| The present dissertation tested the hypothesis that software pedagogical agents can promote constructivist learning in a discovery-based multimedia environment. In a preliminary study, students who received a computer-based lesson on environmental science performed better on subsequent tests of problem solving and motivation when they learned with the mediation of a fictional agent compared to when they learned the same material from text. In order to investigate further the basis for this personal agent effect, I varied whether the agent's words were presented as speech or on-screen text and whether or not the agent's image appeared on the screen. Both with a fictional agent (Experiment 1) and a video of a human face (Experiment 2), students performed better on tests of retention, problem-solving transfer, and program ratings when words were presented as speech rather than on-screen text (producing a modality effect) but visual presence of the agent did not affect test performance (producing no image effect). Next, I varied whether or not the agent's words were presented in conversational style (i.e., as dialogue) or formal style (i.e., as monologue) both using speech (Experiment 3) and on-screen text (Experiment 4). In both experiments, there was a dialogue effect in which conversational-style produced better retention and transfer performance. Students who learned with conversational-style text rated the program more favorably than those who learned with monologue-style text. The results support cognitive principles of multimedia learning which underlie the understanding of a computer lesson about a complex scientific system. |
