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== Working memory ==
Models of working memory primarily focused on declarative until Oberauer suggested that declarative and procedural memory may be processed differently in working memory.<ref>{{Cite book|chapter-url=http://linkinghub.elsevier.com/retrieve/pii/S007974210951002X|last=Oberauer|first=Klaus|pages=45–100|doi=10.1016/s0079-7421(09)51002-x|title=The Psychology of Learning and Motivation|volume=51|year=2009|isbn=9780123744890|chapter=Chapter 2 Design for a Working Memory|url=https://www.zora.uzh.ch/id/eprint/28472/1/Oberauer_PLM_2009.pdf}}</ref> The working memory model is thought to be divided into two subcomponents; one is responsible for declarative, while the other represents procedural memory.<ref>{{Cite journal|last=Oberauer|first=Klaus|last2=Souza|first2=Alessandra S.|last3=Druey|first3=Michel D.|last4=Gade|first4=Miriam|title=Analogous mechanisms of selection and updating in declarative and procedural working memory: Experiments and a computational model|journal=Cognitive Psychology|volume=66|issue=2|pages=157–211|doi=10.1016/j.cogpsych.2012.11.001|pmid=23276689|year=2013|url=https://www.semanticscholar.org/paper/8e793c2e35ed77d166cd4b3f0556304e26d09f62}}</ref><ref>{{Cite journal|last=Souza|first=Alessandra da Silva|last2=Oberauer|first2=Klaus|last3=Gade|first3=Miriam|last4=Druey|first4=Michel D.|date=2012-05-01|title=Processing of representations in declarative and procedural working memory|journal=The Quarterly Journal of Experimental Psychology|volume=65|issue=5|pages=1006–1033|doi=10.1080/17470218.2011.640403|issn=1747-0218|pmid=22332900}}</ref> These two subsections are considered to be largely independent of each other.<ref>{{Cite journal|last=Gade|first=Miriam|last2=Druey|first2=Michel D.|last3=Souza|first3=Alessandra S.|last4=Oberauer|first4=Klaus|title=Interference within and between declarative and procedural representations in working memory|journal=Journal of Memory and Language|volume=76|pages=174–194|doi=10.1016/j.jml.2014.07.002|year=2014}}</ref> It has also been determined that the process for selection may be very similar in nature when considering either modality of working memory .<ref>{{Cite journal|last=Gade|first=Miriam|last2=Souza|first2=Alessandra S.|last3=Druey|first3=Michel D.|last4=Oberauer|first4=Klaus|date=2017-01-01|title=Analogous selection processes in declarative and procedural working memory: N-2 list-repetition and task-repetition costs|journal=Memory & Cognition|language=en|volume=45|issue=1|pages=26–39|doi=10.3758/s13421-016-0645-4|pmid=27517876|issn=0090-502X|doi-access=free}}</ref>
 
==Acquisition of skill==
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A device used to study visual-motor tracking skills and [[hand–eye coordination]] by requiring the participant to follow a moving object with a [[cursor (computers)|cursor]]<ref name="Cognitive Atlas">{{Cite web | url=http://www.cognitiveatlas.org | title=Cognitive Atlas}}</ref> or use a [[stylus]] to follow the target on a computer screen or a turntable.<ref>{{cite web |url=http://149.142.158.188/phenowiki/wiki/index.php/Pursuit_Rotor_Task |title=Archived copy |accessdate=2012-02-27 |url-status=dead |archiveurl=https://web.archive.org/web/20130927220537/http://149.142.158.188/phenowiki/wiki/index.php/Pursuit_Rotor_Task |archivedate=27 September 2013 |df=dmy-all }}</ref> With the computer screen version, the participant follows a dot on a circular path like the one shown below.<ref>{{Cite web | url=http://peblblog.blogspot.com/2010/04/pursuit-rotor-task.html | title=PEBL Blog: The Pursuit Rotor Task| date=2010-04-24}}</ref> [[File:PursuitRotor.png|thumb|Screenshot of a computerized version of the pursuit rotor task.]]
