Editing Eye tracking (section)

== History ==
[[File:Yarbus eye tracker.jpg|thumb|Yarbus eye tracker from the 1960s]]

In the 1800s, studies of eye movement were made using direct observations. For example, [[Louis Émile Javal]] observed in 1879 that reading does not involve a smooth sweeping of the eyes along the text, as previously assumed, but a series of short stops (called [[Fixation (visual)|fixations]]) and quick [[saccade]]s.<ref>Reported in {{harvnb|Huey|1908/1968}}</ref>  This observation raised important questions about reading, questions which were explored during the 1900s: On which words do the eyes stop? For how long? When do they regress to already seen words?

[[File:Reading Fixations Saccades.jpg|thumb|left|upright=1.5|An example of [[Fixation (visual)|fixations]] and [[saccade]]s over text. This is the typical pattern of eye movement during reading. The eyes never move smoothly over still text.]]

Edmund Huey<ref>{{cite book|last=Huey|first=Edmund |date=1968 |orig-date=originally published 1908 |title=The Psychology and Pedagogy of Reading |publisher=MIT Press |edition=Reprint |ref={{harvid|Huey|1908/1968}} }}</ref> built an early eye tracker, using a sort of contact lens with a hole for the [[pupil]]. The lens was connected to an aluminum pointer that moved in response to the movement of the eye. Huey studied and quantified regressions (only a small proportion of saccades are regressions), and he showed that some words in a sentence are not fixated.

The first non-intrusive eye-trackers were built by Guy Thomas Buswell in Chicago, using beams of light that were reflected on the eye, then recording on film. Buswell made systematic studies into reading<ref>{{cite periodical |last=Buswell |first=G.T. |year=1922 |title=Fundamental reading habits: a study of their development |publisher=University of Chicago |magazine=Supplementary Educational Monographs |place=Chicago |issue=21}}</ref><ref>{{cite periodical |last=Buswell |first=G.T. |year=1937 |title=How adults read |publisher=University of Chicago |magazine=Supplementary Educational Monographs |place=Chicago |issue=45}}</ref> and picture viewing.<ref>{{citation |last=Buswell |first=G.T. |year=1935 |title=How people look at pictures: a study of the psychology and perception in art |publisher=University of Chicago Press |id=[[Trove]] [https://trove.nla.gov.au/work/12223957 12223957]}}</ref>

In the 1950s, [[Alfred L. Yarbus]]<ref>{{cite book |last1=Yarbus |first1=Alfred L. |title=Eye movements and vision |date=1967 |publisher=Plenum Press |location=New York |isbn=978-1-4899-5379-7 |url=http://wexler.free.fr/library/files/yarbus%20%281967%29%20eye%20movements%20and%20vision.pdf |access-date=24 March 2022}}</ref> performed eye tracking research, and his 1967 book is often quoted. He showed that the task given to a subject has a very large influence on the subject's eye movement. He also wrote about the relation between fixations and interest:

{{quote|All the records ... show conclusively that the character of the eye movement is either completely independent of or only very slightly dependent on the material of the picture and how it was made, provided that it is flat or nearly flat."<ref name="Yarbus 1967 190">{{Harvnb|Yarbus|1967|p=190}}</ref>}}
The cyclical pattern in the examination of pictures "is dependent on not only what is shown on the picture, but also the problem facing the observer and the information that he hopes to gain from the picture."<ref>{{Harvnb|Yarbus|1967|p=194}}</ref>

[[Image:Yarbus The Visitor.jpg|thumb|right|upright=1.5|This study by {{Harvtxt|Yarbus|1967}} is often referred to as evidence on how the task given to a person influences his or her eye movement.]]

{{quote|Records of eye movements show that the observer's attention is usually held only by certain elements of the picture.... Eye movement reflects the human thought processes; so the observer's thought may be followed to some extent from records of eye movement (the thought accompanying the examination of the particular object). It is easy to determine from these records which elements attract the observer's eye (and, consequently, his thought), in what order, and how often.<ref name="Yarbus 1967 190"/>}}

{{quote|The observer's attention is frequently drawn to elements which do not give important information but which, in his opinion, may do so. Often an observer will focus his attention on elements that are unusual in the particular circumstances, unfamiliar, incomprehensible, and so on.<ref>{{Harvnb|Yarbus|1967|p=191}}</ref>}}

{{quote|... when changing its points of fixation, the observer's eye repeatedly returns to the same elements of the picture. Additional time spent on perception is not used to examine the secondary elements, but to reexamine the most important elements.<ref>{{Harvnb|Yarbus|1967|p=193}}</ref>}}

