Crowding is unlike ordinary masking: distinguishing feature integration from detection. Pelli, D. G., Palomares, M., & Majaj, N. J. J Vis, 4(12):1136–1169, 2004. doi abstract bibtex A letter in the peripheral visual field is much harder to identify in the presence of nearby letters. This is "crowding." Both crowding and ordinary masking are special cases of "masking," which, in general, refers to any effect of a "mask" pattern on the discriminability of a signal. Here we characterize crowding, and propose a diagnostic test to distinguish it from ordinary masking. In ordinary masking, the signal disappears. In crowding, it remains visible, but is ambiguous, jumbled with its neighbors. Masks are usually effective only if they overlap the signal, but the crowding effect extends over a large region. The width of that region is proportional to signal eccentricity from the fovea and independent of signal size, mask size, mask contrast, signal and mask font, and number of masks. At 4 deg eccentricity, the threshold contrast for identification of a 0.32 deg signal letter is elevated (up to six-fold) by mask letters anywhere in a 2.3 deg region, 7 times wider than the signal. In ordinary masking, threshold contrast rises as a power function of mask contrast, with a shallow log-log slope of 0.5 to 1, whereas, in crowding, threshold is a sigmoidal function of mask contrast, with a steep log-log slope of 2 at close spacing. Most remarkably, although the threshold elevation decreases exponentially with spacing, the threshold and saturation contrasts of crowding are independent of spacing. Finally, ordinary masking is similar for detection and identification, but crowding occurs only for identification, not detection. More precisely, crowding occurs only in tasks that cannot be done based on a single detection by coarsely coded feature detectors. These results (and observers' introspections) suggest that ordinary masking blocks feature detection, so the signal disappears, while crowding (like "illusory conjunction") is excessive feature integration - detected features are integrated over an inappropriately large area because there are no smaller integration fields - so the integrated signal is ambiguous, jumbled with the mask. In illusory conjunction, observers see an object that is not there made up of features that are. A survey of the illusory conjunction literature finds that most of the illusory conjunction results are consistent with the spatial crowding described here, which depends on spatial proximity, independent of time pressure. The rest seem to arise through a distinct phenomenon that one might call "temporal crowding," which depends on time pressure ("overloading attention"), independent of spatial proximity.
@Article{Pelli2004,
author = {Pelli, Denis G. and Palomares, Melanie and Majaj, Najib J.},
journal = {J Vis},
title = {Crowding is unlike ordinary masking: distinguishing feature integration from detection.},
year = {2004},
number = {12},
pages = {1136--1169},
volume = {4},
abstract = {A letter in the peripheral visual field is much harder to identify
in the presence of nearby letters. This is "crowding." Both crowding
and ordinary masking are special cases of "masking," which, in general,
refers to any effect of a "mask" pattern on the discriminability
of a signal. Here we characterize crowding, and propose a diagnostic
test to distinguish it from ordinary masking. In ordinary masking,
the signal disappears. In crowding, it remains visible, but is ambiguous,
jumbled with its neighbors. Masks are usually effective only if they
overlap the signal, but the crowding effect extends over a large
region. The width of that region is proportional to signal eccentricity
from the fovea and independent of signal size, mask size, mask contrast,
signal and mask font, and number of masks. At 4 deg eccentricity,
the threshold contrast for identification of a 0.32 deg signal letter
is elevated (up to six-fold) by mask letters anywhere in a 2.3 deg
region, 7 times wider than the signal. In ordinary masking, threshold
contrast rises as a power function of mask contrast, with a shallow
log-log slope of 0.5 to 1, whereas, in crowding, threshold is a sigmoidal
function of mask contrast, with a steep log-log slope of 2 at close
spacing. Most remarkably, although the threshold elevation decreases
