs as individuals place them into categories according to their inter-relatedness based on semantic and perceptual properties. Lindley (1966) showed that since the groups produced have meaning to the participant, this strategy makes it easier for an individual to recall and maintain information in memory during studies and testing. Therefore, when chunking is used as a strategy, one can expect a higher proportion of correct recalls.
Memory-training systems, mnemonic Various kinds of memory-training systems and mnemonics include training and drills in specially designed recoding or chunking schemes. Such systems existed before Miller's paper, but there was no convenient term to describe the general strategy and no substantive and reliable research. The term chunking is now often used in reference to these systems. As an illustration, patients with Alzheimer's disease typically experience working memory deficits; chunking is an effective method to improve patients' verbal working memory performance. Patients with schizophrenia also experience working memory deficits which influence executive function; memory training procedures positively influence cognitive and rehabilitative outcomes. Chunking has been proven to decrease the load on the working memory in many ways. As well as remembering chunked information easier, a person can also recall other non-chunked memories easier due to the benefits chunking has on the working memory. For instance, in one study, participants with more specialized knowledge could reconstruct sequences of chess moves because they had larger chunks of procedural knowledge, which means that the level of expertise and the sorting order of the information retrieved is essential in the influence of procedural knowledge chunks retained in short-term memory. Chunking has been shown to have an influence in linguistics, such as boundary perception.
Efficient chunk sizes According to the research conducted by Dirlam (1972), a mathematical analysis was conducted to see what the efficient chunk size is. The size range that chunking holds was previously known, but Dirlam wanted to discover the most efficient chunk size. The mathematical findings have discovered that four or three items in each chunk is the most optimal.
Channel capacity, "Magic number seven", increase of short-term memory
The word chunking comes from a famous 1956 paper by George A. Miller, "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information". At a time when information theory was beginning to be applied in psychology, Miller observed that some human cognitive tasks fit the model of a channel capacity characterized by a roughly constant capacity in bits, but short-term memory did not. A variety of studies could be summarized by saying that short-term memory had a capacity of about "seven plus-or-minus two" chunks. Miller wrote, "With binary items, the span is about nine and, although it drops to about five with monosyllabic English words, the difference is far less than the hypothesis of constant information would require (see also, memory span). The span of immediate memory seems to be almost independent of the number of bits per chunk, at least over the range that has been examined to date." Miller acknowledged that "we are not very definite about what constitutes a chunk of information."
Miller (1956) noted that according to this theory, it should be possible to increase short-term memory for low-information-content items effectively by mentally recoding them into a smaller number of high-information-content items. He imagined this process is useful in scenarios such as "a man just beginning to learn radio-telegraphic code hears each dit and dah as a separate chunk. Soon he is able to organize these sounds into letters and then he can deal with the letters as chunks. Then the letters organize themselves as words, which are still larger chunks, and he begins to hear whole phrases." Thus, a telegrapher can effectively "remember" several dozen dits and dahs as a single phrase. Naïve subjects can remember a maximum of only nine binary items, but Miller reports a 1954 experiment in which people were trained to listen to a string of binary digits and (in one case) mentally group them into groups of five, recode each group into a name (for example, "twenty-one" for 10101), and remember the names. With sufficient practice, people found it possible to remember as many as forty binary digits. Miller wrote:
Expertise and skilled memory effects Studies have shown that people have better memories when they are trying to remember items with which they are familiar. Similarly, people tend to create familiar chunks. This familiarity allows one to remember more individual pieces of content, and also more chunks as a whole. One well-known chunking study was conducted by Chase and Ericsson, who worked with an undergraduate student, SF, for over two years. They wanted to see if a person's digit span memory could be improved with practice. SF began the experiment with a normal span of seven digits. SF was a long-distance runner, and chunking strings of digits into race times increased his digit span. By the end of the experiment, his digit span had grown to 80 numbers. A later description of the research in The Brain-Targeted Teaching Model for 21st Century Schools states that SF later expanded his strategy by incorporating ages and years, but his chunks were always familiar, which allowed him to recall them more easily. Someone who does not have knowledge in the expert domain (e.g. being familiar with mile/marathon times) would have difficulty chunking with race times and ultimately be unable to memorize as many numbers using this method. The idea that a person who does not have knowledge in the expert domain would have difficulty chunking could also be seen in an experiment of novice and expert hikers to see if they could remember different mountain scenes. From this study, it was found that the expert hikers had better recall and recognition of structured stimuli. Another example could be seen with expert musicians in being able to chunk and recall encoded material that best meets the demands they are presented with at any given moment during the performance.
Chunking and memory in chess revisited
Previous research has shown that chunking is an effective tool for enhancing memory capacity due to the nature of grouping individual pieces into larger, more meaningful groups that are easier to remember. Chunking is a popular tool for people who play chess, specifically a master. Chase and Simon (1973a) discovered that the skill levels of chess players are attributed to long-term memory storage and the ability to copy and recollect thousands of chunks. The process helps acquire knowledge at a faster pace. Since it is an excellent tool for enhancing memory, a chess player who utilizes chunking has a higher chance of success. According to Chase and Simon, while re-examining (1973b), an expert chess master is able to access information in long-term memory storage quickly due to the ability to recall chunks. Chunks stored in long-term memory are related to the decision of the movement of board pieces due to obvious patterns.
Chunking models for education
Many years of research have concluded that chunking is a reliable process for gaining knowledge and organization of information. Chunking provides explanation to the behavior of experts, such as a teacher. A teacher can utilize chunking in their classroom as a way to teach the curriculum. Gobet (2005) proposed that teachers can use chunking as a method to segment the curriculum into natural components. A student learns better when focusing on key features of material, so it is important to create the segments to highlight the important information. By understanding the process of how an expert is formed, it is possible to find general mechanisms for learning that can be implemented into classrooms.
Chunking in motor learning