Editing Parallel processing (psychology) (section)

== Background ==
In 1990, American Psychologist [[David Rumelhart]] proposed the model of parallel distributed processing (PDP) in hopes of studying [[neural processes]] through [[computer simulation]]s.<ref name=":2">{{Cite journal |last1=Rogers |first1=Timothy T. |last2=McClelland |first2=James L. |date=December 2008 |title=Précis of Semantic Cognition: A Parallel Distributed Processing Approach |url=https://www.cambridge.org/core/product/identifier/S0140525X0800589X/type/journal_article |journal=Behavioral and Brain Sciences |language=en |volume=31 |issue=6 |pages=689–714 |doi=10.1017/S0140525X0800589X |s2cid=145402215 |issn=0140-525X}}</ref> According to Rumelhart, the PDP model represents information processing as interactions between elements called units, with the interactions being either excitatory or inhibitory in nature.<ref name=":3">{{Cite book |last=Rumelhart |first=David E. |url=https://www.worldcat.org/oclc/12837549 |title=Parallel distributed processing : explorations in the microstructure of cognition |date=1986 |publisher=MIT Press |others=James L. McClelland, San Diego. PDP Research Group University of California |isbn=0-262-18120-7 |location=Cambridge, Mass. |oclc=12837549}}</ref> Parallel Distributed Processing Models are neurally inspired, emulating the organisational structure of nervous systems of living organisms.<ref name=":02">{{Cite book|last1=Rumelhart|first1=David E. |title=Parallel distributed processing: explorations in the microstructure of cognition |date=1986 |publisher=MIT Press |first2=James L. |last2=McClelland |author3=PDP Research Group |isbn=0-262-18120-7|location=Cambridge, Mass. |oclc=12837549}}</ref> A general mathematical framework is provided for them.

Parallel processing models assume that information is represented in the brain using patterns of activation. Information processing encompasses the interactions of [[neuron]]-like units linked by [[synapse]]-like connections. These can be either [[Excitatory synapse|excitatory]] or [[Inhibitory postsynaptic potential|inhibitory]]. Every individual unit's activation level is updated using a [[Function (mathematics)|function]] of connection strengths and activation level of other units. A set of response units is activated by the propagation of activation patterns. The connection weights are eventually adjusted using learning.<ref>{{Cite journal|last=Holyoak|first=Keith J.|date=1987|editor-last=Rumelhart|editor-first=David E.|editor2-last=McClelland|editor2-first=James L.|editor3-last=Group|editor3-first=PDP Research|title=A Connectionist View of Cognition|url=https://www.jstor.org/stable/1699673|journal=Science|volume=236|issue=4804|pages=992–996|doi=10.1126/science.236.4804.992 |jstor=1699673 |pmid=17812774 |issn=0036-8075}}</ref>

=== Serial vs parallel processing ===
In contrast to parallel processing, serial processing involves sequential processing of information, without any overlap of processing times.<ref>{{Cite journal|last=Townsend|first=James T.|date=January 1990|title=Serial vs. Parallel Processing: Sometimes They Look like Tweedledum and Tweedledee but they can (and Should) be Distinguished|url=http://dx.doi.org/10.1111/j.1467-9280.1990.tb00067.x|journal=Psychological Science|volume=1|issue=1|pages=46–54|doi=10.1111/j.1467-9280.1990.tb00067.x|s2cid=51773777 |issn=0956-7976}}</ref> The distinction between these two processing models is most observed during visual stimuli is targeted and processed (also called visual search).

==== Visual search ====
In case of serial processing, the elements are searched one after the other in a serial order to find the target. When the target is found, the search terminates. Alternatively, it continues to the end to ensure that the target is not present. This results in reduced accuracy and increased time for displays with more objects.

On the other hand, in the case of parallel processing, all objects are processed simultaneously but the completion times may vary. This may or may not reduce the accuracy, but the time courses are similar irrespective of the size of the display.<ref>{{Cite journal|last1=Dosher|first1=Barbara Anne|last2=Han|first2=Songmei|last3=Lu|first3=Zhong-Lin|date=2010|title=Information-limited parallel processing in difficult heterogeneous covert visual search.|url=http://dx.doi.org/10.1037/a0020366|journal=Journal of Experimental Psychology: Human Perception and Performance|volume=36|issue=5|pages=1128–1144|doi=10.1037/a0020366|pmid=20873936 |pmc=3929106 |issn=1939-1277}}</ref>

However, there are concerns about the efficiency of parallel processing models in case of complex tasks which are discussed ahead in this article.