The literary device that uses exaggeration for effect is called hyperbole. Hyperbole is a figure of speech in which statements are exaggerated or overstated to create a dramatic, humorous, or emotional effect. It is often employed in poetry, literature, and everyday language to emphasize certain qualities or characteristics. For instance, saying "I’m so hungry I could eat a horse" is a hyperbolic expression used to illustrate extreme hunger. While hyperbole shouldn't be taken literally, it serves to engage readers and listeners, making the message more impactful through its exaggerated nature.