The effects of spatial proximity and collinearity on contour integration in adults and children

Abstract

We tested adults and children aged 7 and 14 on the ability to integrate contour elements across variations in the collinearity of the target elements, their spatial proximity, and the relative spacing of the target elements to the background noise elements (Delta). When collinearity was high, the strength of integration for adults was largely independent of spatial proximity and varied only with Delta. It was only when collinearity was less reliable because the orientation of the elements was randomly jittered that spatial proximity began to influence adults' integration. These patterns correspond well to the probability that real-world contours compose a single object: collinear elements are more likely to reflect parts of a real object and adults integrate them easily regardless of the proximity among those collinear elements. The results from children demonstrate a gradual improvement of contour integration throughout childhood and the slow development of sensitivity to the statistics of natural scenes. Unlike adults, integration in children was limited by spatial proximity regardless of collinearity and one strong cue did not compensate for the other. Only after age 14 did collinearity, the most reliable cue, come to compensate efficiently for spatial proximity.

Gradual improvement in fine-grained sensitivity to triadic gaze after 6 years of age

“…The 8-year-olds required a much greater mismatch in the direction of gaze than the adults to reliably detect the mismatch. This is consistent with findings that children in this age range are less sensitive than adults in making other judgments about spatial relations in both faces and non-face stimuli (Baudouin et al, 2010;Hadad, Maurer, & Lewis, 2010a;Hadad, Maurer, & Lewis, 2010b).…”

Developmental trends in interpolation and its spatial constraints: A comparison of subjective and occluded contours

“…The effect shown here of contour geometry on interpolation in young childhood is in agreement with the effect of spatial distances shown in contour integration studies (Kovacs et al, 1999;Hadad et al 2010aHadad et al , 2010b. Both interpolation in the cases of subjective and occluded contours and integration of fragmented elements into a contour is critically restricted during childhood by the spatial distance over which this perceptual process is employed, with both cases of contour perception extending over nearly the same spatial distances.…”

“…This local mechanism is strongly governed by contour relatability, such that contours that are smooth and monotonic, and at their endpoints match the slopes of real contours, are more readily interpolated (Kellman & Shipley, 1991). Given this critical role of relatability, some tolerance around collinearity early in life, with gradual decrease in this tolerance as perceptual experience accrues (Hadad et al, 2010b), might underlie the agerelated changes in interpretation observed here.…”

“…Consistent with this suggestion, the two different literatures demonstrate similar restrictions of contour geometry and scale-dependence of these perceptual mechanisms. In both cases, for example, it has been shown that the mature mechanism in adults is tied more to scale-invariant factors (e.g., Shipley & Kellman, 1992;Sigman, Cecchi, Gilbert, & Magnasco, 2001) and the developing mechanism spans shorter spatial distances compared to those in adults (e.g., Kovács, 2000;Hadad, Maurer, & Lewis, 2010b). These psychophysical findings have been steadily gaining neurophysiological support.…”

“…A full description of this procedure is presented in Hadad et al (2010aHadad et al ( , 2010b. Briefly, demonstration consisted of two trials, one with the fat and the other with the skinny shape, with 10°rotations of the inducers employed in each.…”