 
The pursuit rotor task is a simple pure visual-motor tracking test that has consistent results within age groups.<ref name="Lang">{{cite journal | url = | doi=10.1016/0191-8869(81)90025-8 | volume=2 | issue=3 | title=Learning and reminiscence in the pursuit rotor performance of normal and depressed subjects | journal=Personality and Individual Differences | pages=207–213 | year=1981 | last1 = Lang | first1 = Rudie J.}}</ref> This displays a measurement of procedural memory as well as demonstrates the participant's [[fine motor skill]]s. The pursuit rotor task tests the fine-motor skills which are controlled by the motor cortex illustrated by the green section below. [[File:Cerebral lobes.png|thumb]]<ref name="Allen">{{cite journal | last1 = Allen | first1 = J.S. | last2 = Anderson | first2 = S.W. | last3 = Castro-Caldas | first3 = A. | last4 = Cavaco | first4 = S. | last5 = Damasio | first5 = H. | year = 2004 | title = The scope of preserved procedural memory in amnesia | url = | journal = Brain | volume = 127 | issue = 8| pages = 1853–67 | doi = 10.1093/brain/awh208 | pmid = 15215216 | doi-access = free }}</ref> The results are then calculated by the participant's time-on and time-off the object. Amnesic participants show no impairment in this motor task when tested at later trials. It does however seem to be affected by lack of sleep and drug use.<ref name="Dotto">{{cite journal | last1 = Dotto | first1 = L | year = 1996 | title = Sleep Stages, Memory and Learning | url = | journal = Canadian Medical Association | volume = 154 | issue = 8| pages = 1193–6 | pmid = 8612256 | pmc = 1487644 }}</ref>
 
===Serial reaction time task===
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== Genetic influence ==
Genetic makeup has been found to impact skill learning and performance, and therefore plays a role in achieving expertise. Using the pursuit rotor task, one study examined the effects of [[Practice (learning method)|practice]] in identical and fraternal twins raised in separate homes. Because identical twins share 100% of their genes while fraternal twins share 50%, the impact of genetic makeup on skill learning could be examined. The results of the pursuit rotor task test became more identical with practice over time for the identical twins, whereas the results for the fraternal twins became more disparate with practice. In other words, the performance of the skill by the identical twins became closer to 100% identical, while the fraternal twins' skill performance became less identical, suggesting the 50% difference in genetic makeup is responsible for the difference in skill performance. The study shows that more practice leads to a closer representation of a person's innate capability, also known as [[Aptitude|talent]]. Therefore, some of the differences people show after extended practice increasingly reflects their genetics. The study also confirmed the idea that practice improves skill learning by showing that, in both the identical and fraternal groups, more practice aided in shedding ineffective tendencies in order to improve execution of a given skill.<ref>{{Cite journal|last=Fox|first=Paul W.|last2=Hershberger|first2=Scott L.|last3=Bouchard|first3=Thomas J.|date=1996-11-28|title=Genetic and environmental contributions to the acquisition of a motor skill|journal=Nature|language=en|volume=384|issue=6607|pages=356–358|doi=10.1038/384356a0|pmid=8934520|bibcode=1996Natur.384..356F|url=https://www.semanticscholar.org/paper/afa191e4026af47dbe915c19349046eba4c4c1e3}}</ref><ref>{{Cite book|title=Learning and memory : from brain to behavior|last=Eduardo.|first=Mercado|last2=E.|first2=Myers, Catherine|date=2014-01-01|publisher=Worth Publishers|isbn=9781429240147|___location=|pages=307–308|oclc=900627172}}</ref> Currently, the link between [[learning]] and genetics has been limited to simple task learning, while a link to more complex forms of learning, such as the learning of [[cognitive skill]]s, has not been confirmed.<ref>{{Cite journal|last=Wulf|first=Gabriele|last2=Shea|first2=Charles H.|date=2002-06-01|title=Principles derived from the study of simple skills do not generalize to complex skill learning|journal=Psychonomic Bulletin & Review|language=en|volume=9|issue=2|pages=185–211|doi=10.3758/BF03196276|pmid=12120783|issn=1069-9384|doi-access=free}}</ref>
 
