Chunking Definition

Cognitive  psychologists  argue  that  over  time, task-related  knowledge  is  organized  into  information-rich  representations  or  chunks,  a  process termed chunking. Dechunking refers to when well developed chunks are broken down into a number of smaller chunks or bits of information. Chunking is a fundamental building block of human memory and underlies the learning of perceptual and motor skills. Dechunking is a mechanism that potentially underlies  suboptimal  performance.  In  this  entry, the process by which information is chunked during  learning  is  explained  in  general  terms  and  in relation to both perceptual and motor skills. The process  and  implication  of  dechunking  are  then briefly discussed.

To  operate  effectively,  humans  must  utilize information in the performance environment, but the  human  information-processing  system  has limitations.  Specifically,  the  capacity  to  store  and retrieve  verbally  coded,  declarative  knowledge is  finite  and  small,  and  serial  processing  of  such information is time consuming. Despite these limitations,  people  can  successfully  execute  perceptual–motor  skills  in  environments  that  are  often complex,  dynamic,  and  time  constrained.  Indeed, experts  are  defined  by  their  ability  to  overcome the  limitations  of  the  information  processing  system.  Their  decisions  depend  upon  rapid  processing  of  large  quantities  of  perceptual  information. Their  motor  skills  are  executed  in  a  smooth  and automated  fashion.  Chunking  underlies  these capabilities.

Stage  models  of  skill  acquisition  propose  that early  in  learning  bits  of  information  pertaining to  a  task  are  stored,  retrieved,  and  processed  as declarative  knowledge  by  a  short-term  information  processor  (working  memory),  which  interfaces  with  long-term  memory.  With  repeated on-task   experience,   meaningful   associations emerge between recurring bits of information that are  grouped  together  and  coded  as  chunks.  Over the course of practice, between-chunk associations develop  and  higher  and  higher  level  chunks  are compiled, until large amounts of the information pertaining  to  a  task  are  hierarchically  organized into a single representative chunk. The demand on information  processing  resources  lessens  as  each level of the hierarchical structure is formed, until higher  level  chunks  take  a  procedural  form  that no longer requires the retrieval and processing of declarative knowledge. In the domain of sport and exercise,  chunking  takes  two  distinct  forms:  the chunking  of  perceptual  information  for  response selection, and the chunking of the motor information  needed  to  organize  and  execute  a  successful response.

The   strategies   and   rules   inherent   within dynamic activities like team sports generally result in  the  availability  of  structured  perceptual  information, such as the relative position of teammates and opponents or the mechanics of an opponent’s movements.  Visual  elements  that  meaningfully correlate  gradually  become  recognized  as  distinct  patterns.  With  increased  exposure,  relations between  these  patterns  emerge  and  so  they  are compiled  together,  and  from  then  on  recognized as a single pattern. Empirically, the chunking process has been demonstrated by findings that show experts  have  superior  capacity  to  recall  patterns of  game  play  after  only  a  brief  presentation  of  a structured,  rather  than  transitory,  unstructured game scenario. Chunking allows experts to quickly and accurately recognize patterns from within the unfolding  events  and  this,  in  turn,  permits  both the rapid and accurate selection of an appropriate motor response.

A motor response is the outcome of the ordered execution of a sequence of movement components. In the early stage of motor learning, the sequencing and control of independent movement components  is  typically  controlled  at  a  conscious  level, placing  high  demands  on  the  available  information  processing  resources.  Consistent  repetition of a pattern of movement through practice causes adjacent  movement  components  to  coalesce  into chunks. Chunks in motor learning are defined by pauses between successive movement components. For   example,   sequential   key   pressing   experiments  show  that  latencies  between  successive key  presses  decrease  with  practice  in  a  clear  and consistent fashion such that longer pauses demarcate  chunk  boundaries.  Pauses  between  adjacent motor chunks result in a segmented or jerky motor action.  Continued  practice  builds  a  hierarchical  structure,  in  which  fewer  chunks  comprising longer  sequences  of  movement  components  exist. As  a  result,  the  movement  is  both  less  jerky  and places  fewer  demands  on  information  processing resources.  Eventually,  all  movement  components are incorporated into a single representative motor chunk, which, when selected, results in the smooth, automatic  production  of  complex  sequences  of movement.

Compared   to   the   concept   of   chunking, dechunking  is  a  less  well  established  phenomenon. As chunking is associated with the learning or  progression  of  skills,  dechunking  may  be  used to  explain  occurrences  of  skill  regression  or  skill failure.  Declarative  knowledge  accrued  during learning likely remains retrievable from long-term memory  after  it  has  been  chunked  at  a  higher level.  The  retrieval  and  processing  of  previously chunked  declarative  knowledge  represents  the dechunking  of  optimal  and  automated  representations  and  regression  to  a  less  efficient  and  less fluid mode of control. In the competitive environment,  contingencies  such  as  performance  anxiety may trigger dechunking and result in skill failure. Alternatively, in the training environment athletes may  purposefully  attempt  to  revise  the  composition of high-level representations by first dechunking and then rechunking information.

In  summary,  the  chunking  of  information  is  a consequence  of  the  practice  that  underlies  skill learning.   It   allows   well-practiced   performers to  operate  proficiently  despite  the  temporal  and capacity  constraints  of  the  information  processing  system.  Dechunking  describes  a  return  to the  retrieval  and  processing  of  hitherto  chunked declarative knowledge.

References:

  1. Anderson, J. R. (1982). Acquisition of cognitive skill. Psychological Review, 89, 369–406.
  2. Gobet, F., & Simon, H. A. (1998). Expert chess memory: Revisiting the chunking hypothesis. Memory, 6, 225–255.
  3. Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81–97.
  4. Rosenbaum, D. A., Kenny, S. B., & Derr, M. A. (1983). Hierarchical control of rapid movement sequences. Journal of Experimental Psychology: Human Perception and Performance, 9, 86–102.

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