Children's understandings of the attributes of life

Previous investigations of children's understandings of the life concept have focused on their classifications of the life status of familiar objects. In this study, we attempted to examine more directly the processes by which children infer life status by examining their reasoning about unfamiliar objects. In Experiment 1, 4- to 11-year-olds and adults were asked to name attributes of living things to establish which attributes they associated most closely with life. Children age 7 and younger most often named attributes true only of animals but not of plants; older children more often named attributes true of both animals and plants. However, movement was the single attribute cited most frequently by children of all ages tested. In Experiment 2, 4- to 11-year-olds and adults were presented information about attributes of imaginary objects on a distant planet and were asked to infer if those objects were alive. Again, young children relied relatively heavily on qualities true only of animals but not of plants, whereas older children relied more on attributes true of both plants and animals. Also as before, movement was viewed as indicative of life at all ages tested. In Experiment 3, we examined the hypothesis that children discriminate among different types of motion and that the types of motion they associate with life are in fact typical of living things. Children ranging from age 5 through 11 were found to discriminate among different types of motion and to infer that objects were alive only when they showed the types of motion typical of living beings. The results of Experiment 3 allowed interpretation of seemingly conflicting results that have arisen in previous studies, as well as in Experiments 1 and 2 of the present study.