==Anatomical structures==
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{{details|topic=the basal ganglia|Basal ganglia}}
[[File:Basal ganglia and related structures (2).svg|thumb|right|Basal ganglia (red) and related structures (blue) shown within the brain]]
The [[dorsolateral]] striatum is associated with the acquisition of habits and is the main neuronal cell nucleus linked to procedural memory. Connecting excitatory [[afferent nerve fiber]]s help in the regulation of activity in the basal ganglia circuit. Essentially, two parallel information processing pathways diverge from the striatum. Both acting in opposition to each other in the control of movement, they allow for association with other needed functional structures<ref>{{cite journal | last1 = Alexander | first1 = GE | last2 = Crutcher | first2 = MD | year = 1990 | title = Functional architecture of basal ganglia circuits; neural substrates of parallel processing | url = | journal = Trends Neurosci | volume = 13 | issue = 7| pages = 266–271 | doi=10.1016/0166-2236(90)90107-l | pmid=1695401}}</ref> One pathway is direct while the other is indirect and all pathways work together to allow for a functional neural feedback loop. Many looping circuits connect back at the striatum from other areas of the brain; including those from the emotion-center linked limbic cortex, the reward-center linked [[ventral striatum]] and other important motor regions related to movement.<ref>{{cite journal | last1 = Haber | first1 = SN | last2 = Fudge | first2 = JL | last3 = McFarland | first3 = NR | year = 2000 | title = Striatonigrostriatal pathways in primates form an ascending spiral from the shell to the dorsolateral striatum | url = | journal = J. Neurosci. | volume = 20 | issue = 6| pages = 2369–2382 | doi = 10.1523/JNEUROSCI.20-06-02369.2000 | doi-access = free }}</ref> The main looping circuit involved in the motor skill part of procedural memory is usually called the cortex-basal ganglia-thalamus-cortex loop.<ref>{{cite journal | last1 = Parent | first1 = A | year = 1990 | title = Extrinsic connections of the basal ganglia | url = | journal = Trends Neurosci | volume = 13 | issue = 7| pages = 254–258 | doi=10.1016/0166-2236(90)90105-j| pmid = 1695399 }}</ref>
 
The striatum is unique because it lacks the [[glutamate]]-related neurons found throughout most of the brain. Instead, it is categorized by a high concentration of a special type of [[GABA]] related inhibiting cell known as the [[medium spiny neuron]].<ref>{{cite journal | last1 = Smith | first1 = Y. | last2 = Raju | first2 = D. V. | last3 = Pare | first3 = J. F. | last4 = Sidibe | first4 = M. | year = 2004 | title = The thalamostriatal system: a highly specific network of the basal ganglia circuitry | url = https://www.semanticscholar.org/paper/99588f5770f5388d0c260eb6b70b9c88ebff0171| journal = Trends Neurosci | volume = 27 | issue = 9| pages = 520–527 | doi=10.1016/j.tins.2004.07.004| pmid = 15331233 }}</ref> The two parallel pathways previously mentioned travel to and from the striatum and are made up of these same special medium spiny neurons. These neurons are all sensitive to different neurotransmitters and contain a variety of corresponding receptors including dopamine receptors ([[DRD1]], [[DRD2]]), [[muscarinic receptors]] (M4) and [[adenosine receptors]] (A2A). Separate interneurons are known to communicate with striatal spiny neurons in the presence of the [[somatic nervous system]] neurotransmitter [[acetylcholine]].<ref>{{cite journal | last1 = Zhou | first1 = FM | last2 = Wilson | first2 = CJ | last3 = Dani | first3 = JA | year = 2002 | title = Cholinergic Interneuron characteristics and nicotinic properties in the striatum | url = | journal = J. Neurobiol. | volume = 53 | issue = 4| pages = 590–605 | doi=10.1002/neu.10150 | pmid=12436423}}</ref>
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===Parkinson's disease===
{{details|topic=Parkinson's disease|Parkinson's disease}}
