The Effect of Displacement on Sensitivity to First- and Second-Order Global Motion in 5-year-olds and Adults

We compared the development of sensitivity to first- versus second-order global motion in 5-year-olds (n=24) and adults (n=24) tested at three displacements (0.1, 0.5 and 1.0 degrees). Sensitivity was measured with Random-Gabor Kinematograms (RGKs) formed with luminance-modulated (first-order) or contrast-modulated (second-order) concentric Gabor patterns. Five-year-olds were less sensitive than adults to the direction of both first- and second-order global motion at every displacement tested. In addition, the immaturity was smallest at the smallest displacement, which required the least spatial integration, and smaller for first-order than for second-order global motion at the middle displacement. The findings suggest that the development of sensitivity to global motion is limited by the development of spatial integration and by different rates of development of sensitivity to first- versus second-order signals.