The purpose of this paper was to explore the concept of interest, one of the critical positive emotions in learning contexts and to investigate the effects of different types of visual illustrations on learning interest, achievement, and motivation in multimedia learning. The concept of interest was explored in light of positive emotion; an experiment was conducted to examine the effects of visual illustrations. In the experiment, participants were drawn from two classes of "Introduction to Educational Technology" and randomly assigned to one of the three conditions: a) cognitive interest illustration condition, b) emotional interest illustration condition, and c) text-only condition. The cognitive interest illustrations were designed to promote learners cognitive interest by showing the scientific principle with corresponding illustrations. The emotional interest illustrations were designed to increase learners' emotional interest by providing interesting but peripherally relevant illustrations. The text-only condition presented text information only with no illustrations. Results revealed that the post interest was different between the cognitive interest group and the text-only group, and also between the emotional interest group and the text-only group. The study also revealed a significant difference in learners' motivation. The types of visual illustration, however, did not have an effect on learners' information recall or on comprehension.