In the previous message we spoke about visual language and the importance of knowing its rules in order to visualise properly. In this one we focus on visual rhetoric, since although knowing the grammar you can speak a language correctly, in order for the message to be well understood you have, moreover, to know how to argue properly. 

According to my preferred dictionaries* rhetoric is “the study of the technique of using the language properly”. A second meaning relates it with “the art of using speech to persuade, influence or delight”. Art and science… old fellows of the designer.

Classical rhetoric appeared in ancient times, apparently in Sicily around 500 B.C ., when, in order to overcome popular judgements you were required to defend yourself and, hence, dominating the art of convincing. It evolved with the work, among others, of Aristotle (300. BC) Cicero and Quintillianus (100. AD) who wrote the influential treaty in twelve volumes Institutio Oratoria. Currently the different parts that make it up are part of linguistics.

The objective of rhetoric was (and still is) to persuade through language. Although the objective of Information Visualisation is not to persuade but to enhance insight, there are certain rhetoric aspects of visual language that are worth considering.

Claire Dormann, from the Vrije Universiteit in Amsterdam has been studying the topic for many years. According to Dormann there are three types of arguments you can use to persuade:

• Ethical. “Because this is correct”.
  
  
• Emotional. “Because it’s what your heart demands”
  
  
• Rational. “Because it’s reasonable”

In order to build those arguments rhetoric figures are used. They are intentional and structured deviations from the usual way of expression, visual expression in this case.

Personification. Willie Wiredhand, the  mascot of the american rural electric movement. Source: Southwestern Electric Corporation	Visual pun.  "Vertumnus" (1590-1591) by Giuseppe Arcimboldo. Arcimboldo's visual puns are famous by the composition of human characters by accumulating different kinds of vegetables in an astounding visual effect. Source: abcgallery.com	Metonymy. In this ad of Absolut Vodka the beverage is substituted by its continent (the bottle). Here metonymy is double due to the association of the city of Geneva with the typical Swiss watch, from which the bottle is a piece.  Souce:  AbsolutAd.org

In her web site Digital Persuasion   you can see the main figures of visual rhetoric. Among them you find: 

• Accent: The object of our interest is shown, for example, in full colour while the rest appears in black and white. Common in advertising.
  
  
• Anacoluthon. The exchange of elements in a sentence that breaks the syntactic rules. Visually it implies an impossible image. For instance, in a detergent ad, the TV character that comes out from the screen to clean the house of the TV viewer. 
  
  
• Hyperbole. The exaggeration to make the prominence of an object or argument more evident.
  

Metaphor. In this ad the left picture appears cracked. To the right a zoom of it without cracking makes reference to the elimination of the wrinkles thanks to the product. Source: Retórica e Publicidade.	Hyperbole. Exaggeration is widely used in publicity. Here the exaggeration is about the strength of the boot of the Caterpillar brand. Source Retórica e Publicidade.

• Metaphor. Based on the analogy between what is shown and what is intended to be meant. The metaphor is one of the most powerful figures in the visual field and it’s used extensively. The desktop, windows, buttons…
  
  
• Metonymy. Substitution of terms based on the mental association between what is shown and its meaning due to a causal, spatial or temporal relationship. For example, substituting the work for the author, the product for the place where it’s produced or the object for its use.
  
  
• Synecdoque A particular case of metonymy where the whole is substituted for a part. Archetypical examples are Big Ben in substitution of London or the Eiffel Tower for Paris. Typical in travel guides.
  
  
• Personification. Giving human features to inanimate objects. 
  
  
• Visual pun. The visual equivalent to a pun. For example a zipper where the teeth are the letters of a sentence describing the zipper.

And some more figures that, along with graphic examples are worth seeing in the above mentioned web site. Those interested in bibliography could visit the web site of Syracuse University on visual rhetoric by Rebecca Moore Howard or the course given at Purdue. On the other hand Parlor Press is preparing a series of publications on visual rhetoric (I owe the link to James Wise)

And in Portuguese we find the excellent page "Retórica e Publicidade" that compiles very interesting examples of a wide range of rhetoric figures coming from advertisements. Indispensable for being considerably complete and with many graphic examples.

Where do we want to go with all this? Should we wish to excel in using visual language, we have to take into account that there’s also a visual “oratory”.

In the same way as rhetoric can produce a hollow message (just take a look at TV for a while) we can send attractive visual messages without any valuable information. Our responsibility is to use or not the visual language along with all its techniques with the goal of making what is complex understandable.

* Diccionario Enciclopédico Salvat Universal. The Collins English Dictionary.

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