Abstract:
Different components of visual perception such as spatial frequency (SF) detection, luminance contrast sensitivity and colour vision develop at different rates. At 5-6 years of age, High SF (HSF) sensitivity is nearly adult-like and luminance contrast is also nearing the end of its maturation around 5-7 years. Low SF (LSF) on the other hand still has a substantial development to undergo till the age of 12. Additionally, there is a shift in selective processing of SF from the N2 component of visual evoked potential (VEP) in 3-6 year olds to the earlier N80 component of VEP at ages 7-8. Adult literature has revealed a complex interaction between SF and luminance contrast. How this interaction takes form in children however is relatively unknown. The aim of this study is to investigate the interaction between spatial frequency and luminance contrast in 5-6 year olds when these different components of visual perception are at different developmental stages to gain more insight into how this interaction develops. VEP modulations of HSF/LSF gratings at high and low luminance contrast levels were measured with electroencephalography (EEG) in 22 children aged 5. Results show that the P1 peak shows an adult-like pattern in 5 year olds, with an increase in amplitude as contrast increases, irrespective of SF. The N80 peak however shows only partial resemblance to the adult VEPs, showing the same selective enhanced activity for HSF but not LSF, yet is still lacking the interaction with contrast. Contrarily the N2 peak closely resembles the interactions patterns found for the N80 peak in adults. Taken together, the argument can be made that the complex interaction between SF and Contrast is characteristic for the selective processing of HSF and LSF stimuli and that the interaction between spatial frequency and contrast depends on the maturity of the underlying systems.
