Investigating the interaction between low and intermediate levels of spatial vision at different periods of development

Abstract

Although much research has investigated the visual development of lower (local) and higher levels (global) of processing in isolation, less is known about the developmental interactions between mechanisms mediating early- and intermediate-level vision. The objective of this study was to evaluate the development of intermediate-level vision by assessing the ability to discriminate circular shapes (global) whose contour was defined by different local attributes: luminance and texture. School-aged children, adolescents, and adults were asked to discriminate a deformed circle (radial frequency patterns or RFP) from a circle. RFPs varied as a function of (a) number of bumps or curvatures (radial frequency of three, five, and 10) and (b) the physical attribute (luminance or texture) that defined the contour. Deformation thresholds were measured for each radial frequency and attribute condition. In general, results indicated that when compared to adolescents and adults children performed worse only when luminance-defined shapes had fewer curvatures (i.e., three and five), but for texture-defined shapes, children performed worse across all types of radial frequencies (three, five, and 10). This suggests that sensitivity to global shapes mediated by intermediate level vision is differentially affected by the type of local information defining the global shape at different periods of development.

Dissociation of local and global contributions to detection of shape with age.

“…Our method allows the dissociation of sensitivity to local contour deformations from the integration of that information and the results lead to the suggestion that sensitivity to the local features of the RF contour such as curvature information is, instead, improving as a function of age. This is contrary to the conclusions of Perreault et al (2013), whose data suggested global processing was not yet mature in primary school-age children but that sensitivity to local contour information was mature in this age group. The authors reached this conclusion on the basis that children were less sensitive to fully modulated RF3 and RF5 patterns (globally processed frequencies) than adults, but groups were equally sensitive to a fully modulated RF10 (a locally processed frequency).…”

“…The data indicate that all participants showed improvements in threshold as more cycles of deformation were added and the improvements were larger than those predicted by probability summation (using either method for this calculation), indicating global contour integration is occurring and that it occurs at all ages. The data suggest sensitivity to deformation in globally processed RF patterns improves from primary school age to early adulthood for samples whose cognitive ability is in the normal range, consistent with data reported by Wang et al (2009) and Perreault et al (2013). However, these changes in sensitivity to RF patterns across development cannot be accounted for by increased effectiveness of global contour integration, as our data suggests there is no improvement in the steepness of integration slopes across this period of development.…”

“…Two studies have investigated how sensitivity to fully modulated RF patterns improves across development but neither have dissociated local contour processing stages from global integration stages of shape processing. Both of these studies reported that primary school aged children (aged 7-12) are less sensitive to deformation in complete RF patterns than adults (Perreault et al, 2013;Wang et al, 2009), suggesting that one or more visual processes involved in detection of these patterns is still maturing within this age range. Wang et al (2009) tested a total of 236 observers aged 0.25-78 years, concluding that thresholds did not reach the adult mean until age 21, but that some children had sensitivity in the adult range by age 7.…”

“…Following the early processes that detect the properties of the local contour elements, such as position, contrast polarity, orientation, and width, comes a second stage, which globally pools curvature features around shapes (Loffler, 2015; Wilson & Wilkinson, 2014). This property of contour processing has been proposed following a range of studies on adult expert psychophysical observers but may also be dissociable through differential changes with age (Perreault, Habak, Lepore, & Bertone, 2013; Wang, Morale, Cousins, & Birch, 2009). Radial Frequency (RF) patterns (Wilkinson, Wilson, & Habak, 1998) are a stimulus class that has been employed to measure the ability to integrate curvature information around contours.…”

“…Two metrics of performance can be derived from their use: sensitivity to local curvature information, and ability to integrate this information together to form a global percept of shape (Almeida, Dickinson, Maybery, Badcock, & Badcock, 2014). Previous studies (Perreault et al, 2013;Wang et al, 2009) have found children are less sensitive to shape changes in RF patterns than adults; however, these studies did not differentiate between aspects of performance driven by detection of the local contour features and those reflecting the ability to pool this information around the contour. In the present study, we ask whether these two stages of processing are separable by monitoring how both change with chronological age.…”