Abstract
In the only study measuring sensitivity to orientation during childhood, we showed that 5-year-olds are four times worse than adults when tested with high contrast gratings (Lewis, et al., 2007). Here, we tested older children to chart the development of sensitivity to orientation between 5 years and adulthood. Methods. We measured orientation discrimination in 20 7-year-olds (+/− 3 months) and 20 9-year-olds (+/− 3 months) using methods identical to those used previously with 5-year-olds and adults (Lewis, et al., 2007). The stimuli consisted of 1 cpd black-and-white high contrast sine-wave gratings within a 10° circular aperture. The task on each trial was to indicate whether the top of the stripes was tilted to the left or right of vertical. Tilt was varied over trials according to a ML-PEST staircase procedure (Harvey, 1986) to measure the minimum tilt discriminable from vertical. Results. Minimum discriminable tilt improved with age (p ps ps [[gt]] 0.30). The data were best fit by an exponential function (r2= 0.35, p Conclusions. The pattern of development for sensitivity to orientation (this study) resembles those for the development of sensitivity to spatial frequency (Patel, et al., 2009) and contrast (Ellemberg et al, 1999). These similar patterns are consistent with theories of common underlying mechanisms (Vincent & Regan, 1995; Shapely et al., 2003). The immaturities at 5 years of age may be caused by higher internal noise.
Support: Canadian Institutes of Health Research grant # MOP-36430.