Part 2 of a three part blog post. First part was on color merges. Perhaps there will be a third on 3d plots, which is the least pressing because it is the least common and the least damaging.
Laser pointers are the most common, and they invariably make for a poorer presentation than without it. Here are the three fundamental problems with the use of laser pointers in talks.
- Laser pointers do not point at things, they point on things. In fact, the term "laser pointer" is a misnomer. It is just a laser point. It does not produce a pointer, such as an arrow or a pointing hand. To highlight a feature with the laser you must overlap it with your extremely bright laser point, completely obscuring the feature as well as readjusting your eye's dynamic range to make the actual features on the slide harder to see. Laser pointer companies pride themselves in outdoing each other with brightness, and audiences are impressed by green laser pointers, the most distracting of all. This is missing the ... "point". When attempting to highlight punctate features the problem finds its ultimate aggravation (and don't get me started when laser pointing on color-merged puncta. Save our souls!). When a laser pointer is activated, its dot is invariably the brightest thing for your eye to look at. In summary, if you use a laser pointer, we in the audience see the laser dot. Not the thing you want us to see.
- The laser pointer is the only moving thing in our field of view. Suppose you were looking at a completely stationary picture and something moves in it. We are going to pay attention to the part that moves, not the part that sits still. Otherwise we have to use extreme concentration to suppress our instinct to focus on the stationary medium-intensity background instead of the in-motion brightly colored laser spot. In doing so, we are attempting to suppress an evolved instinct that saved our ancestors' necks countless times. This is another reason why when a presenter uses a laser pointer, we focus on the laser point, not whatever it is he/she is trying to point at.
- A laser pointer fosters the detachment of the presenter from the presentation. This is unfortunately the standard presentation mode by the entire community without anyone ever having made a conscious choice about it and has broader sources than just laser pointers. The modern scientific talk has turned into a kind of slide-cast where we all look at the slides and listen to the disembodied voice of the presenter. The two are sporadically connected by a device that projects an unseen beam ending in a bright dot. When a presenter wants to point at a feature, he/she will often step back from the presentation, further increasing the detachment. Is that how you want to learn? From a slide or from a person? Would you be happy if that's how your kids got taught in school? Do you want a talk where the slides are an aid and extension of the presenter, or one in which the presenter's role is to provide commentary on slides? I decided many years ago that scientists are more interesting that powerpoints, so if a presenter forces me to pick between looking at the slides and looking at them (which most do), I always look at them and mostly ignore whatever is projected.
So what are good pointing devices to use?
- Your hand. Best pointing device invented. Unlike the laser pointer, you can point at stuff with this, not just on stuff. Walk into your slide if necessary. It is your helper, not the other way around. Stay connected to it.
- A stick. Another classic pointing device. It extends your hand nicely to get to some of those plots you put at the top of your slide.
- Arrows in the presentation. If you can't do the first two, which may be if you have to talk in an enormous lecture hall and your podium has been unwisely (but commonly) placed far from the projection screens, you can animate an arrow to appear on your slide when you want to call attention to something. This requires you to think beforehand about what you want to call attention to.
What is a good use of a laser pointer?
Turns out they make passable lasers for optical applications. You can use them to align your complicated optical experiment, or even do fluorescence microscopy (I've used them for both). It is also apparently the case that the laser dot is very entertaining to cats and they chase after it like it is prey, which coming to think of it is a lot like what we humans do (points 1 and 2 above), so they sell these pointers at pet stores. Unlike humans, though, my brother reports that his cat eventually tired of the novelty.