Ensemble coding: Difference between revisions

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==Theory==

Extensive amounts of information are available to the [[visual system]]. Ensemble coding is a theory that suggests that people process the general gist of their complex visual surroundings by grouping objects together based on shared properties. The world is filled with redundant information of which the human [[visual system]] has become particularly sensitive.<ref name="Whitney_2014" /><ref>{{cite book | vauthors = Whitney D, Haberman J, Sweeny T | date = 2014 | chapter = From textures to crowds: multiple levels of summary statistical perception. | title = In The New Visual Neuroscience | veditors = Werner JS, Chalupa LM | pages = 695–710 | ___location = Cambridge, MA | publisher = MIT Press }}</ref> The brain exploits this redundancy and condenses the information. For example, the leaves of a tree or blades of grass give rise to the percept of 'tree-ness' and 'lawn-ness'.<ref name="Haberman_2012">{{cite book |last=Haberman |first=Jason |last2=Whitney |first2=David| name-list-format = vanc | chapter = Ensemble Perception |date = May 2012 | chapter-url = http://www.oxfordscholarship.com/view/10.1093/acprof:osobl/9780199734337.001.0001/acprof-9780199734337-chapter-30 | title = From Perception to Consciousness |pages=339–349 |editor-last=Wolfe |editor-first=Jeremy |editor2-last=Robertson |editor2-first=Lynn |publisher=Oxford University Press |doi=10.1093/acprof:osobl/9780199734337.003.0030 |isbn=978-0-19-973433-7|access-date=2019-12-09}}</ref> It has been demonstrated that individuals have the ability quickly and accurately encode ensembles of objects, like leaves on a tree, and gather summary statistical information (like the mean and variance) from groups of stimuli.<ref name=":5">{{cite journal| vauthors = Alt NP, Goodale B, Lick DJ, Johnson KL |date= March 2019 |title=Threat in the Company of Men: Ensemble Perception and Threat Evaluations of Groups Varying in Sex Ratio|journal=Social Psychological and Personality Science|volume=10 |issue=2 |pages=152–159 |doi=10.1177/1948550617731498 }}</ref><ref>{{cite journal | vauthors = Alvarez GA | title = Representing multiple objects as an ensemble enhances visual cognition | language = en-US | journal = Trends in Cognitive Sciences | volume = 15 | issue = 3 | pages = 122–31 | date = March 2011 | pmid = 21292539 | doi = 10.1016/j.tics.2011.01.003 | url = https://dash.harvard.edu/handle/1/41364280 }}</ref> Some research suggests that this process provides rough visual information from the entire [[visual field]] giving way to a complete and accurate picture of the visual world.<ref>{{cite journal | vauthors = Chong SC, Treisman A | title = Representation of statistical properties | journal = Vision Research | volume = 43 | issue = 4 | pages = 393–404 | date = February 2003 | pmid = 12535996 | doi = 10.1016/S0042-6989(02)00596-5 | url = https://linkinghub.elsevier.com/retrieve/pii/S0042698902005965 }}</ref><ref name="Seeing the mean: ensemble coding fo">{{cite journal | vauthors = Haberman J, Whitney D | title = Seeing the mean: ensemble coding for sets of faces | journal = Journal of Experimental Psychology. Human Perception and Performance | volume = 35 | issue = 3 | pages = 718–34 | date = June 2009 | pmid = 19485687 | pmc = 2696629 | doi = 10.1037/a0013899 }}</ref> Although the individual details of this accurate picture might be inaccessible, the 'gist' of the scene remains accessible.<ref name="Haberman_2012" /> Ensemble coding is an adaptive process that lightens the [[cognitive load]] in the processing and storing of visual representations through the use of [[heuristic]]s.<ref name="Seeing the mean: ensemble coding fo"/><ref name="Wolfe_2011">{{cite book |url= https://books.google.com/?id=Kw9pAgAAQBAJ&pg=PA339 |title=From Perception to Consciousness: Searching with Anne Treisman |last=Wolfe |first=Jeremy |last2=Robertson |first2=Lynn | name-list-format = vanc |date= December 2011 |publisher=Oxford University Press |isbn=978-0-19-990984-1|language=en}}</ref>

