I think the pictures are perfect. Pictures entertain the more creative side of the brain so that it doesn't start distracting the more logical side from paying attention. All of your pictures tie in well with your topic. By reusing images the creative side of the brain will have something to do, by flooding the watcher with memories of what was going on last time they saw that image. Finally, for those who have given up on paying attention to your material (perhaps it's not relevant, perhaps they just came because a friend was coming, perhaps their stomach hurts), pictures give them a reason to keep looking up.

I help pjf with his talks all the time. We've found through experience, that fast moving slides with lots of pictures, get a much better reaction than a few pictures here and there.

If asked, I'd say that one picture every 4-5 slides is not a bad goal to aim for, but it should be a *minimum*. It depends a lot on how fast your slides move. I'd suggest you want one picture every 90 seconds. If you spend 2 minutes per slide, that's one picture per slide. If you spend 6 - 10 seconds per slide (as we tend to do these days) then that's on picture every 9 - 15 slides. After enough talks you get a feel for it though.

Anyway, I'm sorry I didn't comment sooner, but thanks for putting these up; I found it very interesting and am sad I wasn't as OSCON to attend!

jarich

I wish you were at OSCON as well. I would have loved to have met you, and you should have received your award in person. Perhaps you'll be at the next OSCON?

In the talk I was spending about a minute and a half per slide, and I didn't feel unhappy during the presentation with the pictures. The feedback that I've gotten so far on the talk has been positive. However it was so much work to put together that I'm going to be in no hurry to repeat the experience. :-/

Btw. I asked one of the best lecturers here at the university whether my advice about the pictures was correct and he said: A picture every 4 or 5 slides is enough and the pictures must be directly connected to the slide otherwise the listeners minds will wander off.

But if you loathe to throw those pictures out now (or you think my advice makes no sense), leave them in. This is then version A of your lecturer-test. Afterwards you can ask some of the listeners if they had trouble concentrating. Next time you give this presentation, show version B with fewer and more relevant pictures. Naturally that is comparing apples to oranges. You have a different audience and there are other factors like time of day and how good you present and the sample is pretty small. But on the third lecture you have an example A/B test you can talk about ;-)

I actually always had that. I just made it several slides.

I also disagree on which solution is best. I've seen multiple programmers try to implement that function and mess it up. There are a number of subtle requirements you have to get right, and I don't think there is any clearer presentation of how to get them right than to show code. I'm not concerned about the common case being wrong. I'm concerned about the production hook going missing, programmers doing the random assignment as $person_id % 2, and other similar mistakes.

I'm leaving the pictures in. I've asked a number of people for feedback, and the consensus of most of them is that the current pictures work well. While I agree that they can be a distraction for someone who is getting lost, I have points where people can resynchronize. And the talk has multiple audiences within any organization, I expect people to lose interest when I'm presenting about stuff they are not interested in. I'd like them to remain somewhat entertained, and then I'd like to get their attention when we move on to a section they care about.

If the presentation should have the double function of providing a manual later on, then you are correct. So you sacrifice a little clarity at the presentation for better value later. For the presentation alone a picture/diagram would still be better

About the pictures: Good point about the resynchronization. But I think the distraction is no danger for people already lost. It is a danger for tired listeners, for listeners where the coffee is wearing off, for everyone after the one hour mark into the presentation. On the other hand your point about keeping the ones with lost interest entertained is in these circumstances very seductive. Can't argue against that.