Development of visual texture segregation during early childhood

Abstract

Most of the studies that have focused on the development of the visual system in children using visual evoked potentials (VEPs) have used stimuli soliciting only one level of visual processing. However, the perception of a visual scene requires a multitude of analytical processes ranging from the encoding of various characteristics of the visual stimuli, to the processing of top-down information and finally leading to segmentation of forms and recognition of stimuli. Numerous studies have shown that this more complex visual process can be objectively studied with specific VEPs, namely texture segregation visual evoked potentials (tsPEVs). Even though it has been demonstrated that texture segregation appears in the first few months of life and that it continues to develop within the first year, it is not known at what age texture segregation processes reach maturity. The purpose of the present study was to determine, using tsVEPs and high-density EEG, the normal development of higher-level visual processing during early childhood. We assessed typically developing children aged 12 months (n=15), 24 months (n=14) and 36 months of age (n=15). Four different stimuli, two low-level (lines homogeneously oriented to the right or left) and two higher-level (orientation-defined checkerboard composed of 90° line gradients oriented concentrically or outwards) were presented randomly on a screen in front of the child. The tsVEP was obtained by subtracting low-level from higher-level responses. Results show significant (p<.05) differences between the 12 months and 36 months groups, for both amplitude and latency of the N2 component. More specifically, there is a latency reduction and amplitude gain with increasing age. Furthermore, the electrophysiological response pattern obtained at 36 months is comparable to the one observed in adults. In conclusion, our data show that there is a clear maturation of texture-segregation processes taking place between 12 and 36 months of age.

Meeting abstract presented at VSS 2012