Empirical Inference Article 2007

Some observations on the pedestal effect

The pedestal or dipper effect is the large improvement in the detectability of a sinusoidal grating observed when it is added to a masking or pedestal grating of the same spatial frequency, orientation, and phase. We measured the pedestal effect in both broadband and notched noiseVnoise from which a 1.5-octave band centered on the signal frequency had been removed. Although the pedestal effect persists in broadband noise, it almost disappears in the notched noise. Furthermore, the pedestal effect is substantial when either high- or low-pass masking noise is used. We conclude that the pedestal effect in the absence of notched noise results principally from the use of information derived from channels with peak sensitivities at spatial frequencies different from that of the signal and the pedestal. We speculate that the spatial-frequency components of the notched noise above and below the spatial frequency of the signal and the pedestal prevent ‘‘off-frequency looking,’’ that is, prevent the use of information about changes in contrast carried in channels tuned to spatial frequencies that are very much different from that of the signal and the pedestal. Thus, the pedestal or dipper effect measured without notched noise appears not to be a characteristic of individual spatial-frequency-tuned channels.

Author(s): Henning, GB. and Wichmann, FA.
Journal: Journal of Vision
Volume: 7
Number (issue): 1:3
Pages: 1-15
Year: 2007
Month: January
Day: 0
Bibtex Type: Article (article)
DOI: 10.1167/7.1.3
Digital: 0
Electronic Archiving: grant_archive
Language: en
Organization: Max-Planck-Gesellschaft
School: Biologische Kybernetik
Links:

BibTex

@article{2375,
  title = {Some observations on the pedestal effect},
  journal = {Journal of Vision},
  abstract = {The pedestal or dipper effect is the large improvement in the detectability of a sinusoidal grating observed when it is added
  to a masking or pedestal grating of the same spatial frequency, orientation, and phase. We measured the pedestal effect
  in both broadband and notched noiseVnoise from which a 1.5-octave band centered on the signal frequency had been
  removed. Although the pedestal effect persists in broadband noise, it almost disappears in the notched noise. Furthermore,
  the pedestal effect is substantial when either high- or low-pass masking noise is used. We conclude that the pedestal effect
  in the absence of notched noise results principally from the use of information derived from channels with peak sensitivities
  at spatial frequencies different from that of the signal and the pedestal. We speculate that the spatial-frequency components
  of the notched noise above and below the spatial frequency of the signal and the pedestal prevent ‘‘off-frequency looking,’’
  that is, prevent the use of information about changes in contrast carried in channels tuned to spatial frequencies that are
  very much different from that of the signal and the pedestal. Thus, the pedestal or dipper effect measured without notched
  noise appears not to be a characteristic of individual spatial-frequency-tuned channels.},
  volume = {7},
  number = {1:3},
  pages = {1-15},
  organization = {Max-Planck-Gesellschaft},
  school = {Biologische Kybernetik},
  month = jan,
  year = {2007},
  slug = {2375},
  author = {Henning, GB. and Wichmann, FA.},
  month_numeric = {1}
}