Editing Short-term memory (section)

== Capacity ==
Whatever the cause(s) of short-term forgetting, consensus asserts that it limits the amount of retained new information short term. This limit is referred to as the finite capacity of short-term memory. Short-term memory capacity is often called [[memory span]], in reference to a common measurement procedure. In a memory span test, the experimenter presents a list of items (e.g. digits or words) of increasing length. An individual's span is determined as the longest list length that he or she can recall correctly in the given order on half or more trials.

In an early and influential article, "[[The Magical Number Seven, Plus or Minus Two]]",<ref name="miller2">{{cite journal |last=Miller |first=G. A. |author-link=George Armitage Miller |year=1956 |title=The magical number seven, plus or minus two: Some limits on our capacity for processing information |journal=Psychological Review |volume=63 |issue=2 |pages=81–97 |citeseerx=10.1.1.308.8071 |doi=10.1037/h0043158 |pmid=13310704 |title-link=The Magical Number Seven, Plus or Minus Two|s2cid=15654531 }}</ref> [[George Armitage Miller|Miller]] suggested that human short-term memory has a forward memory span of approximately seven plus or minus two items and that that was well known at the time (apparently originating with Wundt). Later research reported that this "magical number seven" is roughly accurate for college students recalling lists of digits, but memory span varies widely across populations and material. For example, the ability to recall words in order depends on characteristics of those words: fewer words can be recalled when the words have longer spoken duration; this is known as the ''word-length effect'',<ref>Baddeley, Thomson & Buchanan, 1975</ref> or when their speech sounds are similar to each other; this is called the ''phonological similarity effect''.<ref>Conrad & Hull, 1964</ref> More words can be recalled when the words are highly familiar or occur frequently in speech.<ref>Poirier & Saint-Aubin, 1996</ref> Recall performance is better when all of the words are taken from a single semantic category (such as games) than when the words are chosen randomly.<ref>Poirier & Saint-Aubin, 1995</ref> A later estimate of short-term memory capacity reported that the capacity was about four pieces, or "chunks", of information.<ref>{{Cite journal |last1=Cowan |first1=N. |year=2001 |title=The magical number 4 in short-term memory: A reconsideration of mental storage capacity |journal=Behavioral and Brain Sciences |volume=24 |issue=1 |pages=97–185 |doi=10.1017/s0140525x01003922 |pmid=11515286 |doi-access=free}}</ref> Other notable theories argue against measuring capacity in terms of the number of elements.<ref name=":0">{{Cite journal |last1=Bays |first1=P. M. |last2=Husain |first2=M. |year=2008 |title=Dynamic shifts of limited working memory resources in human vision |journal=Science |volume=321 |issue=5890 |pages=851–854 |bibcode=2008Sci...321..851B |doi=10.1126/science.1158023 |pmc=2532743 |pmid=18687968}}</ref><ref name=":1">{{Cite journal |last1=Ma |first1=W. J. |last2=Husain |first2=M. |last3=Bays |first3=P. M. |year=2014 |title=Changing concepts of working memory |journal=Nature Neuroscience |volume=17 |issue=3 |pages=347–356 |doi=10.1038/nn.3655 |pmc=4159388 |pmid=24569831}}</ref><ref>Tarnow, (2010). There is no capacity limited buffer in the Murdock (1962) free recall data. ''Cognitive Neurodynamics''</ref>

In the visual domain, several studies report no fixed capacity limit in terms of total number of items that can be retained. Instead, some investigators have argued for a limited resource that can be flexibly shared between items held in short-term memory, with some items (in the focus of attention) being allocated more resource and being recalled with greater fidelity.<sup><ref name=":0" /><ref name=":1" /></sup> Many of these experiments have used delayed response tasks that have a continuous, analogue response space, rather than using a binary (correct/incorrect) recall method as is often used in change detection tasks. Instead of asking people to report whether a change occurred between the memory and probe array, delayed reproduction tasks require participants to reproduce the precise quality of a visual feature, e.g. an object's orientation or colour.<ref>{{cite journal |last1=Brady |first1=T. F. |last2=Konkle |first2=T. |last3=Alvarez |first3=G. A. |title=A review of visual memory capacity: Beyond individual items and toward structured representations |journal=Journal of Vision |date=26 May 2011 |volume=11 |issue=5 |pages=4 |doi=10.1167/11.5.4 |pmc=3405498 |pmid=21617025 }}</ref><ref>{{cite journal |last1=Bays |first1=P. M. |last2=Catalao |first2=R. F. G. |last3=Husain |first3=M. |title=The precision of visual working memory is set by allocation of a shared resource |journal=Journal of Vision |date=1 September 2009 |volume=9 |issue=10 |pages=7.1–11 |doi=10.1167/9.10.7 |pmc=3118422 |pmid=19810788 }}</ref><ref>{{cite journal |last1=Bays |first1=P. M. |last2=Gorgoraptis |first2=N. |last3=Wee |first3=N. |last4=Marshall |first4=L. |last5=Husain |first5=M. |title=Temporal dynamics of encoding, storage, and reallocation of visual working memory |journal=Journal of Vision |date=12 September 2011 |volume=11 |issue=10 |pages=6 |doi=10.1167/11.10.6 |pmc=3401684 |pmid=21911739 }}</ref>