[[Parkinson's disease]] is known to affect selective areas in the frontal lobe area of the brain. Current scientific information suggests that the memory performance problems notably shown in patients are controlled by unusual frontostriatal circuits.<ref>{{cite journal | last1 = Sarazin | first1 = M | last2 = Deweer | first2 = B | last3 = Pillon | first3 = B | last4 = Merkl | first4 = A | last5 = Dubois | first5 = B | date = Dec 2001 | title = Procedural learning and Parkinson disease: implication of striato-frontal loops | url = | journal = Rev Neurol | volume = 157 | issue = 12| pages = 1513–8 | pmid = 11924447 }}</ref> Parkinson's patients often have difficulty with the sequence-specific knowledge that is needed in the acquisition step of procedural memory.<ref>{{cite journal | last1 = Muslimovic | first1 = D | last2 = Post | first2 = B | last3 = Speelman | first3 = JD | last4 = Schmand | first4 = B | date = Nov 2007 | title = Motor procedural learning in Parkinson's disease | url = | journal = Brain | volume = 130 | issue = 11| pages = 2887–97 | doi=10.1093/brain/awm211| pmid = 17855374 | doi-access = free }}</ref> Further evidence suggests that the frontal lobe networks relate to executive function and only act when specific tasks are presented to the patient. This tells us that the frontostriatal circuits are independent but able to work collaboratively with other areas of the brain to help with various things such as paying attention or focusing.<ref>{{cite journal | last1 = Sarazin | first1 = M | last2 = Deweer | first2 = B | last3 = Merkl | first3 = A | last4 = Von Poser | first4 = N | last5 = Pillon | first5 = B | last6 = Dubois | first6 = B | date = Mar 2002 | title = Procedural learning and striatofrontal dysfunction in Parkinson's disease | url = | journal = Mov Disord | volume = 17 | issue = 2| pages = 265–73 | doi=10.1002/mds.10018| pmid = 11921111 }}</ref>
 
===Schizophrenia===
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{{details|topic=psychostimulants|Psychostimulant}}
Most [[psychostimulant]]s work by activating dopamine receptors causing increased focus or pleasure. The usage of psychostimulants has become more widespread in the medical world for treating conditions like [[ADHD]]. Psychostimulants have been shown to be used more frequently today amongst students and other social demographics as a means to study more efficiently or have been abused for their pleasurable side effects.<ref>McCabe, S. E., Knight, J. R., Teter, C. J., Wechsler, H. (2004). Non-medical use of prescription stimulants among US
college students: prevalence and correlates from anational survey. Research Report.</ref> Research suggests that when not abused, psychostimulants aid in the acquisition of procedural learning. Studies have shown that psychostimulants like [[d-amphetamine]] facilitates lower response times and increased procedural learning when compared to control participants and participants who have been administered the [[antipsychotics|antipsychotic]] [[haloperidol]] on procedural learning tasks.<ref>Kumari, V., Gray, J.A., Corr, P.J., Mulligan, O.F., Cotter, P.A., Checkley, S.A. (1997). Effects of acute administration of d-amphetamine and haloperidol on procedural learning in man. ''Journal of Psychopharmacology'' 129(3); 271–276</ref> While improvements in procedural memory were evident when participants were administered traces of psychostimulants, many researchers have found that procedural memory is hampered when psychostimulants are abused.<ref>{{cite journal | last1 = Toomey | first1 = R. | last2 = Lyons | first2 = M. J. | last3 = Eisen | first3 = S. A. | last4 = Xian | first4 = Hong | last5 = Chantarujikapong | first5 = Sunanta | last6 = Seidman | first6 = L. J. | last7 = Faraone | first7 = S. | last8 = Tsuang | first8 = M. T. | year = 2003 | title = A Twin Study of the Neuropsychological Consequences of Stimulant Abuse | url = | journal = Arch Gen Psychiatry | volume = 60 | issue = 3| pages = 303–310 | doi=10.1001/archpsyc.60.3.303| pmid = 12622664 | doi-access = free }}</ref> This introduces the idea that for optimal procedural learning, dopamine levels must be balanced.