== Operational definition ==

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=== Limited visual capacity ===

[[Vision science]] has noted that although humans take in large amounts of visual information, adults are only able to process, attend to, and hold in memory up to roughly four items from the visual environment.<ref>{{cite journal | vauthors = Alvarez GA, Cavanagh P | title = The capacity of visual short-term memory is set both by visual information load and by number of objects | language = en-US | journal = Psychological Science | volume = 15 | issue = 2 | pages = 106–11 | date = February 2004 | pmid = 14738517 | doi = 10.1111/j.0963-7214.2004.01502006.x | url = http://nrs.harvard.edu/urn-3:HUL.InstRepos:41302706 }}</ref><ref name="Luck_1998">{{cite journal | vauthors = Luck SJ, Vogel EK | title = The capacity of visual working memory for features and conjunctions | journal = Nature | volume = 390 | issue = 6657 | pages = 279–81 | date = November 1997 | pmid = 9384378 | doi = 10.1038/36846 | bibcode = 1997Natur.390..279L }}</ref> Furthermore, scientists have found that this visual upper limit capacity exists across various phenomena including [[change blindness]],<ref>{{cite journal |last=O'Regan |first=J. Kevin |last2=Deubel |first2=Heiner |last3=Clark |first3=James J. |last4=Rensink |first4=Ronald A. | name-list-format = vanc |date=2000-01-01|title=Picture Changes During Blinks: Looking Without Seeing and Seeing Without Looking|journal=Visual Cognition|volume=7|issue=1–3|pages=191–211|doi=10.1080/135062800394766|issn=1350-6285}}</ref><ref>{{cite journal | vauthors = Simons DJ, Chabris CF | title = Gorillas in our midst: sustained inattentional blindness for dynamic events | journal = Perception | volume = 28 | issue = 9 | pages = 1059–74 | date = 1999-09-01 | pmid = 10694957 | doi = 10.1068/p281059 | url = https://semanticscholar.org/paper/44886a79b858115854c6c949c3799c2148016b75 }}</ref> [[object tracking]],<ref name="Scholl_1999">{{cite journal | vauthors = Scholl BJ, Pylyshyn ZW | title = Tracking multiple items through occlusion: clues to visual objecthood | journal = Cognitive Psychology | volume = 38 | issue = 2 | pages = 259–90 | date = March 1999 | pmid = 10090804 | doi = 10.1006/cogp.1998.0698 | url = https://semanticscholar.org/paper/a80f8097a4cfe0aeabe52a50e789f4b2867391a3 }}</ref> and feature representation.<ref name="Luck_1998"/>

=== Low resolution representations and limited capacity ===

Additional theories in vision science propose that stimuli are represented in the brain individually as small, low resolution, icons stored in templates with limited capacities and are organized through associative links.<ref>{{cite book | vauthors = Nakayama K | chapter = The iconic bottleneck and the tenuous link between early visual processing and perception. | veditors = Adler K, Pointon M | title = Vision: Coding and efficiency |chapter-url=https://books.google.com/?id=xGJ_DxN3eygC&pg=PA411 |date=1993-05-13 |publisher= Cambridge University Press|isbn=978-0-521-44769-0 }}</ref><ref>{{cite book | vauthors = Neisser U | date = 1967 | title = Cognitive Psychology | ___location = New York | publisher = Appleton-Cent }}</ref>

== History ==

Throughout its history, ensemble coding been known by many names. Interest in the theory began to emerge in the early 20th century.<ref name="Wolfe_2011" /> In its earliest years, ensemble coding was known as [[Gestalt grouping rules|Gestalt grouping]].<ref name="Wolfe_2011" /> In 1923, Max Wertheimer, a [[Gestalt psychology]] theorist, was addressing how humans perceive their visual world holistically rather than individually.<ref>{{cite journal | vauthors = Wertheimer M | title = Untersuchungen zur Lehre von der Gestalt. II. | trans-title = Investigations into the teaching of the form | language = German | journal = Psychological Research | date = January 1923 | volume = 4 | issue = 1 | pages = 301–50 | doi = 10.1007/BF00410640 }}</ref> Gestaltists argued that in object perception, the individual object features were either lost or difficult to perceive and therefore the grouped object was the favored percept.<ref>Koffka, K. (1935). The Principles of Gestalt Psychology. London: Routledge and Kegan Paul Ltd.</ref> Although Gestaltists helped define some of the central principles of object perception, research into modern ensemble coding did not occur until many years later.{{cn|date=December 2019}}

