Scale dependence and channel switching in letter identification

Ipek Oruç, Michael Landy

Research output: Contribution to journalArticle

Abstract

Letters are broadband visual stimuli with information useful for discrimination over a wide range of spatial frequencies. Yet, recent evidence suggests that observers use only a single, fixed spatial-frequency channel to identify letters and that the scale of that channel, in units of letter size, is determined by the size of the letter (scale dependence). We report two letter-identification experiments using critical-band masking. With sufficiently high-amplitude, low- or high-pass masking noise, observers switched to a different range of spatial frequencies for the task. Thus, letter channels are not fixed for a given letter size. When an additional white-noise masker was added to the stimulus to flatten the contrast-sensitivity function, the letter channel used by the observer still depended on letter size, further supporting the hypothesis that letter identification is scale dependent.

Original languageEnglish (US)
Article number4
JournalJournal of vision
Volume9
Issue number9
DOIs
StatePublished - Aug 13 2009

Fingerprint

Contrast Sensitivity
Noise
Discrimination (Psychology)

Keywords

  • Channel switching
  • Critical-band masking
  • Equivalent input noise
  • Ideal observer
  • Letter channels
  • Letter identification
  • Scale invariance

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

Cite this

Scale dependence and channel switching in letter identification. / Oruç, Ipek; Landy, Michael.

In: Journal of vision, Vol. 9, No. 9, 4, 13.08.2009.

Research output: Contribution to journalArticle

@article{2258f6bbe4e341748cafed6d3bdc68a6,
title = "Scale dependence and channel switching in letter identification",
abstract = "Letters are broadband visual stimuli with information useful for discrimination over a wide range of spatial frequencies. Yet, recent evidence suggests that observers use only a single, fixed spatial-frequency channel to identify letters and that the scale of that channel, in units of letter size, is determined by the size of the letter (scale dependence). We report two letter-identification experiments using critical-band masking. With sufficiently high-amplitude, low- or high-pass masking noise, observers switched to a different range of spatial frequencies for the task. Thus, letter channels are not fixed for a given letter size. When an additional white-noise masker was added to the stimulus to flatten the contrast-sensitivity function, the letter channel used by the observer still depended on letter size, further supporting the hypothesis that letter identification is scale dependent.",
keywords = "Channel switching, Critical-band masking, Equivalent input noise, Ideal observer, Letter channels, Letter identification, Scale invariance",
author = "Ipek Oru{\cc} and Michael Landy",
year = "2009",
month = "8",
day = "13",
doi = "10.1167/9.9.4",
language = "English (US)",
volume = "9",
journal = "Journal of vision",
issn = "1534-7362",
number = "9",

}

TY - JOUR

T1 - Scale dependence and channel switching in letter identification

AU - Oruç, Ipek

AU - Landy, Michael

PY - 2009/8/13

Y1 - 2009/8/13

N2 - Letters are broadband visual stimuli with information useful for discrimination over a wide range of spatial frequencies. Yet, recent evidence suggests that observers use only a single, fixed spatial-frequency channel to identify letters and that the scale of that channel, in units of letter size, is determined by the size of the letter (scale dependence). We report two letter-identification experiments using critical-band masking. With sufficiently high-amplitude, low- or high-pass masking noise, observers switched to a different range of spatial frequencies for the task. Thus, letter channels are not fixed for a given letter size. When an additional white-noise masker was added to the stimulus to flatten the contrast-sensitivity function, the letter channel used by the observer still depended on letter size, further supporting the hypothesis that letter identification is scale dependent.

AB - Letters are broadband visual stimuli with information useful for discrimination over a wide range of spatial frequencies. Yet, recent evidence suggests that observers use only a single, fixed spatial-frequency channel to identify letters and that the scale of that channel, in units of letter size, is determined by the size of the letter (scale dependence). We report two letter-identification experiments using critical-band masking. With sufficiently high-amplitude, low- or high-pass masking noise, observers switched to a different range of spatial frequencies for the task. Thus, letter channels are not fixed for a given letter size. When an additional white-noise masker was added to the stimulus to flatten the contrast-sensitivity function, the letter channel used by the observer still depended on letter size, further supporting the hypothesis that letter identification is scale dependent.

KW - Channel switching

KW - Critical-band masking

KW - Equivalent input noise

KW - Ideal observer

KW - Letter channels

KW - Letter identification

KW - Scale invariance

UR - http://www.scopus.com/inward/record.url?scp=69449102511&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=69449102511&partnerID=8YFLogxK

U2 - 10.1167/9.9.4

DO - 10.1167/9.9.4

M3 - Article

VL - 9

JO - Journal of vision

JF - Journal of vision

SN - 1534-7362

IS - 9

M1 - 4

ER -