[[Image:Eye tracking thru glass.JPG|thumb|This study by Hunziker (1970)<ref name="forsch1e.htm">{{Cite web|url=http://www.learning-systems.ch/multimedia/forsch1e.htm|title=Visual Perception: Eye Movements in Problem Solving.|website=www.learning-systems.ch}}</ref> on ''eye tracking in problem solving'' used simple 8&nbsp;mm film to track eye movement by filming the subject through a glass plate on which the visual problem was displayed.<ref>[http://www.learning-systems.ch/multimedia/eye%20movements%20problem%20solving.swf] {{webarchive|url=https://web.archive.org/web/20110706235011/http://www.learning-systems.ch/multimedia/eye%20movements%20problem%20solving.swf|date=2011-07-06}}</ref><ref name="forsch1e.htm"/>]]

In the 1970s, eye-tracking research expanded rapidly, particularly reading research. A good overview of the research in this period is given by [[Dr. Keith Rayner|Rayner]].<ref>{{harvnb|Rayner|1978}}</ref>

In 1980, Just and Carpenter<ref>{{harvnb|Just|Carpenter|1980}}</ref> formulated the influential ''Strong eye-mind hypothesis'', that "there is no appreciable lag between what is fixated and what is processed". If this hypothesis is correct, then when a subject looks at a word or object, he or she also thinks about it (process cognitively), and for exactly as long as the recorded fixation. The hypothesis is often taken for granted by researchers using eye-tracking. However, [[Gaze-contingency paradigm|gaze-contingent techniques]] offer an interesting option in order to disentangle overt and covert attentions, to differentiate what is fixated and what is processed.

During the 1980s, the eye-mind hypothesis was often questioned in light of covert attention,<ref>{{cite journal | last=Posner | first=Michael I. | title=Orienting of Attention | journal=Quarterly Journal of Experimental Psychology | publisher=SAGE Publications | volume=32 | issue=1 | year=1980 | issn=0033-555X | doi=10.1080/00335558008248231 | pages=3–25| pmid=7367577 | s2cid=2842391 }}</ref><ref>{{cite book | last1=Wright | first1=R.D. | last2=Ward | first2=L.M. | title=Orienting of Attention | publisher=Oxford University Press | year=2008 | isbn=978-0-19-802997-7 | url=https://books.google.com/books?id=b_HSJKidixAC }}</ref> the attention to something that one is not looking at, which people often do. If covert attention is common during eye-tracking recordings, the resulting scan-path and fixation patterns would often show not where attention has been, but only where the eye has been looking, failing to indicate cognitive processing.

The 1980s also saw the birth of using eye-tracking to answer questions related to human-computer interaction. Specifically, researchers investigated how users search for commands in computer menus.<ref name="10.1.1.100.445">{{cite book |chapter=Eye Tracking in Human–Computer Interaction and Usability Research: Ready to Deliver the Promises |author1=Robert J. K. Jacob |author2=Keith S. Karn |title=The Mind's Eye: Cognitive and Applied Aspects of Eye Movement Research |editor1=Hyona |editor2=Radach |editor3=Deubel |location=Oxford, England |year=2003 |publisher=Elsevier Science BV |isbn=0-444-51020-6 |citeseerx=10.1.1.100.445 |chapter-url-access=registration |chapter-url=https://archive.org/details/mindseyecognitiv0000unse }}</ref>  Additionally, computers allowed researchers to use eye-tracking results in real time, primarily to help disabled users.<ref name="10.1.1.100.445"/>

More recently, there has been growth in using eye tracking to study how users interact with different computer interfaces. Specific questions researchers ask are related to how easy different interfaces are for users.<ref name="10.1.1.100.445"/>  The results of the eye tracking research can lead to changes in design of the interface. Another recent area of research focuses on Web development. This can include how users react to drop-down menus or where they focus their attention on a website so the developer knows where to place an advertisement.<ref>{{cite web |url=http://www.mmi-interaktiv.de/uploads/media/MMI-Interaktiv0303_SchiesslDudaThoelkeFischer.pdf |title=Eye tracking and its application in usability and media research |last1=Schiessl |first1=Michael |last2=Duda |first2=Sabrina |last3=Thölke |first3=Andreas |last4=Fischer |first4=Rico}}</ref>

According to Hoffman,<ref>{{cite book | last=Hoffman | first=James E. | chapter=Visual attention and eye movements | editor-last=Pashler | editor-first=H. | title=Attention | publisher=Taylor & Francis | series=Studies in Cognition | year=2016 | isbn=978-1-317-71549-8 | chapter-url=https://books.google.com/books?id=Yep5CwAAQBAJ&pg=PA119 | pages=119–153 }}</ref> current consensus is that visual attention is always slightly (100 to 250 ms) ahead of the eye. But as soon as attention moves to a new position, the eyes will want to follow.<ref>{{cite journal | doi=10.1016/0042-6989(95)00294-4 | volume=36 | issue=12 | title=Saccade target selection and object recognition: Evidence for a common attentional mechanism | year=1996 | journal=Vision Research | pages=1827–1837 | last1=Deubel | first1=Heiner | pmid=8759451 | s2cid=16916037 | doi-access=free }}</ref>