In 1971, [[Norman H. Anderson|Norman Anderson]] was one of the earliest to conduct explicit ensemble coding research.<ref name="Haberman_2012" /><ref name=":1">{{Cite journal|last=Anderson|first=Norman H.|date=1971|title=Integration theory and attitude change.|url=http://content.apa.org/journals/rev/78/3/171|journal=Psychological Review|language=en|volume=78|issue=3|pages=171–206|doi=10.1037/h0030834|issn=0033-295X}}</ref> Anderson's research into social ensemble coding showed that individuals described by two positive terms were rated more favorably than individuals described by two positive terms and two negative terms.<ref name=":0">{{Cite journal|last=Anderson|first=Norman H.|date=1965|title=Averaging versus adding as a stimulus-combination rule in impression formation.|url=http://doi.apa.org/getdoi.cfm?doi=10.1037/h0022280|journal=Journal of Experimental Psychology|language=en|volume=70|issue=4|pages=394–400|doi=10.1037/h0022280|pmid=5826027|issn=0022-1015}}</ref> This research on [[impression formation]] demonstrated that a weighted mean or average captures how information is integrated rather than the summation.<ref name=":0" /> Additional research during this time explored ensemble coding in group attractiveness,<ref>Anderson, N. H., Lindner, R., & Lopes, L. L. (1973). Integration Theory Applied to Judgments of Group Attractiveness. Journal of Personality and Social Psychology, 26(3), 400-408.</ref> shopping preferences,<ref>Levin, I. P. (1974). Averaging Processes in Ratings and Choices Based on Numerical Information. Memory & Cognition, 2(4), 786-790.</ref> and the perceived badness of criminals.<ref>Leon, M., Oden, G. C., & Anderson, N. H. (1973). Functional Measurement of Social Values. Journal of Personality and Social Psychology, 27(3), 301-310.</ref>

== The current era ==

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Consistent with Ariely's findings,<ref name="Ariely_2001" /> follow-up research conducted by Sang Chul Chong and Anne Treisman in 2003 provided evidence that participants are engaging in summary statistical processes. Their research revealed that participant's maintained high accuracy in encoding the mean size of the stimuli even with short stimuli presentations as low as 50 milliseconds, memory delays, and object distribution differences.<ref name="Chong_2003">{{cite journal | vauthors = Chong SC, Treisman A | title = Representation of statistical properties | journal = Vision Research | volume = 43 | issue = 4 | pages = 393–404 | date = February 2003 | pmid = 12535996 | doi = 10.1016/S0042-6989(02)00596-5 }}</ref>

