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Single target acuity is not higher than grating acuity in a bird, the budgerigar

Chaib, Sandra LU ; Ljungholm, Mikael LU ; Lind, Olle LU and Kelber, Almut LU (2019) In Vision Research 160. p.37-42
Abstract


We examined the capacity of budgerigars (Melopsittacus undulatus)to visually detect dark single targets against a brighter background and established their spatial resolution limit for such targets. While the sampling density of the retina limits the resolution of gratings, target detection is theoretically limited by contrast sensitivity. This allows many animals to detect single targets smaller than their visual resolution limit, but this is not the case for budgerigars. The budgerigars were able to detect a high contrast circular target with a luminance profile of a single period of a sine wave subtending 0.065 degrees of their visual field, corresponding to a spatial... (More)


We examined the capacity of budgerigars (Melopsittacus undulatus)to visually detect dark single targets against a brighter background and established their spatial resolution limit for such targets. While the sampling density of the retina limits the resolution of gratings, target detection is theoretically limited by contrast sensitivity. This allows many animals to detect single targets smaller than their visual resolution limit, but this is not the case for budgerigars. The budgerigars were able to detect a high contrast circular target with a luminance profile of a single period of a sine wave subtending 0.065 degrees of their visual field, corresponding to a spatial acuity of 7.7 cycles degree
−1
, a measurement in line with the previously measured grating acuity of budgerigars (7.7 and 10 cycles degree
−1
). This result is different from findings on the spatial acuity of humans, who can detect single targets much smaller than predicted by their acuity for gratings. The low contrast sensitivity of budgerigar vision might be one of the reasons why the single target acuity is not higher than grating acuity. Adding a bright surround to the target did not influence detection threshold significantly. However, the threshold was slightly higher for a target with a square-wave luminance profile than for a target with a sinusoidal luminance profile.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bird vision, Contrast sensitivity, Spatial resolution, Target acuity, Target detection, Visual acuity
in
Vision Research
volume
160
pages
6 pages
publisher
Elsevier
external identifiers
  • scopus:85065540686
ISSN
0042-6989
DOI
10.1016/j.visres.2019.04.005
language
English
LU publication?
yes
id
0bdba07e-ad61-41ab-8461-c5c0bc5a145c
date added to LUP
2019-05-22 09:56:39
date last changed
2019-06-19 04:13:04
@article{0bdba07e-ad61-41ab-8461-c5c0bc5a145c,
  abstract     = {<p><br>
                                                         We examined the capacity of budgerigars (Melopsittacus undulatus)to visually detect dark single targets against a brighter background and established their spatial resolution limit for such targets. While the sampling density of the retina limits the resolution of gratings, target detection is theoretically limited by contrast sensitivity. This allows many animals to detect single targets smaller than their visual resolution limit, but this is not the case for budgerigars. The budgerigars were able to detect a high contrast circular target with a luminance profile of a single period of a sine wave subtending 0.065 degrees of their visual field, corresponding to a spatial acuity of 7.7 cycles degree                             <br>
                            <sup>−1</sup><br>
                                                         , a measurement in line with the previously measured grating acuity of budgerigars (7.7 and 10 cycles degree                             <br>
                            <sup>−1</sup><br>
                                                         ). This result is different from findings on the spatial acuity of humans, who can detect single targets much smaller than predicted by their acuity for gratings. The low contrast sensitivity of budgerigar vision might be one of the reasons why the single target acuity is not higher than grating acuity. Adding a bright surround to the target did not influence detection threshold significantly. However, the threshold was slightly higher for a target with a square-wave luminance profile than for a target with a sinusoidal luminance profile.                         <br>
                        </p>},
  author       = {Chaib, Sandra and Ljungholm, Mikael and Lind, Olle and Kelber, Almut},
  issn         = {0042-6989},
  keyword      = {Bird vision,Contrast sensitivity,Spatial resolution,Target acuity,Target detection,Visual acuity},
  language     = {eng},
  pages        = {37--42},
  publisher    = {Elsevier},
  series       = {Vision Research},
  title        = {Single target acuity is not higher than grating acuity in a bird, the budgerigar},
  url          = {http://dx.doi.org/10.1016/j.visres.2019.04.005},
  volume       = {160},
  year         = {2019},
}