Metaphor works by mapping narrative inference structure from one domain of knowledge or experience to another. This kind of cross-domain mapping can of course be accomplished through words, but because metaphor is primarily a function of thought rather than language, we should expect to find the dynamics of metaphor not only in the things we say, but also in how we evaluate situations, make decisions, imagine the future, etc.
Metaphors can therefore also be developed by images, not just by words. My favorite book on this subject is Charles Forceville’s Pictorial Metaphor in Advertising. We find metaphor (not merely blending) when we are asked to reason about one thing in terms of something else. Consider the image below:
Here there are two distinct domains evoked by the image: the cigarets are being presented in terms of a shotgun. Notice that there is already a decision about directionality being made: a PhD student serving in Hong Kong recently assumed that GUNS were being presented in terms of CIGARETS, which would make this a different metaphor. The context (or development) of the lung cancer awareness logo at the bottom right helped him revise his understanding of the metaphor, but changing the direction of the mapping changes the metaphor: metaphor is not a two way street.
The inferences we are invited to make–that indeed we do make, perhaps at a subconscious or emotional level–center around what we know about guns and their potential to do harm. Just as it would be foolish to put a shotgun in your mouth (unless you were trying to kill yourself), so we are to evaluate smoking in a similar way: putting cigarets in your mouth is down right foolish, unless you are trying to kill yourself.
The powerful revulsion you may feel viewing this ad comes from the strong inference that shotguns are dangerous and they don’t belong anywhere near your mouth. Further inferences could also be drawn–like smoking is potentially deadly to those in close proximity to the smoker–but we don’t need an exhaustive list of what this pictorial metaphor conveys. Instead, we can image the ad intends the kinds of inferences that come from thinking of cigarets as a kind of shotgun. The specifics may vary from individual to individual, but some central themes will emerge again and again.
One of the most effective ways to change behavior is to give people a new metaphor through which to view their actions. Here, the cues given by the image evoke both the shotgun and cigaret domains. But other advertisers (and authors or preachers) will evoke inference patterns in one domain for the purpose of shaping the inferences and therefore lives of their audiences. Metaphor is a powerful–and dangerous!–tool to wield.