Editing Grid illusion (section)

==Theories==
The effect of both optical illusions is often explained by a neural process called [[lateral inhibition]].<ref name=Baumgartner>{{cite journal |doi=10.1007/BF00680926 |author=Baumgartner G |year=1960 |title=Indirekte Größenbestimmung der rezeptiven Felder der Retina beim Menschen mittels der Hermannschen Gittertäuschung. |journal=Pflügers Archiv für die gesamte Physiologie |volume=272 |pages=21–22|s2cid=45209673 }}</ref> The intensity at a point in the visual system is not simply the result of a single [[sensory receptor|receptor]], but the result of a group of receptors which respond to the presentation of stimuli in what is called a [[receptive field]].

A [[retinal ganglion cell]] pools the inputs of several [[Photoreceptor cell|photoreceptors]] over an area of the [[retina]]; the area in physical space to which the photoreceptors respond is the ganglion cell's "receptive field". In the center of a so-called on-center receptive field, the individual photoreceptors ''excite'' the ganglion cell when they detect increased luminance; the photoreceptors in the surrounding area ''inhibit'' the ganglion cell. Thus, since a point at an intersection is surrounded by more areas of intensity than a point at the middle of a line, the intersection appears darker due to the increased inhibition.

There is strong evidence that the retinal ganglion cell theory is untenable. For example, making the lines of the grid wavy rather than straight eliminates both the Hermann grid and scintillating grid illusions.<ref name=Lingelbach_1985>{{cite journal | vauthors= Lingelbach B, Block B, Hatzky B, Reisinger E |year=1985 |title= The Hermann grid illusion–retinal or cortical?|journal=Perception |volume=14 |issue=1 |pages=A7 }}</ref><ref name=Geier_2004>{{cite book|vauthors=Geier J, Bernáth L |year=2004 |chapter= Stopping the Hermann grid illusion by simple sine distortion |title=Perception |pages=33–53 | isbn=0631224211 |publisher=Malden Ma: Blackwell}}</ref><ref name="Schiller">{{cite journal | last1=Schiller | first1=Peter H. | last2=Carvey | first2=Christina E. | title=The Hermann grid illusion revisited | journal=Perception | year=2005 | volume=34 | issue=11 | pages=1375–1397 | url=http://www.perceptionweb.com/abstract.cgi?id=p5447 | doi=10.1068/p5447 | pmid=16355743 | s2cid=15740144 | access-date=2011-10-03 | archive-url=https://web.archive.org/web/20111212013609/http://perceptionweb.com/abstract.cgi?id=p5447 | archive-date=2011-12-12 | url-status=dead | url-access=subscription }}</ref><ref name="Geier_2008">{{cite journal |doi=10.1068/p5622 |vauthors=Geier J, Bernáth L, Hudák M, Séra L |year=2008 |title=Straightness as the main factor of the Hermann grid illusion |journal=Perception |volume=37 |issue=5 |pages=651–665 |pmid=18605141|s2cid=21028439 }}</ref><ref>{{cite web |url=http://www.geier.hu/Hermann/index.html |title=Stopping the Hermann grid illusion by sine distortion |first=János |last=Geier |year=2008}}</ref><ref name=Bach_2008>{{cite journal |author=Bach, Michael |year=2008 |title= Die Hermann-Gitter-Täuschung: Lehrbucherklärung widerlegt (The Hermann grid illusion: the classic textbook interpretation is obsolete) | journal=Ophthalmologe | doi=10.1007/s00347-008-1845-5 |pmid=18830602 |volume=106 |issue=10 |pages=913–917}}</ref>
The Baumgartner / RGC theory does not predict this outcome. Lateral inhibition theory also can not account for the fact that the Hermann grid illusion is perceived over a range of bar widths.<ref name="Schiller" /> Lateral inhibition theory would predict that decreasing the size of the grid (and therefore decreasing the amount of inhibition at the intersection) would eradicate the illusory effect. One alternative explanation is that the illusion is due to S1 type [[simple cell]]s in the visual cortex.<ref name="Schiller" />

It has been hypothesized that the effect is caused by movement of the [[physiological blind spot]].<ref>{{cite journal |last1=Nishiyama |first1=Yutaka |title=Dynamic transitions of blind spots in the Hermann grid illusion |journal=Journal of Osaka University of Economics |date=2024 |volume=75 |issue=4 |pages=169–177 |doi=10.24644/keidaironshu.75.4_169 |url=https://www.jstage.jst.go.jp/article/keidaironshu/75/4/75_169/_article/-char/en |access-date=12 February 2025 |issn=0474-7909 |eissn=2433-5681 |lang=en |doi-access=free}}</ref>