Specific cognitive processes still cannot be inferred directly from a fixation on a particular object in a scene.<ref>{{cite book |last=Holsanova |first=Jana |chapter=Användares interaktion med multimodala texter |trans-chapter=User interaction with multimodal texts |chapter-url=https://www.researchgate.net/publication/237665654 |editor1=L. Gunnarsson |editor2=A.-M. Karlsson |title=Ett vidgat textbegrepp |trans-title= |year=2007 |pages=41–58 |language=sv}}</ref> For instance, a fixation on a face in a picture may indicate recognition, liking, dislike, puzzlement etc. Therefore, eye tracking is often coupled with other methodologies, such as [[Protocol analysis|introspective verbal protocols]].

Thanks to advancement in portable electronic devices, portable head-mounted eye trackers currently can achieve excellent performance and are being increasingly used in research and market applications targeting daily life settings.<ref>{{cite journal | doi=10.1177/2055668318773991 | pmid=31191938 | pmc=6453044 | title=Head-mounted eye gaze tracking devices: An overview of modern devices and recent advances. | year=2018 | journal=Journal of Rehabilitation and Assistive Technologies Engineering | volume=5 | pages=205566831877399 |vauthors=Cognolato M, Atzori M, Müller H}}</ref> These same advances have led to increases in the study of small eye movements that occur during fixation, both in the lab and in applied settings.<ref name="bop.unibe.ch">{{cite journal |last1=Alexander |first1=Robert |last2=Macknik |first2=Stephen |last3=Martinez-Conde |first3=Susana |title=Microsaccades in applied environments: Real-world applications of fixational eye movement measurements |journal=Journal of Eye Movement Research |date=2020 |volume=12 |issue=6 |pmid=33828760|doi=10.16910/jemr.12.6.15 |pmc=7962687 |doi-access=free }}</ref>
[[File:Typical cnn.png|thumb|The use of convolutional neural networks in eye-tracking allow for new information to be identified by artificial intelligence.]]
In the 21st century, the use of [[artificial intelligence]] (AI) and [[artificial neural network]]s has become a viable way to complete eye-tracking tasks and analysis. In particular, the [[convolutional neural network]] lends itself to eye-tracking, as it is designed for image-centric tasks. With AI, eye-tracking tasks and studies can yield additional information that may not have been detected by human observers. The practice of [[deep learning]] also allows for a given neural network to improve at a given task when given enough sample data. This requires a relatively large supply of training data, however.<ref name=":0" />

The potential use cases for AI in eye-tracking cover a wide range of topics from medical applications<ref>{{Cite journal|last1=Stember|first1=J. N.|last2=Celik|first2=H.|last3=Krupinski|first3=E.|last4=Chang|first4=P. D.|last5=Mutasa|first5=S.|last6=Wood|first6=B. J.|last7=Lignelli|first7=A.|last8=Moonis|first8=G.|last9=Schwartz|first9=L. H.|last10=Jambawalikar|first10=S.|last11=Bagci|first11=U.|date=August 2019|title=Eye Tracking for Deep Learning Segmentation Using Convolutional Neural Networks|journal=Journal of Digital Imaging|language=en|volume=32|issue=4|pages=597–604|doi=10.1007/s10278-019-00220-4|issn=0897-1889|pmc=6646645|pmid=31044392}}</ref> to driver safety<ref name=":0" /> to game theory<ref name=":1" /> and even education and  training applications.<ref>{{cite journal |last1=Nadu |first1=T |title=A review: Towards quality improvement in real time eye-tracking and gaze detection |journal=International Journal of Applied Engineering Research |date=2015 |volume=10 |issue=6}}</ref><ref>{{cite journal |last1=Nückles |first1=M |title=Investigating visual perception in teaching and learning with advanced eye-tracking methodologies: Rewards and challenges of an innovative research paradigm |journal=Educational Psychology Review |date=2021 |volume=33 |issue=1|pages=149–167 |doi=10.1007/s10648-020-09567-5 |s2cid=225345884 |doi-access=free }}</ref><ref>{{cite journal |last1=Alexander |first1=RG |last2=Waite |first2=S |last3=Macknik |first3=SL |last4=Martinez-Conde |first4=S |title=What do radiologists look for? Advances and limitations of perceptual learning in radiologic search. |journal=Journal of Vision |date=2020 |volume=20 |issue=10 |page=17 |doi=10.1167/jov.20.10.17|pmid=33057623 |pmc=7571277 }}</ref>