What are some bad effects of bullets in presentations?

Question

I get confused with some comments of JeffE on this question. Those are:

...avoid bullets entirely.

Powerpoint doesn't kill people. Bullets kill people.

The comments got a lot of upvotes, so there are many people agree with them. And I don't understand why.

I use block and itemize extensively, and I think they provide a clear structure to my presentation. The bullets are the key points that I want to present on that slide.

So why people think they are so bad?

I have to emphasize that the question above asked about teaching, while I only give presentations. Are there any differences?

---

UPDATE

Thank you for the excellent answers (I still want to hear from JeffE). I can kind of understand that using only bullets is not enough, but avoiding them entirely is a personal opinion, not a general rule.

By the way, the best presentation I've seen so far is the last lecture of Randy Pausch, in which he used a fair amount of bullets.

Answer 1

TL;DR: A bulleted list onlys show one kind of relationship (either sequence or membership in a set). If you want to show another kind of relationship, it's better to use something else. If you want to show sequence/membership AND something else, you can either use a different visual tool (not a list) or a list + additional dimensions.

---

Bullets are useful to help speakers remember what they wanted to talk about, but they're not a powerful way to visually convey ideas and relationships between ideas.

To quote Edward Tufte in The Cognitive Style of Powerpoint:

By leaving out the narrative between the points, the bullet outline ignores and conceals the causal assumptions and analytic structure of the reasoning.

He in turn quotes the Harvard Business Review:

Bullets leave critical relationships unspecified. Lists can communicate only three logical relationships: sequence (first to last in time); priority (least to most important or vice versa); or simple membership in a set (these items relate to one another in some way, but the nature of that relationship remains unstated). And a list can show only one of those relationships at a time.

Bullets may be OK when you want to convey sequence or membership in a set. But even then, lists often have more than one dimension, in which case there are almost certainly better ways to present this than just as a plain text list with bullets. For example, take this slide showing an outline of a talk by Tom Rondeau:

and compare it to the classic way to show an outline with a list:

The point of this example is to show that the "plain" list, which is a fairly standard way to show an outline, conveys one dimension. The list version conveys sequence, which bullets can do fairly well (the parenthesis attempt to add another dimension, but it's subtle). The graphical version shows the sequence of the talk and also adds a color dimension to show the content of each section and its classification.

You could of course add extra dimensions to the list, too. This image was contributed by Eddie:

But if you are just listing points and not trying to show order, priority, or membership, all the more reason to stay away from lists.

Also see Bullets versus sentences in posters (I hate bullets in posters).

Answer 2

Susan Weinschenk says it best:

You know what I call slides with a lot of text? Your notes.

If you give people a slide with a lot of text, people will start reading the text. When they read, they can't listen. The attention should be on the words you're saying, not the ones on the slides. In most cases, a blank slide is better than one with too much text.

Of course, bullets don't necessarily mean blocks of text, and if you have three bullet points with three words each, the bullet list may not be such a bad option. But a sentence per bullet is pushing it already. If you make your presentation by opening powerpoint and typing the things you're going to say into a list of bullets, you're writing your notes, and the audience don't need to see those.

Bullets are also the first type of slide that comes to mind, and the first option powerpoint shows you. They are a crutch that stops you from coming up with a better slide. Try drawing the slide you need for your story on paper, and then figuring out how to get get it drawn on the computer.

Answer 3

I think it is important to balance bullet points (or other text) and visuals. While it is awful to have screens full of text, the key points should additionally be made with text on the slides.

(1) Massively helps people who can't hear you, who are working in a language that is difficult for them, or can't understand your accent. It is very important that there is text for them to read so they can follow the messages of the presentation. In academia, you should always assume there are some people in the audience who can't comprehend as quickly as you speak.

(2) Makes your slides useful later. If the key points are written on your slides, then you can hand out a copy of your slides. I don't write an additional paper when I present, the abstract and slides are sufficient. A presentation that is all images is much better to participate in, but hopeless for later remembering what the brilliant presentation was actually about.

Answer 4

Adding to the others, one more excellent resource: Patrick Winston's "How to Speak" lecture, which recursively self-demonstrates every heuristic point it makes.

The version I've linked to is from before the dominance of PowerPoint and is primarily a chalk-talk, but it has a section on overhead transparencies that hits the same key points. This talk provides a lot of good heuristics on communication that includes why you want to not use dense bullet points. Among other key ideas:

• Mixing images and words gives two cognitive channels of communication, which greatly improves understanding.
• You need to slow yourself down, so that people have time enough to digest what you're saying.
• Having lots of words means people will be reading the slides rather than listening to you