Beyond labeling: the role of maternal input in the acquisition of richly structured categories

Recent research shows that preschool children are skilled classifiers, using categories both to organize information efficiently and to extend knowledge beyond what is already known. Moreover, by 2 1/2 years of age, children are sensitive to nonobvious properties of categories and assume that category members share underlying similarities. Why do children expect categories to have this rich structure, and how do children appropriately limit this expectation to certain domains (i.e., animals vs. artifacts)? The present studies explore the role of maternal input, providing one of the first detailed looks at how mothers convey information about category structure during naturalistic interactions. Forty-six mothers and their 20- or 35-month-old children read picture books together. Sessions were videotaped, and the resulting transcripts were coded for explicit and implicit discussion of animal and artifact categories. Sequences of gestures toward pictures were also examined in order to reveal the focus of attention and implicit links. drawn between items. Results indicate that mothers provided a rich array of information beyond simple labeling routines. Taxonomic categories were stressed in subtle and indirect ways, in both speech and gesture, especially for animals. Statements and gestures that linked two pictures were more frequent for taxonomically related animal pictures than for other picture pairs. Mothers also generalized category information using generic noun phrases, again more for animals than for artifacts. However, mothers provided little explicit discussion of nonobvious similarities, underlying properties, or inductive potential among category members. These data suggest possible mechanisms by which a notion of kind is conveyed in the absence of detailed information about category essences.