The illusion of understanding hypothesis asserts that, when people are learning with multimedia presentations, the addition of animation can affect metacognitive monitoring such that they perceive the presentation to be easier to understand and develop more optimistic metacomprehension. As a result, learners invest less cognitive effort when learning with animation. This study tested the illusion of understanding hypothesis with a randomized, double-blind, 2 x 2 factorial design using two different types of animation--representational and directive. Representational animation had a negative effect on learning, and directive animation had a positive effect. Both representational and directive animations induced illusion of understanding. Moreover, the animations induced multiple forms of the illusion. Consistent with expertise reversal effect, the animations induced more optimistic metacomprehension in low-proficiency learners but more pessimistic metacomprehension in high-proficiency learners. (Contains 1 figure and 4 tables.)