146:
in
Breslau/Poland described the percept of two neighboring points in indirect vision as “quite strangely undefined as something black, the form of which cannot be further specified”. Note that, in none of these examples, the description is as "blurred" or "distorted", as is often (and misleadingly)
80:
and may have clinical implications in these disorders. It is also suggested that head injuries can cause a crowding effect. Normally sighted children up to the age of about eight years further have more pronounced crowding than adults, and this may be the reason for larger print in children's books.
126:
Crowding, as we know today, is – except in a few special circumstances – the essential bottleneck for human pattern recognition and can be demonstrated in the easiest of ways. It is thus striking that it has been overlooked over the centuries; the cause for degraded pattern recognition has mostly
105:
Newer research suggests that the factor in Bouma's rule (originally ½) can vary quite a bit, and might often be a little smaller (e.g., 0.4). Furthermore, a small constant should be added in the equation, and there are further caveats. Overall, however, Bouma's rule has since proven valid over a
150:
Crowding itself, however, i.e. the difference between singular letters and groups thereof, went unnoticed up to the 20th century. In 1924, then, the
Gestalt psychologist Wilhelm Korte was the first to describe, in detail, percepts and phenomena of form perception in indirect vision
181:
found increasingly wide attention in visual perception research (Levi et al. 1985; Strasburger et al., 1991; Toet & Levi, 1992, Pelli et al., 2004). Today, it is a major topic in vision and perception and is increasingly recognized for being the major limitation of foveal and
61:. Yet, while it is indeed particularly prominent there, it is present in the whole of the visual field, with only its spatial extent varying (governed by Bouma's law; see below). In particular, crowding is of utmost importance in foveal vision, overriding the importance of
101:
away from the fovea's center). If, e.g., a letter is shown at 2.5 deg away from the fovea center – which is approximately at the border of the fovea – the critical distance amounts to 1.25 deg visual angle. When the flankers are closer, crowding will thus occur.
177:, in 1970, famously found what was later called Bouma's law, yet that paper was fully neglected for many years. In the coming three decades, the phenomenon was studied in experimental psychology, under different terms. Only then, the subject of
963:
For illustration: The thumb, held at arm's length, subtends about 2.5 deg visual angle. Two adjacent thumbs at arm's length thus correspond roughly to the size of the fovea. In a group of people, that might be the size of another person's
661:
refers to the situation where the observer fixates a visual object and, depending on the latter, uses anything between the tiny region of highest acuity (in acuity measurements) or the whole of the fovea and more (in
27:
A demonstration of the crowding effect. Fixate on the "x" and attempt to identify the central (or single) letter appearing to the right. The presence of flankers should make the task more difficult.
163:, as is apparent from a remark of the Danish ophthalmologist Holger Ehlers in 1936. James A. Stuart und Hermann M. Burian in Iowa were, in 1962, the first to study crowding systematically, for
46:
is impaired by the presence of other neighbouring objects (sometimes called "flankers"). It has been suggested that crowding occurs due to mandatory integration of the crowded objects by a
97:
has described a rule-of-thumb for that critical distance, stating that it amounts to about half the eccentricity value under which the crowded letter is seen (eccentricity measured as
39:
138:
in 1738 described the phenomenon of "indistinct vision" which, in two examples, could be seen as the result of crowding. In the 19th century, the ophthalmologists
1282:
72:
and has been first mentioned in that context and studied quantitatively there. Crowding deficits have further been found in neuropsychiatric disorders such as
93:. Instead, it depends very systematically on the distance to its neighbors. If the latter is above a critical value, crowding vanishes. In 1970,
894:
106:
large variety of perceptual tasks. For its robustness, it is now often considered a perceptual law, similar to other perceptual laws (like
1108:
Aubert, H.R.; Förster, C. F. R. (1857). "Beiträge zur
Kenntniss des indirecten Sehens. (I). Untersuchungen ĂĽber den Raumsinn der Retina".
