Developmental differences in scientific discovery processes

The purpose of the three studies reported here was to formulate a framework for understanding the development of scientific reasoning processes. Subjects were placed in a simulated scientific discovery context by first teaching them how to use an electronic device and then asking them to discover how a hitherto unencountered function worked. To do this task, subjects had to formulate hypotheses based on their prior knowledge, conduct experiments, and evaluate the results of their experiments. In the first study, using 20 adult subjects, we identified two main strategies for generating new hypotheses. One strategy was to search memory and the other was to generalize from the results of previous experiments. In a second study, with 10 adults, we investigated how subjects search the space of hypotheses by instructing them to state all the hypotheses that they could think of prior to conducting any experiments. Following this phase, subjects were then allowed to conduct experiments. Subjects who could not think of the correct rule in the hypothesis generation phase discovered the correct rule only by generalizing from the results of experiments in the experimental phase. In a third study, twenty-two 3rd to 6th grade children were given the same task as the adults in study 1. Only two of them discovered the correct rule, but 14 of them asserted that they were certain that they had discovered it. At the level of subjects' global behavior on this task, there was little difference between the children and the adults. Both groups understood the nature of the task and realized that they could discover how the device works by making it behave, observing that behavior, and generating a generalization about it. However, viewed at the level of overall success rates, there were profound differences in the consequences of how this general orientation toward discovery was implemented. The adults had a 95% success rate, while 90% of the children failed. There were three main sources of this performance difference. First, children proposed different hypotheses than the adults did. Second, the children did not abandon their current frame and search the Hypothesis space for a new frame, or use the results of experiment space search to induce a new frame. Third, the children did not attempt to check whether their hypotheses were consistent with prior data. * * These studies provided support for the view that scientific reasoning is a search in two problem spaces. By extending Simon and Lea's (1974) Generalized Rule Inducer, we present a general model of Scientific Discovery as Dual Search (SDDS) that shows how search in two problem spaces (an hypothesis space and an experiment space) shapes hypothesis generation, experimental design, and the evaluation of hypotheses. The model also shows how these processes interact with each other and suggests what their developmental course might be. Scientific Discovery Table of