title: The Stereoscopic Anisotropy Develops During Childhood.
abstract: OBJECTIVE
  Human vision has a puzzling stereoscopic anisotropy: horizontal depth corrugations are easier to detect than vertical depth corrugations. To date, little is known about the function or the underlying mechanism responsible for this anisotropy. Here, we aim to find out whether this anisotropy is independent of age. To answer this, we compare detection thresholds for horizontal and vertical depth corrugations as a function of age.
  
  
  METHODS
  The depth corrugations were defined solely by the horizontal disparity of random dot patterns. The disparities depicted a horizontal or vertical sinusoidal depth corrugation of spatial frequency 0.1 cyc/deg. Detection thresholds were obtained using Bayesian adaptive staircases from a total of 159 subjects aged from 3 to 73 years. For each participant we computed the anisotropy index, defined as the log10-ratio of the detection threshold for vertical corrugations divided by that for horizontal.
  
  
  RESULTS
  Anisotropy index was highly variable between individuals but was positive in 87% of the participants. There was a significant correlation between anisotropy index and log-age (r = 0.21, P = 0.008) mainly driven by a significant difference between children and adults. In 67 children aged 3 to 13 years, the mean anisotropy index was 0.34 ± 0.38 (mean ± SD, meaning that vertical thresholds were on average 2.2 times the horizontal ones), compared with 0.59 ± 0.55 in 84 adults aged 18 to 73 years (vertical 3.9 times horizontal). This was mainly driven by a decline in the sensitivity to vertical corrugations. Children had poorer stereoacuity than adults, but had similar sensitivity to adults for horizontal corrugations and were actually more sensitive than adults to vertical corrugations.
  
  
  CONCLUSIONS
  The fact that adults show stronger stereo anisotropy than children raises the possibility that visual experience plays a critical role in developing and strengthening the stereo anisotropy.
authors.affiliation: Facultad de Psicología Universidad Complutense de Madrid Campus de Somosaguas, Madrid, Spain 2Institute of Neuroscience, Henry Wellcome Building, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Serrano-Pedraza
authors.affiliation: Institute of Neuroscience, Henry Wellcome Building, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: Herbert
authors.affiliation: Universidad Internacional de La Rioja, La Rioja, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Villa-Laso
authors.affiliation: Institute of Neuroscience, Henry Wellcome Building, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Widdall
authors.affiliation: Institute of Neuroscience, Henry Wellcome Building, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Vancleef
authors.affiliation: Institute of Neuroscience, Henry Wellcome Building, Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom.
authors.forename: Jenny C A
authors.initials: JC
authors.lastname: Read
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016880:Anisotropy; D002648:Child; D002675:Child, Preschool; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D015357:Vision Disparity / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*; D055815:Young Adult