Thus far you have been approaching your presentation from a textual perspective. Now we welcome a true rhetoric superpower aboard: images.

The visual channel always wins

A presentation with slides is a so-called multimedia message. It consists of sounds and images. Thus, it sends simultaneously information through the panel member’s auditory and their visual channel. The big advantage is that images and sounds reinforce one another by exploiting more ‘band-width’. Well-designed multimedia messages lead to better understanding and retention than messages that utilize just one channel. That is, as long as both channels send the same message. If not, the visual channel always wins. Which is the case when there is a discrepancy between the two, or if the image captivates all the attention because of their complexity or the emotional response they evoke.

The dominance of the visual channel has a long history. We could decode visual information long before we could understand spoken language. Both as a species and as individuals. Processing visual information is a typical fast-mind, automatic, and effortless process. On the other hand, decoding language is a slow-mind process which requires attention and takes time. Reading written text is extra demanding. It needs to be translated into sounds first.

Therefore you can say that words speak to our heads (or neo-cortex), images speak to our hearts (or our lizard brain). In a context in which convincing is the ultimate goal, you can use this to your advantage. You can use images to let the panel understand instantaneously what is difficult to explain in words. And, you can use images to make them feel the urgency of your research. In other words: you can use images rhetorically.

Textframe: Functions of images

We promote a functional use of images. Know why you use a particular picture. Good reasons to use images are:

• The image shows places, organisms and objects which normally fall outside our perception (e.g. because they are too small, too large or too far away for the human eye to perceive).
• The image provides an overview of large quantities of data (e.g. graphs or tables).
• The image clarifies complex concepts (e.g. infographics and schemes).
• The image clarifies complex relations (e.g. schematic overviews and organograms).
• The image does justice to complexity. Some processes or structures can be difficult to explain in words.
• The image contains a message that cannot be misunderstood.
• The image makes it easier to draw a comparison.
• The image tells a story, provides evidence and convinces.
• The image excites, moves and entertains.

Bad reasons to use an image are:

• Because you have it
• Otherwise the slide looks so empty (decoration)

Textframe: Visual rhetoric

Images are ideal tools to use for rhetorical purposes. Examples of rhetoric use of images are:

• Ethos. Images can contribute to your credibility. Well-designed slides make you look more credible, as do such elements as your choice of clothing and your body language. Snippets of your previous papers, demonstrate your qualities as a researcher.
• Pathos. Images can evoke strong emotions. This is a very powerful tool which is rarely used in scientific presentations. Images touch much more directly on emotions than words. You can use images to provoke your audience’s emotions and emphasise the urgency and importance of your research. A photograph of a seahorse holding on to a cotton swab makes you feel the problem of plastic pollution much more than a bar chart.
• Logos. Images also can function as rational arguments. Graphs, models and tables are all visual uses of logos. Likewise, the image of a drug lord in handcuffs is a proof of his arrest. As often is the case, this latter example also serves the purpose of entertainment and selling newspapers.