How do toddlers learn the names of geometric forms? Past work suggests that preschoolers have fragmentary knowledge and that defining properties are not understood until well into elementary school. The current study investigates when children first begin to understand shape names and how they apply those labels to unusual instances. We tested 25- and 30-month-old children's (N = 30 each) understanding of names for canonical shapes (commonly-encountered instances, e.g., equilateral triangles), non-canonical shapes (more irregular instances, e.g., scalene triangles), and embedded shapes (shapes within a larger picture, e.g., triangular slices of pizza). At 25 months, children know very few names, including those for canonical shapes. By 30 months, however, children have acquired more shape names, and are beginning to apply them to some of the less typical instances of the shapes. Possible mechanisms driving this initial development of shape knowledge and implications of that development for school readiness are explored.
Keywords: executive function; mathematics/number concepts; spatial cognition; spatial reasoning.