758:
Stuart, J.A.; Burian, H.M. (1962). "A study of separation difficulty: its relationship to visual acuity in normal and amblyopic eyes".
574:
Stevens' Handbook of
Experimental Psychology and Cognitive Neuroscience, Sensation, Perception, and Attention, Fourth Edition Volume 2
24:
861:
581:
251:
Parkes L; Lund J; Angelucci A; Solomon JA; Morgan M (2001). "Compulsory averaging of crowded orientation signals in human vision".
143:
447:
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subjects. In foveal vision, the related phenomenon of contour interaction was described (Merton Flom, Frank
Weymouth &
1287:
54:
since it is "a form of integration over space as target features are spuriously combined with flanker features."
877:
Atkinson, J.; Pimm-Smith, E.; Evans, C.; Harding, G.; Braddick, O. (1986). "Visual
Crowding in Young Children".
1297:
139:
51:
107:
1292:
155:). Probably around that time, crowding has become an issue in optometry and ophthalmology when testing
50:, but there are several competing theories about the underlying mechanisms. It is considered a kind of
89:
The extent of crowding is mostly independent of a letter's or form's size, unlike what is the case in
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Attention
Deficit Hyperactivity Disorder Handbook: A Physician's Guide to ADHD, Second Edition
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in pattern recognition and reading where crowding represents the bottleneck in processing.
168:
43:
461:
442:
1205:
976:"Crowding is unlike ordinary masking: Distinguishing feature integration from detection"
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1230:"Visual crowding: A fundamental limit on conscious perception and object recognition"
771:
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62:
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Pelli, D.G.; Tillman, K.A.; Freeman, J.; Su, M.; Berger, T.D.; Majaj, N.J. (2007).
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98:
94:
17:
394:"Dancing letters and ticks that buzz around aimlessly – On the origin of crowding"
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886:
819:
357:
219:
1068:
881:. Documenta Ophthalmologica Proceedings Series. Vol. 45. pp. 201–213.
135:
1245:
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Bouma, Herman (1970). "Interaction effects in parafoveal letter recognition".
35:
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204:"Crowding - an essential bottleneck for object recognition: a mini-review"
23:
342:"Crowding – an essential bottleneck for object recognition: a minireview"
115:
492:
Strasburger, H. (2020). "On the cortical mapping function (Preprint)".
57:
Crowding has long been thought to be predominantly a characteristic of
934:
879:
Detection and
Measurement of Visual Impairment in Pre-Verbal Children
795:"Crowding deficits in the visual periphery of schizophrenia patients"
77:
1195:
1032:
992:
793:
Kraehenmann, Rainer; Vollenweider FX; Seifritz E; Kometer M (2012).
525:"Crowding, grouping, and object recognition: A matter of appearance"
127:
been, and still is, incorrectly ascribed to degraded visual acuity.
1085:
720:
Ehlers, Holger (1936). "The movements of the eyes during reading".
694:
540:
501:
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22:
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The percepts in peripheral vision have already been described by
523:
Herzog, M. H.; Sayim, B.; Chicherov, V.; Manassi, M. (2015).
1069:"James Jurin (1684–1750): A pioneer of crowding research?"
856:. New York: Springer Science+Business Media. p. 17.
134:
in the 11th century as "confused and obscure". Later,
1179:"Peripheral vision and pattern recognition: a review"
1177:
Strasburger, H.; Rentschler, I.; JĂĽttner, M. (2011).
974:
Pelli, Denis G.; Palomares, M.; Majaj, N.J. (2004).
576:. Hoboken, NJ: John Wiley & Sons. p. 833.
443:"Capabilities and limitations of peripheral vision"
678:"Crowding and eccentricity determine reading rate"
387:
385:
753:
751:
1130:"Seven myths on crowding and peripheral vision"
612:"Seven myths on crowding and peripheral vision"
1062:
1060:
715:
713:
908:
906:
8:
1017:"The uncrowded window of object recognition"
1015:Pelli, D.G.; Tillman, Katharine A. (2008).