 
==Sleep==
Practice is clearly an important process for learning and perfecting a new skill. With over 40 years of research, it is well established in both humans and animals that the formation of all forms of memory are greatly enhanced during the brain-state of sleep. Furthermore, with humans, sleep has been consistently shown to aid in the development of procedural knowledge by the ongoing process of memory consolidation, especially when sleep soon follows the initial phase of memory acquisition.<ref>{{cite journal | last1 = Karni | first1 = A. | last2 = Tanne | first2 = D. | last3 = Rubenstein | first3 = B.S. | last4 = Askenasy | first4 = J.J. | last5 = Sagi | first5 = D. | year = 1994 | title = Dependence on REM sleep of overnight improvement of a perceptual skill | url = | journal = Science | volume = 265 | issue = 5172| pages = 679–682 | doi=10.1126/science.8036518| pmid = 8036518 | bibcode = 1994Sci...265..679K }}</ref><ref>{{cite journal | last1 = Gais | first1 = S. | last2 = Plihal | first2 = W. | last3 = Wagner | first3 = U. | last4 = Born | first4 = J. | year = 2000 | title = Early sleep triggers memory for early visual discrimination skills | url = https://www.semanticscholar.org/paper/ba7d00d764e18b32c63b0eae5a5edf9854b09c28| journal = Nat. Neurosci. | volume = 3 | issue = 12| pages = 1335–1339 | doi=10.1038/81881| pmid = 11100156 }}</ref><ref>{{cite journal | last1 = Stickgold | first1 = R. | last2 = James | first2 = L. | last3 = Hobson | first3 = J.A. | year = 2000a | title = Visual discrimination learning requires sleep after training | url = | journal = Nat. Neurosci. | volume = 3 | issue = 12| pages = 1237–1238 | doi=10.1038/81756| pmid = 11100141 | doi-access = free }}</ref><ref>{{cite journal | last1 = Stickgold | first1 = R. | last2 = Whidbee | first2 = D. | last3 = Schirmer | first3 = B. | last4 = Patel | first4 = V. | last5 = Hobson | first5 = J.A. | year = 2000b | title = Visual discrimination task improvement: A multi-step process occurring during sleep | url = https://www.semanticscholar.org/paper/f635eb5e63eff7dc17c1b0b9548f80b1b35b76cf| journal = J. Cogn. Neurosci. | volume = 12 | issue = 2| pages = 246–254 | doi=10.1162/089892900562075| pmid = 10771409 }}</ref><ref>{{cite journal | last1 = Walker | first1 = M.P. | last2 = Brakefield | first2 = T. | last3 = Morgan | first3 = A. | last4 = Hobson | first4 = J.A. | last5 = Stickgold | first5 = R. | year = 2002 | title = Practice with sleep makes perfect: Sleep dependent motor skill learning | url = | journal = Neuron | volume = 35 | issue = 1| pages = 205–211 | doi=10.1016/s0896-6273(02)00746-8 | pmid=12123620}}</ref> Memory consolidation is a process that transforms novel memories from a relatively fragile state to a more robust and stable condition. For a long time it was believed that the consolidation of procedural memories took place solely as a function of time,<ref>{{cite journal | last1 = Brashers-Krug | first1 = T. | last2 = Shadmehr | first2 = R. | last3 = Bizzi | first3 = E. | year = 1996 | title = Consolidation in human motor memory | url = | journal = Nature | volume = 382 | issue = 6588| pages = 252–255 | doi=10.1038/382252a0| pmid = 8717039 | citeseerx = 10.1.1.39.3383 | bibcode = 1996Natur.382..252B }}</ref><ref>{{cite journal | last1 = McGaugh | first1 = J.L. | year = 2000 | title = Memory—A century of consolidation | url = https://semanticscholar.org/paper/4599cc62e637a5619b3f9ee8dd2326d7288cbb1c| journal = Science | volume = 287 | issue = 5451| pages = 248–251 | doi=10.1126/science.287.5451.248 | pmid=10634773| bibcode = 2000Sci...287..248M }}</ref> but more recent studies suggest, that for certain forms of learning, the consolidation process is exclusively enhanced during periods of sleep.<ref>{{cite journal | last1 = Fischer | first1 = S. | last2 = Hallschmid | first2 = M. | last3 = Elsner | first3 = A.L. | last4 = Born | first4 = J. | year = 2002 | title = Sleep forms memory for finger skills | url = | journal = Proc. Natl. Acad. Sci. USA | volume = 99 | issue = 18| pages = 11987–11991 | doi=10.1073/pnas.182178199| pmid = 12193650 | pmc = 129381 | bibcode = 2002PNAS...9911987F }}</ref> However, it is important to note that not just any type of sleep is sufficient to improve procedural memory and performance on subsequent procedural tasks. In fact, within the ___domain of motor skill, there is evidence showing that no improvement on tasks is shown following a short, [[non-rapid eye movement]] (NREM; stages 2–4) sleep, such as a nap.