=== Rehearsal ===
Rehearsal is the process of repeating information to be retained, ostensibly keeping it in short-term memory. Each repetition reenters the information into short-term memory, thus keeping that information for another 10 to 20 seconds (the average storage time for short-term memory).<ref>{{cite book |author=R. D. Campbell, Michael Bagshaw |title=Human Performance and Limitations in Aviation |publisher=John Wiley & Sons, 2008 |page=107 |chapter=Human Information Processing}}</ref>
This process allows information to be stored in the memory avoiding distracting stimuli, rehearsal allows new information to be strengthened which results in a likelihood of this information being stored in the long-term memory <ref>Plaska, C. R., Ng, K., & Ellmore, T. M. (2021). Does rehearsal matter? Left anterior temporal alpha and theta band changes correlate with the beneficial effects of rehearsal on working memory. Neuropsychologia, 155, 107825. https://doi.org/10.1016/j.neuropsychologia.2021.107825</ref>
However, the success of rehearsal can depend on factors such as attention as well as any form of distraction that is present because of this active rehearsal is essential to store that new information.

=== Chunking ===
[[Chunking (psychology)|Chunking]] is a technique that allows memory to remember more things. Chunking involves organizing material into meaningful groups. Chunking can greatly increase recall capacity. For example, in recalling a phone number, chunking the digits into three groups (area code, prefix, and extension). This method of remembering phone numbers is far more effective than attempting to remember a string of 10 digits.

Practice and the usage of existing information in long-term memory can lead to additional improvements in chunking. In one testing session, an American cross-country runner was able to recall a string of 79 digits after hearing them only once by chunking them into groups the size of a running time.<ref>Ericsson, Chase & Faloon, 1980</ref>

=== Factors ===
Diseases that cause neurodegeneration, such as [[Alzheimer's disease]], can damage short-term as well as long-term memory.<ref name="Zokaei 41–50">{{Cite journal |last1=Zokaei |first1=Nahid |last2=Sillence |first2=Annie |last3=Kienast |first3=Annika |last4=Drew |first4=Daniel |last5=Plant |first5=Olivia |last6=Slavkova |first6=Ellie |last7=Manohar |first7=Sanjay G. |last8=Husain |first8=Masud |date=November 2020 |title=Different patterns of short-term memory deficit in Alzheimer's disease, Parkinson's disease and subjective cognitive impairment |journal=Cortex |volume=132 |pages=41–50 |doi=10.1016/j.cortex.2020.06.016 |pmc=7651994 |pmid=32919108 }}</ref> Damage to certain sections{{which|date=January 2015}} of the brain due to this disease causes a shrinkage in the cerebral cortex, which impairs the ability to think and recall.<ref>{{Cite book |last1=Moscou |first1=Kathy |title=Pharmacology for Pharmacy Technicians |last2=Snipe |first2=Karen |publisher=Mosby Elsevier |year=2009 |isbn=978-0-323-04720-3 |pages=165–167}}</ref>

Short-term memory performance is influenced by diet. More intake of blueberries was reported to improve short-term memory after continuous use whereas alcohol decreases short-term memory performance.<ref>{{Cite journal |last=Gómez-Pinilla |first=Fernando |date=July 2008 |title=Brain foods: the effects of nutrients on brain function |journal=Nature Reviews. Neuroscience |volume=9 |issue=7 |pages=568–578 |doi=10.1038/nrn2421 |pmc=2805706 |pmid=18568016 }}</ref>