Children's use of visual summary statistics for material categorization

Abstract

Although adults' ability to recognize materials from complex natural images has been well characterized, we still know very little about the development of material perception. When do children exhibit adult-like abilities to categorize materials? What visual features do they use to do so as a function of age and material category? In the present study, we attempted to address both of these issues in two experiments that we administered to school-age children (5–10 years old) and adults. In both tasks, we asked our participants to categorize natural materials (metal, stone, water, and wood) using original images of these materials as well as synthetic images made with the Portilla–Simoncelli algorithm. By including synthetic images in our stimulus set, we were able to assess both how material categorization develops during childhood and how visual summary statistics are recruited for material perception across age groups. We observed that when asked to provide category labels for individual images (Experiment 1), young children were disproportionately bad at categorizing some materials after they were synthesized, suggesting material-specific changes in information use over the course of development. However, when asked to match real and synthetic images according to material category without labeling (Experiment 2), these effects were weakened. We conclude that while children have adult-like abilities to encode and compare images based on summary statistics, the mapping between summary statistics and category labels undergoes prolonged development during childhood.

Neural sensitivity to natural texture statistics in infancy

“…There are conflicting results regarding whether or not infants and children might be sensitive to statistical properties of images like these. School-age children's material categorization suffers when synthetic textures are used (Balas, 2017), suggesting that their visual system is tuned to the natural appearance of materials. However, children in the same age range fail to show the same sensitivity as adults to fractal images that vary in their conformity to natural image statistics (Ellemberg, Hansen, & Johnson, 2012).…”

“…School-age children's material categorization suffers when synthetic textures are used (Balas, 2017), suggesting that their visual system is tuned to the natural appearance of materials. School-age children's material categorization suffers when synthetic textures are used (Balas, 2017), suggesting that their visual system is tuned to the natural appearance of materials.…”

Children's use of local and global visual features for material perception

“…Children do not exhibit adult-like texture discrimination abilities until at least 10 years of age (Ellemberg, Hansen, & Johnson, 2012) and also do not appear to segment textures accurately until late in middle childhood (Sirteneau & Rieth, 1992). In previous work, we have also shown that regarding material perception specifically, some aspects of material categorization are also not adult-like during middle childhood, although this varies by material property (Balas, 2017). A key question regarding this slow development of adult-like abilities is whether or not ongoing improvements in material perception reflect changes in how visual information is used to inform material judgments or more general improvement in the efficiency of processes that support material perception.…”

“…A key question regarding this slow development of adult-like abilities is whether or not ongoing improvements in material perception reflect changes in how visual information is used to inform material judgments or more general improvement in the efficiency of processes that support material perception. In our previous work, we found that forcing children and adults to use visual summary statistics (Balas, 2006;Balas, Nakano, & Rosenholtz, 2009) to assess material properties affected categorization, but not matching, performance differently as a function of age (Balas, 2017). We interpreted these results as evidence that children had more or less adult-like abilities to compare and match materials using the information available in "mongrels" made from natural material images but had not yet established robust mappings between those features and category labels.…”

Neural Sensitivity to Natural Image Statistics Changes during Middle Childhood

“…Critically, though there are more recent models that make it possible to match synthetic textures to their parent images more closely with regard to these higher-order structural features, the absence of this matching using simpler models makes it possible to examine how adult visual processing is affected by the absence of these relationships from natural images. In general, removing these statistical regularities from natural images incurs a measurable cost in a range of tasks including invariant texture matching (Balas & Conlin, 2015a) and material categorization (Balas & Schmidt, 2017). Moreover, observers' ability to distinguish between putative "scene metamers" that are defined by matching parametric texture features like those described above (Freeman & Simoncelli, 2011;Wallis, Bethge & Wichmann, 2016) suggests that the adult visual system is sensitive to the absence of higher-order statistical regularities that are absent from synthetic images rendered via these models.…”