26 October 2013

How to prepare a presentation - style tips

In a previous post I discussed technical tips for presentations. Here I will say a few words about the style and I will conclude with a third post about the content.

At some level, every point below derives from one general principle: style is subordinated to effectiveness. Each one of your choices should make for easier communication with the audience.

Space and content

Do not fill up your slides with information. I aim for one image (two of them, at most) or a maximum of ten lines of text per slide (five would probably be better). Leave ample space at the margins and between page elements (images, equations, text areas). The Steve Jobs style (one word per slide) is probably not a good idea for science presentations, but ideally the content should not cover more than half of the available area (for text slides, at least.) More about this in the next post.

Colors

  • Use a high contrast color scheme. I use black text (with some red for emphasis) on white background. Some find this too harsh and prefer an off-white background or lighter text color.
  • White text on dark background is also a popular choice. I suppose that, in a dark room, the lower light level makes the eye more sensitive to intensity variations (as per Weber's law) and thus eases picking up details in images. This may be why the scheme is popular with biologists.
  • Avoid light colors (especially yellow) on white background. Nobody uses them for text, of course, but I have often seen (or rather not seen) yellow curves in graphs.

Fonts

I think that choosing a typeface is a matter of personal preference more than anything else. My suggestions would be:
  • For a distinctive look avoid very common typefaces (Arial, Helvetica, Times, Comic Sans MS, Computer Modern Roman, etc.) Go for subtle differences, though: you want people to remember the contents of your talk, not the wacky lettering.
  • Use only one font family throughout (with a possible exception for slide titles). In particular, the math fonts should be visually compatible with the text. The default LaTeX typeface (Computer Modern Roman) fits the bill, but when changing the text font be sure to replace the math font accordingly. I use the pxfonts package, which sets normal text in Palatino (URW Palladio L, in fact) and maths in the italics of the same typeface.
  • Choose a font with wide enough horizontal spacing. I also prefer a larger width-to-height ratio for presentations than for dense blocks of text (as in books). For instance, I am OK with Times New Roman for a full page of text but would not use it in my slides. See the figure below for a comparison between different typefaces (regular font), at the same size: 

     I also encountered a number of prescriptions that I do not necessarily agree with. Here are some more frequent ones:
    • Use sans serif fonts in presentations and serif in denser text, since the former is supposed to be more legible.In the list above, I do not think Arial is more legible than Palatino.
    • Never, ever use Comic Sans.The reasons presented are manifold:
      • It is ugly. I tend to agree, but I also find it very legible, and thus suitable for presentations. After all, monotype fonts are also ugly, but we still use them for programming
      • It is too widely employed. This is also true, and the main reason I'm not recommending it, but its critics seldom stop to consider why it is so widely used. Could it be simply that it is adapted to its purpose ?!
      • It is not "serious" enough, having been inspired by comic book lettering. By now, Comic is so familiar to us all that I think any such associations no longer carry any weight. We recognize it as "that ugly font everybody uses" and that's it. And, once again, maybe comic book captions are designed to be legible ?
    Font suggestions: Century, Bookman Old Style, Palatino, (serif), Lucida Sans, Open Sans (the bold face), Trebuchet, Verdana (sans serif).

    Animations

    They can be very useful for conveying information, such as the time evolution of a system, but should be used sparingly (in particular, do not reveal list items one at a time). I would also avoid fancy transition effects.

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