Visual (sight) because of the descriptive comparison of the outlines, you can almost see what they look like. It is like the author hands you a photo of the words in action.
Sensory imagery in literature refers to the use of language or expressions carefully selected to appeal to one or more senses in the reader. In the case of the excerpt "the sprawling outlines run off in great slanting waves of optic horror, like a lot of wallowing seaweeds in full chase" that The Yellow Wallpaper by Charlotte Perkins Gillman, the author appeals to the sight of the reader because she describes the strange lines in the wallpaper by using precise language such as "sprawling outlines" or "like a lot of wallowing seaweeds" that allow the reader to create a mental image of the wallpaper. Also, the word "optic" in "slanting waves of optic horror" shows the author is focusing on the visual aspect of the wallpaper. Thus, the type of sensory imagery is visual as it appeals to sight.
