Perceived velocity of luminance, chromatic and non-Fourier stimuli: Influence of contrast and temporal frequency

Karl R. Gegenfurtner, Michael Hawken

Research output: Contribution to journalArticle

Abstract

We measured perceived velocity as a function of contrast for luminance and isoluminant sinusoidal gratings, luminance and isoluminant plaids, and second-order, amplitude-modulated, drift-balanced stimuli. For all types of stimuli perceived velocity was contrast-invariant for fast moving patterns at or above 4 deg/sec. For slowly moving stimuli the log of perceived velocity was a linear function of the log of the contrast. The slope of this perceived velocity-vs-contrast line (velocity gain) was relatively shallow for luminance gratings and luminance plaids, but was steep for isoluminant gratings and isoluminant plaids, as well as for drift-balanced stimuli. Independent variation of spatial and temporal frequency showed that these variables, and not velocity alone, determine the velocity gain. Overall, the results indicate that slow moving stimuli defined by chromaticity or by second-order statistics are processed in a different manner from luminance defined stimuli. We propose that there are a number of independent mechanisms processing motion targets and it is the interplay of these mechanisms that is responsible for the final percept.

Original languageEnglish (US)
Pages (from-to)1281-1290
Number of pages10
JournalVision Research
Volume36
Issue number9
DOIs
StatePublished - May 1996

Fingerprint

Color

Keywords

  • Color
  • Isoluminance
  • Motion
  • Velocity

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

Cite this

Perceived velocity of luminance, chromatic and non-Fourier stimuli : Influence of contrast and temporal frequency. / Gegenfurtner, Karl R.; Hawken, Michael.

In: Vision Research, Vol. 36, No. 9, 05.1996, p. 1281-1290.

Research output: Contribution to journalArticle

@article{89e6287f2f744f5bb03cbb92acab5896,
title = "Perceived velocity of luminance, chromatic and non-Fourier stimuli: Influence of contrast and temporal frequency",
abstract = "We measured perceived velocity as a function of contrast for luminance and isoluminant sinusoidal gratings, luminance and isoluminant plaids, and second-order, amplitude-modulated, drift-balanced stimuli. For all types of stimuli perceived velocity was contrast-invariant for fast moving patterns at or above 4 deg/sec. For slowly moving stimuli the log of perceived velocity was a linear function of the log of the contrast. The slope of this perceived velocity-vs-contrast line (velocity gain) was relatively shallow for luminance gratings and luminance plaids, but was steep for isoluminant gratings and isoluminant plaids, as well as for drift-balanced stimuli. Independent variation of spatial and temporal frequency showed that these variables, and not velocity alone, determine the velocity gain. Overall, the results indicate that slow moving stimuli defined by chromaticity or by second-order statistics are processed in a different manner from luminance defined stimuli. We propose that there are a number of independent mechanisms processing motion targets and it is the interplay of these mechanisms that is responsible for the final percept.",
keywords = "Color, Isoluminance, Motion, Velocity",
author = "Gegenfurtner, {Karl R.} and Michael Hawken",
year = "1996",
month = "5",
doi = "10.1016/0042-6989(95)00198-0",
language = "English (US)",
volume = "36",
pages = "1281--1290",
journal = "Vision Research",
issn = "0042-6989",
publisher = "Elsevier Limited",
number = "9",

}

TY - JOUR

T1 - Perceived velocity of luminance, chromatic and non-Fourier stimuli

T2 - Influence of contrast and temporal frequency

AU - Gegenfurtner, Karl R.

AU - Hawken, Michael

PY - 1996/5

Y1 - 1996/5

N2 - We measured perceived velocity as a function of contrast for luminance and isoluminant sinusoidal gratings, luminance and isoluminant plaids, and second-order, amplitude-modulated, drift-balanced stimuli. For all types of stimuli perceived velocity was contrast-invariant for fast moving patterns at or above 4 deg/sec. For slowly moving stimuli the log of perceived velocity was a linear function of the log of the contrast. The slope of this perceived velocity-vs-contrast line (velocity gain) was relatively shallow for luminance gratings and luminance plaids, but was steep for isoluminant gratings and isoluminant plaids, as well as for drift-balanced stimuli. Independent variation of spatial and temporal frequency showed that these variables, and not velocity alone, determine the velocity gain. Overall, the results indicate that slow moving stimuli defined by chromaticity or by second-order statistics are processed in a different manner from luminance defined stimuli. We propose that there are a number of independent mechanisms processing motion targets and it is the interplay of these mechanisms that is responsible for the final percept.

AB - We measured perceived velocity as a function of contrast for luminance and isoluminant sinusoidal gratings, luminance and isoluminant plaids, and second-order, amplitude-modulated, drift-balanced stimuli. For all types of stimuli perceived velocity was contrast-invariant for fast moving patterns at or above 4 deg/sec. For slowly moving stimuli the log of perceived velocity was a linear function of the log of the contrast. The slope of this perceived velocity-vs-contrast line (velocity gain) was relatively shallow for luminance gratings and luminance plaids, but was steep for isoluminant gratings and isoluminant plaids, as well as for drift-balanced stimuli. Independent variation of spatial and temporal frequency showed that these variables, and not velocity alone, determine the velocity gain. Overall, the results indicate that slow moving stimuli defined by chromaticity or by second-order statistics are processed in a different manner from luminance defined stimuli. We propose that there are a number of independent mechanisms processing motion targets and it is the interplay of these mechanisms that is responsible for the final percept.

KW - Color

KW - Isoluminance

KW - Motion

KW - Velocity

UR - http://www.scopus.com/inward/record.url?scp=0029869681&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029869681&partnerID=8YFLogxK

U2 - 10.1016/0042-6989(95)00198-0

DO - 10.1016/0042-6989(95)00198-0

M3 - Article

VL - 36

SP - 1281

EP - 1290

JO - Vision Research

JF - Vision Research

SN - 0042-6989

IS - 9

ER -