Researchers have identified 2 distinctive types of pictorial displays, namely, pictorial metaphor and pictorial simile, and offered theoretical explanations of them. Regarding the distinction between pictorial metaphor and pictorial simile, we argue that symmetric image alignment of pictorial components depicting things at the object level is the principal design factor that sets pictorial simile apart from pictorial metaphor and links pictorial simile to pictorial grouping. Based on the idea of symmetric image alignment, an attempt is made to identify and explain (...) a further type of pictorial display, namely, pictorial oxymoron. We propose a hypothesis, called the "image grouping hypothesis," to provide an integrated account of pictorial grouping, pictorial simile, and pictorial oxymoron. The hypothesis can be summed up as follows: Symmetric image alignment of pictorial components depicting things of the same kind is apt for expressing pictorial grouping; symmetric image alignment of pictorial components depicting things of different kinds is apt for expressing pictorial simile; and symmetric image alignment of pictorial components depicting things that can be seen as incompatible with each other is apt for expressing pictorial oxymoron. (shrink)