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16:For the medical sociology concept, see
1283:Object recognition and categorization
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1067:Strasburger, H.; Wade, N.J. (2015).
462:10.1146/annurev-vision-082114-035733
296:"Crowding: A neuroanalytic approach"
147:seen in today's characterizations.
68:Crowding is prominently present in
48:texture-processing neural mechanism
734:10.1111/j.1755-3768.1936.tb07306.x
666:) for processing the visual input.
294:Tyler, C.W.; Likova, L.T. (2007).
14:
760:American Journal of Ophthalmology
1228:Whitney, D.; Levi, D.M. (2011).
448:Annual Review of Vision Science
1:
1234:Trends in Cognitive Sciences
887:10.1007/978-94-009-4263-9_27
820:10.1371/journal.pone.0045884
772:10.1016/0002-9394(62)94878-X
358:10.1016/j.visres.2007.12.009
220:10.1016/j.visres.2007.12.009
1314:
1246:10.1016/j.tics.2011.02.005
1128:Strasburger, Hans (2020).
986:(12): 1129–111136–116935.
852:Millichap, Gordon (2009).
610:Strasburger, Hans (2020).
184:peripheral form perception
34:(or visual crowding) is a
15:
1110:Archiv fĂĽr Ophthalmologie
1146:10.1177/2041669520913052
628:10.1177/2041669520913052
392:Strasburger, H. (2014).
340:Levi, Dennis M. (2008).
202:Levi D (February 2008).
42:presented away from the
441:Rosenholtz, R. (2016).
40:recognition of objects
28:
572:Wixted, John (2018).
38:phenomenon where the
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722:Acta Ophthalmologica
1021:Nature Neuroscience
927:1970Natur.226..177B
811:2012PLoSO...745884K
253:Nature Neuroscience
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29:
1288:Visual perception
1183:Journal of Vision
1073:Journal of Vision
1027:(10): 1129–1135.
980:Journal of Vision
921:(5241): 177–178.
896:978-94-010-8393-5
682:Journal of Vision
529:Journal of Vision
300:Journal of Vision
153:peripheral vision
59:peripheral vision
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1240:(4): 160–168.
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352:(5): 635–654.
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313:10.1167/7.2.16
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259:(7): 739–744.
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214:(5): 635–654.
193:
191:
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159:subjects with
140:Hermann Aubert
132:Ibn al-Haytham
123:
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95:Herman Bouma
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30:
18:Overcrowding
1189:(5): 1–82.
1140:(2): 1–45.
766:: 471–477.
622:(2): 1–45.
455:: 437–457.
136:James Jurin
116:Bloch's law
112:Riccò's law
108:Weber's law
85:Bouma's law
1277:Categories
398:Perception
190:References
161:eye charts
36:perceptual
728:: 56–63.
510:149700090
479:207728323
171:, 1963).
165:amblyopic
157:amblyopic
70:amblyopia
1264:21420894
1215:22207654
1206:11073400
1164:32489576
1095:25589293
1051:18828191
1002:15669917
951:29459715
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799:PLOS ONE
780:13917936
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428:26136221
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281:10975462
273:11426231
238:18226828
179:Crowding
52:grouping
32:Crowding
1255:3070834
1155:7238452
1116:: 1–37.
1042:2772078
943:5437004
923:Bibcode
830:3458825
807:Bibcode
664:reading
637:7238452
550:4429926
494:bioRxiv
367:2268888
229:2268888
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78:autism
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738:S2CID
506:S2CID
475:S2CID
424:S2CID
277:S2CID
44:fovea
1260:PMID
1211:PMID
1160:PMID
1091:PMID
1047:PMID
998:PMID
964:head
939:PMID
891:ISBN
858:ISBN
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700:PMID
642:PMID
578:ISBN
555:PMID
467:PMID
416:PMID
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318:PMID
269:PMID
234:PMID
142:and
76:and
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1242:doi
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632:PMC
624:doi
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362:PMC
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224:PMC
216:doi
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