Additional research has demonstrated that ensemble coding is not limited to the mean size of objects in the ensemble,<ref name="Ariely_2001" /> but that additional content is extracted, such as average line orientation,<ref name="Dakin_1997">{{cite journal | vauthors = Dakin SC, Watt RJ | title = The computation of orientation statistics from visual texture | journal = Vision Research | volume = 37 | issue = 22 | pages = 3181–92 | date = November 1997 | pmid = 9463699 | doi = 10.1016/S0042-6989(97)00133-8 }}</ref> average spatial ___location,<ref name="Alvarez_2008">{{cite journal | vauthors = Alvarez GA, Oliva A | title = The representation of simple ensemble visual features outside the focus of attention | journal = Psychological Science | volume = 19 | issue = 4 | pages = 392–8 | date = April 2008 | pmid = 18399893 | pmc = 2587223 | doi = 10.1111/j.1467-9280.2008.02098.x }}</ref> average number,<ref name="Halberda_2006">{{cite journal | vauthors = Halberda J, Sires SF, Feigenson L | title = Multiple spatially overlapping sets can be enumerated in parallel | journal = Psychological Science | volume = 17 | issue = 7 | pages = 572–6 | date = July 2006 | pmid = 16866741 | doi = 10.1111/j.1467-9280.2006.01746.x }}</ref> and statistical summaries such as the variances<ref>{{cite journal | vauthors = Solomon JA, Morgan M, Chubb C | title = Efficiencies for the statistics of size discrimination | journal = Journal of Vision | volume = 11 | issue = 12 | pages = 13 | date = October 2011 | pmid = 22011381 | pmc = 4135075 | doi = 10.1167/11.12.13 }}</ref> are detected. Observers are also able to extract accurate perceptual summaries of high-level features such as the average direction of eye gaze of grouped faces<ref>{{Cite journal|last=Sweeny|first=Timothy D.|last2=Whitney|first2=David|date=October 2014|title=Perceiving Crowd Attention: Ensemble Perception of a Crowd’sCrowd's Gaze|url=http://journals.sagepub.com/doi/10.1177/0956797614544510|journal=Psychological Science|language=en|volume=25|issue=10|pages=1903–1913|doi=10.1177/0956797614544510|issn=0956-7976|pmc=4192023|pmid=25125428}}</ref> and the average walking direction of a crowd.<ref>{{Cite journal|last=Sweeny|first=Timothy D.|last2=Haroz|first2=Steve|last3=Whitney|first3=David|date=2013|title=Perceiving group behavior: Sensitive ensemble coding mechanisms for biological motion of human crowds.|url=http://doi.apa.org/getdoi.cfm?doi=10.1037/a0028712|journal=Journal of Experimental Psychology: Human Perception and Performance|language=en|volume=39|issue=2|pages=329–337|doi=10.1037/a0028712|pmid=22708744|issn=1939-1277}}</ref>

== Levels of ensemble coding ==

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Based on the early work of Anderson,<ref name=":1" /> it appears that humans integrate semantic as well as social information using ensemble coding. These findings suggest that social processes may hinge on the same sort of underlying mechanisms that allow people to perceive average object orientation <ref name="Dakin_1997" /> and average object direction of motion.<ref name=":2" /><ref name=":3" /><ref name="Haberman_2012" />

In recent years, ensemble coding in the field of [[social vision]] has emerged. Social vision is a field of research that examines how people perceive one another. With the addition of ensemble coding, the field is able to explore people perception, or how people perceive groups of other people. This specific research area focuses on how observers accurately perceive and extract social information from groups and how that extracted information influences downstream judgments and behaviors.<ref name=":4">{{Cite journal|last=Goodale|first=Brianna M.|last2=Alt|first2=Nicholas P.|last3=Lick|first3=David J.|last4=Johnson|first4=Kerri L.|date=November 2018|title=Groups at a glance: Perceivers infer social belonging in a group based on perceptual summaries of sex ratio.|url=http://doi.apa.org/getdoi.cfm?doi=10.1037/xge0000450|journal=Journal of Experimental Psychology: General|language=en|volume=147|issue=11|pages=1660–1676|doi=10.1037/xge0000450|pmid=30372114|issn=1939-2222}}</ref> In 2018, seminal research introducing the use ensemble coding in the field of social vision was conducted by Briana Goodale. Goodale's research found that humans can accurately extract sex ratio summaries from ensembles of faces and that this sex ratio provides an early visual cue signaling sense of belonging and fit within group.<ref name=":4" /> Specifically, this research found that participants felt a stronger sense of belonging to a given ensemble as members of their own sex increased in the perceived ensemble.<ref name=":4" />

Additional research has uncovered that in as little as 75 milliseconds, participants are able to derive the average sex ratio of an ensemble of faces.<ref name=":5" /> Furthermore, within that 75 milliseconds, participants were able to form impressions based on the perceived sex ratio and make inferences about the groups perceived threat.<ref name=":5" /> Specifically, this research found that groups were judged as more threatening as the ratio of men to women increased.<ref name=":5" />