Purchase this article with an account.
Dave Ellemberg, Mathilde St-Louis Deschenes, Annie Baillargeon, Elise LeMoyne, Samuel St-Jacques; Developmental Processes Underlying Orientation Discrimination During Childhood. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4801.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Orientation-selectivity is critical for higher-level visual processes from edge extraction to the perception of natural images. Only a few studies documented the development of orientation discrimination, and developmental changes in performance are practically unexplored. The goal of the present study was to chart the development of orientation discrimination during childhood as a function of contrast, spatial frequency, and orientation noise to understand the changes in its underlying mechanisms during development.
Stimuli were circular two-dimensional luminance Gaussian noise with a diameter of 5 degrees. The noise was filtered in the Fourier domain with an anisotropic filter. Orientation discrimination thresholds were determined by means of a one-interval forced choice paradigm combined with an adaptive staircase. Participants had to decide whether the grating was tilted to the left or right of vertical.
Six-year-olds are about 3.5 times less sensitive than adults at low (1 cpd) and mid (4 cpd) range spatial frequencies and they are 4.6 times less sensitive than adults at higher (12 cpd) spatial frequencies. Eight-year-olds are still less sensitive than adults by a 2-fold, and that equally so for each spatial frequency. Orientation discrimination is adult-like at 10 years of age for all conditions tested, falling within the range of 0.5 to 1.0 degree. Orientation discrimination is contrast invariant in children when tested with low (1 cpd) to mid range (4 cpd) spatial frequencies that have a contrast equal to or greater than 25%. However, thresholds increase by a factor of two for a spatial frequency of 12 cpd presented at a contrast of 25%. The introduction of orientation noise increases discrimination thresholds for each age group, but significantly more so for the 6- and 8-year-old children.
Orientation discrimination matures slowly during childhood and it is influenced by spatial frequency and contrast. Because internal noise explains much of the functional immaturity in children, the main source of developmental variation in orientation discrimination most likely occurs at the initial stages of feature coding.
This PDF is available to Subscribers Only