<ref>{{cite journal | last1 = Siegel | first1 = J. M. | year = 2001 | title = The REM sleep-memory consolidation hypothesis | url = | journal = Science | volume = 294 | issue = 5544| pages = 1058–1063 | doi=10.1126/science.1063049| pmid = 11691984 | bibcode = 2001Sci...294.1058S }}</ref> [[REM sleep]] following a period of [[slow-wave sleep]] (SWS; combined stage 3 and 4 and the deepest form of NREM sleep), has shown to be the most beneficial type of sleep for procedural memory enhancement, especially when it takes place immediately after the initial acquisition of a skill. So essentially, a full night (or day) of uninterrupted sleep soon after learning a skill will allow for the most memory consolidation possible. Furthermore, if REM sleep is disrupted, there is no gain in procedural performance shown.<ref>{{cite journal | last1 = Karni | first1 = A. | last2 = Meyer | first2 = G. | last3 = Rey-Hipolito | first3 = C. | last4 = Jezzard | first4 = P. | last5 = Adams | first5 = M.M. | last6 = Turner | first6 = R. | last7 = Ungerleider | first7 = L.G. | year = 1998 | title = The acquisition of skilled motor performance: Fast and slow experience-driven changes in primarymotor cortex | url = | journal = Proc. Natl. Acad. Sci. USA | volume = 95 | issue = 3| pages = 861–868 | doi=10.1073/pnas.95.3.861| pmid = 9448252 | pmc = 33809 | bibcode = 1998PNAS...95..861K }}</ref> However, equal improvement will take place whether the sleep after practice was at night or during the daytime, as long as SWS is followed by REM sleep. It has also been shown that the enhancement in memory is specific to the learned stimulus (i.e., learning a running technique will not cross over to improvements in biking performance).<ref>{{cite journal | last1 = Mednick | first1 = S.C. | display-authors = etal | year = 2003 | title = Sleep-dependent learning: a nap is as good as a night | url = https://www.semanticscholar.org/paper/ee698a6866fc21686c4e6798f0c3dbc13e568d2d| journal = Nat. Neurosci. | volume = 6 | issue = 7| pages = 697–698 | doi=10.1038/nn1078 | pmid=12819785}}</ref> Subject performance in the Wff 'n Proof Task,<ref>Smith C. REM sleep and learning: some recent findings. In: Moffit A, Kramer M, Hoffman H, editors. The functions of dreaming. Albany:SUNY; 1993.</ref><ref>{{cite journal | last1 = Smith | first1 = C | last2 = Fazekas | first2 = A | year = 1997 | title = Amount of REM sleep and Stage 2 sleep required for efficient learning | url = | journal = Sleep Res | volume = 26 | issue = | page = 690 }}</ref><ref>{{cite journal | last1 = Smith | first1 = C | last2 = Weeden | first2 = K | year = 1990 | title = Post training REMs coincident auditory stimulation enhances memory in humans | url = | journal = Psychiatr J Univ Ott | volume = 15 | issue = 2| pages = 85–90 | pmid = 2374793 }}</ref> the [[Tower of Hanoi]],<ref>{{cite journal | last1 = Smith | first1 = CT | last2 = Nixon | first2 = MR | last3 = Nader | first3 = RS | year = 2004 | title = Post training increases in REM sleep intensity implicate REM sleep in memory processing and provide a biological marker of learning potential | url = | journal = Learn Mem | volume = 11 | issue = 6| pages = 714–9 | doi=10.1101/lm.74904| pmid = 15576889 | pmc = 534700 }}</ref> and the Mirror Tracing Task<ref>Conway J, Smith C. REM sleep and learning in humans: a sensitivity to specific types of learning tasks. In: Proceedings of the 12th Congress of the European Sleep Research Society. 1994.</ref> has been found to improve following REM sleep periods.
 
Whether a skill is learned explicitly (with [[attention]]) or implicitly, each plays a role in the offline consolidation effect. Research suggests that explicit awareness and understanding of the skill being learned during the acquisition process greatly improves the consolidation of procedural memories during sleep.<ref>{{cite journal | last1 = Robertson | first1 = E.M. | display-authors = etal | year = 2004 | title = Awareness modifies skill-learning benefits of sleep | url = | journal = Curr. Biol. | volume = 14 | issue = 3| pages = 208–212 | doi=10.1016/s0960-9822(04)00039-9| doi-access = free }}</ref> This finding is not surprising, as it is widely accepted that intention and awareness at time of learning enhances the acquisition of most forms of memory.
 
==Language==