The focus of this study is on visual metaphors, which are pictorial counterparts of verbal metaphors such as "The sky is crying," or "The man is a wolf. In this study, our aim is to examine different kinds of visual metaphors: How are they generated and how are they different from verbal metaphors. We explore the difference between them at the cognitive level. We empirically show that processing of visual and verbal metaphor differs at the perceptual level, and this difference effects the overall metaphor comprehension. We argue that since visual metaphors are represented in visual modality, theories of verbal metaphor may not be able to explain processing of visual metaphor adequately. Therefore, we must look for a comprehensive theory of visual metaphor. This theory must consider the role of perceptual processes and other cognitive processes such as imagery and memory, in visual metaphor comprehension process. The results of our study can be seen as a starting point for the development of such a theory.