The development of reasoning about causal and noncausal influences on levers

2 studies examined 5-12-year-olds' judgments regarding the behavior of balance scales and other levers whose arms varied in a causal (the number of equally weighted objects or their distances from the fulcrum) or a noncausal (the color, position, or orientation of objects) variable. There were age-related increases in correct judgments for each causal and noncausal variable, with children tending to make correct judgments about the influence of physical features of objects (their number and color) at an earlier age than they did about spatial relations between objects (their distance, orientation, and position). Children's patterns of errors judging the influence of causal (particularly distance) and noncausal (particularly position and orientation) variables were different, and there was no relation between children's correct judgments regarding causal and noncausal variables. The results suggest that there are separate processes underlying children's ability to identify causal and dismiss noncausal influences on levers which are dependent on the kinds of features (physical or both physical and spatial) which children conceive of as potentially influencing the behavior of levers.