Showing papers by "Karin H. James published in 2014"

Young Children's Self-Generated Object Views and Object Recognition

Abstract: Two important and related developments in children between 18 and 24 months of age are the rapid expansion of object name vocabularies and the emergence of an ability to recognize objects from sparse representations of their geometric shapes. In the same period, children also begin to show a preference for planar views (i.e., views of objects held perpendicular to the line of sight) of objects they manually explore. Are children's emerging view preferences somehow related to contemporary changes in object name vocabulary and object perception? Children aged 18 to 24 months old explored richly detailed toy objects while wearing a head camera that recorded their object views. Both children's vocabulary size and their success in recognizing sparse three-dimensional representations of the geometric shapes of objects were significantly related to their spontaneous choice of planar views of those objects during exploration. The results suggest important interdependencies among developmental changes in perceptio...

Some views are better than others: evidence for a visual bias in object views self-generated by toddlers.

Abstract: How objects are held determines how they are seen, and may thereby play an important developmental role in building visual object representations. Previous research suggests that toddlers, like adults, show themselves a disproportionate number of planar object views – that is, views in which the objects’ axes of elongation are perpendicular or parallel to the line of sight. Here, three experiments address three explanations of this bias: (1) that the locations of interesting features of objects determine how they are held and thus how they are viewed; (2) that ease of holding determines object views; and (3) that there is a visual bias for planar views that exists independently of holding and of interesting surface properties. Children 18 to 24 months of age manually and visually explored novel objects (1) with interesting features centered in planar or ¾ views; (2) positioned inside Plexiglas boxes so that holding biased either planar or non-planar views; and (3) positioned inside Plexiglas spheres, so that no object properties directly influenced holding. Results indicate a visual bias for planar views that is influenced by interesting surface properties and ease of holding, but that continues to exist even when these factors push for alternative views.

Main axis of elongation dynamics and the planar bias in active object inspection: a developmental approach

Abstract: Poster apresentado em "Leuven Christmas Applied Vision Association (AVA) Conference", em Leuven, Belgica, 2014.

Morphological shape analysis of children's actively generated viewpoints

Abstract: Our visual system develops in a world of three-dimensional objects, where the dynamic visual experience of objects is often under the child’s active control. Previous experimental work by some of us was the first to analyze in detail what kind of object views are selected in children’s unconstrained manipulation of physical objects (Pereira, James, Jones, & Smith, 2010). The key finding was the distribution of dwell time across all possible viewpoints: preferred viewpoints are around on-axis views, where the principal axis of elongation is either perpendicular or parallel to the line of sight and flat surfaces are presented approximately perpendicular to the line of sight – so called planar views. Here we present a morphological shape analysis of the object views selected by a crosssectional sample of children that manipulated objects in the Pereira et al. (2010) study (N = 54, 12-36 months). We followed an image-based (pixel-based) approach; we coded 3D object orientation and created computer-generated images of the object; finally, we extracted two shape measures from the generated images. In particular we computed surface area and aspect ratio. For the main analysis we investigated if the shape measures differ between planar and non-planar views. In addition, and for a smaller subset of 30-36 month olds (N = 8) we computed the number of pixels that do not overlap between consecutive frames (a measure of image variability). There were two key results: (1) on average, planar views have lower surface area (only in the oldest age groups), and aspect ratio increased with developmental age; and (2) on average, consecutive frames of planar views have a lower proportion of pixels that do not overlap, compared with non planar views. We discuss these results in the context of their contribution to our understanding of the development of visual object perception.