Children's and adults' knowledge of species-general and species-specific changes during physical growth and development

Abstract

CHILDREN'S AND ADULTS’ KNOWLEDGE OF SPECIES-GENERAL AND SPECIES-SPECIFIC CHANGES DURING PHYSICAL GROWTH AND DEVELOPMENT

GAYATHRI NARASIMHAM

Dissertation under the direction of Professor John J. Rieser An integral part of biological knowledge is understanding that although all species increase in stature during physical growth, some undergo changes in body-head proportion (for example, mammals) and others do not (for example, reptiles). Three experiments examined the degree to which preschoolers, third graders, and adults differentiate principles of growth of different species, knowledge implicit in their perceptual classifications of line drawings of animals, and explicit in their verbal explanations. Results showed that while preschoolers based their implicit judgments about mammalian growth on proportional changes, they do not use the proportion rule when size conflicts with proportional changes. Interestingly, third-graders and adults judged by proportion even when size was in conflict, but only with mammal species. Preschoolers and school children judged predominantly by size in the case of reptiles and novel species. Adults judged by size, but also used the proportion rule with reptile and novel species. Explicit verbalizations revealed that preschoolers talked about size changes as the main factor in judging age, whereas school-age children and adults talked about more discerning features, and only adults talked about proportional differences.