exponentially with spacing, the threshold and saturation contrasts
of crowding are independent of spacing. Finally, ordinary masking
is similar for detection and identification, but crowding occurs
only for identification, not detection. More precisely, crowding
occurs only in tasks that cannot be done based on a single detection
by coarsely coded feature detectors. These results (and observers'
introspections) suggest that ordinary masking blocks feature detection,
so the signal disappears, while crowding (like "illusory conjunction")
is excessive feature integration - detected features are integrated
over an inappropriately large area because there are no smaller integration
fields - so the integrated signal is ambiguous, jumbled with the
mask. In illusory conjunction, observers see an object that is not
there made up of features that are. A survey of the illusory conjunction
literature finds that most of the illusory conjunction results are
consistent with the spatial crowding described here, which depends
on spatial proximity, independent of time pressure. The rest seem
to arise through a distinct phenomenon that one might call "temporal
crowding," which depends on time pressure ("overloading attention"),
independent of spatial proximity.},
doi = {10:1167/4.12.12},
institution = {Neural Science, New York University, New York, NY, USA. denis.pelli@nyu.edu},
keywords = {Contrast Sensitivity, physiology; Form Perception, physiology; Humans; Perceptual Masking, physiology},
language = {eng},
medline-pst = {epublish},
pmid = {15669917},
timestamp = {2014.01.10},
}
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{"_id":"PQz93dM9SwPp4PAPP","bibbaseid":"pelli-palomares-majaj-crowdingisunlikeordinarymaskingdistinguishingfeatureintegrationfromdetection-2004","author_short":["Pelli, D. G.","Palomares, M.","Majaj, N. J."],"bibdata":{"bibtype":"article","type":"article","author":[{"propositions":[],"lastnames":["Pelli"],"firstnames":["Denis","G."],"suffixes":[]},{"propositions":[],"lastnames":["Palomares"],"firstnames":["Melanie"],"suffixes":[]},{"propositions":[],"lastnames":["Majaj"],"firstnames":["Najib","J."],"suffixes":[]}],"journal":"J Vis","title":"Crowding is unlike ordinary masking: distinguishing feature integration from detection.","year":"2004","number":"12","pages":"1136–1169","volume":"4","abstract":"A letter in the peripheral visual field is much harder to identify in the presence of nearby letters. This is \"crowding.\" Both crowding and ordinary masking are special cases of \"masking,\" which, in general, refers to any effect of a \"mask\" pattern on the discriminability of a signal. Here we characterize crowding, and propose a diagnostic test to distinguish it from ordinary masking. In ordinary masking, the signal disappears. In crowding, it remains visible, but is ambiguous, jumbled with its neighbors. Masks are usually effective only if they overlap the signal, but the crowding effect extends over a large region. The width of that region is proportional to signal eccentricity from the fovea and independent of signal size, mask size, mask contrast, signal and mask font, and number of masks. At 4 deg eccentricity, the threshold contrast for identification of a 0.32 deg signal letter is elevated (up to six-fold) by mask letters anywhere in a 2.3 deg region, 7 times wider than the signal. In ordinary masking, threshold contrast rises as a power function of mask contrast, with a shallow log-log slope of 0.5 to 1, whereas, in crowding, threshold is a sigmoidal function of mask contrast, with a steep log-log slope of 2 at close spacing. Most remarkably, although the threshold elevation decreases exponentially with spacing, the threshold and saturation contrasts of crowding are independent of spacing. Finally, ordinary masking is similar for detection and identification, but crowding occurs only for identification, not detection. More precisely, crowding occurs only in tasks that cannot be done based on a single detection by coarsely coded feature detectors. These results (and observers' introspections) suggest that ordinary masking blocks feature detection, so the signal disappears, while crowding (like \"illusory conjunction\") is excessive feature integration - detected features are integrated over an inappropriately large area because there are no smaller integration fields - so the integrated signal is ambiguous, jumbled with the mask. In illusory conjunction, observers see an object that is not there made up of features that are. A survey of the illusory conjunction literature finds that most of the illusory conjunction results are consistent with the spatial crowding described here, which depends on spatial proximity, independent of time pressure. The rest seem to arise through a distinct phenomenon that one might call \"temporal crowding,\" which depends on time pressure (\"overloading attention\"), independent of spatial proximity.","doi":"10:1167/4.12.12","institution":"Neural Science, New York University, New York, NY, USA. denis.pelli@nyu.edu","keywords":"Contrast Sensitivity, physiology; Form Perception, physiology; Humans; Perceptual Masking, physiology","language":"eng","medline-pst":"epublish","pmid":"15669917","timestamp":"2014.01.10","bibtex":"@Article{Pelli2004,\n author = {Pelli, Denis G. and Palomares, Melanie and Majaj, Najib J.},\n journal = {J Vis},\n title = {Crowding is unlike ordinary masking: distinguishing feature integration from detection.},\n year = {2004},\n number = {12},\n pages = {1136--1169},\n volume = {4},\n abstract = {A letter in the peripheral visual field is much harder to identify\n\tin the presence of nearby letters. This is \"crowding.\" Both crowding\n\tand ordinary masking are special cases of \"masking,\" which, in general,\n\trefers to any effect of a \"mask\" pattern on the discriminability\n\tof a signal. Here we characterize crowding, and propose a diagnostic\n\ttest to distinguish it from ordinary masking. In ordinary masking,\n\tthe signal disappears. In crowding, it remains visible, but is ambiguous,\n\tjumbled with its neighbors. Masks are usually effective only if they\n\toverlap the signal, but the crowding effect extends over a large\n\tregion. The width of that region is proportional to signal eccentricity\n\tfrom the fovea and independent of signal size, mask size, mask contrast,\n\tsignal and mask font, and number of masks. At 4 deg eccentricity,\n\tthe threshold contrast for identification of a 0.32 deg signal letter\n\tis elevated (up to six-fold) by mask letters anywhere in a 2.3 deg\n\tregion, 7 times wider than the signal. In ordinary masking, threshold\n\tcontrast rises as a power function of mask contrast, with a shallow\n\tlog-log slope of 0.5 to 1, whereas, in crowding, threshold is a sigmoidal\n\tfunction of mask contrast, with a steep log-log slope of 2 at close\n\tspacing. Most remarkably, although the threshold elevation decreases\n\texponentially with spacing, the threshold and saturation contrasts\n\tof crowding are independent of spacing. Finally, ordinary masking\n\tis similar for detection and identification, but crowding occurs\n\tonly for identification, not detection. More precisely, crowding\n\toccurs only in tasks that cannot be done based on a single detection\n\tby coarsely coded feature detectors. These results (and observers'\n\tintrospections) suggest that ordinary masking blocks feature detection,\n\tso the signal disappears, while crowding (like \"illusory conjunction\")\n\tis excessive feature integration - detected features are integrated\n\tover an inappropriately large area because there are no smaller integration\n\tfields - so the integrated signal is ambiguous, jumbled with the\n\tmask. In illusory conjunction, observers see an object that is not\n\tthere made up of features that are. A survey of the illusory conjunction\n\tliterature finds that most of the illusory conjunction results are\n\tconsistent with the spatial crowding described here, which depends\n\ton spatial proximity, independent of time pressure. The rest seem\n\tto arise through a distinct phenomenon that one might call \"temporal\n\tcrowding,\" which depends on time pressure (\"overloading attention\"),\n\tindependent of spatial proximity.},\n doi = {10:1167/4.12.12},\n institution = {Neural Science, New York University, New York, NY, USA. denis.pelli@nyu.edu},\n keywords = {Contrast Sensitivity, physiology; Form Perception, physiology; Humans; Perceptual Masking, physiology},\n language = {eng},\n medline-pst = {epublish},\n pmid = {15669917},\n timestamp = {2014.01.10},\n}\n\n","author_short":["Pelli, D. G.","Palomares, M.","Majaj, N. 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