Volunteer theory 3

29 02 2016

Here are three examples where presenters are speaking about exponential growth. 

Richard Dawkins (speaking about population growth) and Chris Bishop (speaking about computer processing speed increases) use volunteers to carry out their demonstrations. David Suzuki (speaking about human impact on the atmosphere) chooses not to.

I find Suzuki’s explanation of exponential growth clearer than either Bishop’s or Dawkins’ and this is in part due to his choosing not to employ volunteers. 

As I explained in this post there is a cost to employing volunteers. It takes up valuable time, it relinquishes control and it can be a distraction. If volunteers are used effectively then those costs can be outweighed by the benefits but that means the volunteers must actually be useful, promote positive emotions and add drama. If their use accomplishes none of these objectives then it is better not to use them. 

If a volunteer isn’t performing at least one of these six reasons to use a volunteer (extra pair of hands, naive actor, promote empathy, to react, to increase jeopardy and/or provide a different voice) then they have no place up on stage with you but more importantly it is OK for you not to use them. 

My advice to both Bishop and Dawkins would be to just carry out the demos themselves. The benefits of using their volunteers is outweighed by the costs. Worse, the clarity of their descriptions of exponential growth suffer because of the volunteers. 

Richard Dawkins [watch from 6:30 mins] gets two volunteers to fold a large piece of paper.

He wants to show us the effects of doubling a bacteria population 50 times. His volunteers aren’t acting as an extra pair of hands, he could easily have done this himself; they are not acting a naive actors, there is no possibility for trickery and they are not asked to confirm anything; we don’t empathise positively with them, if anything I felt awkward and embarrassed with and for them as they were allowed to “fail”; they don’t react, we don’t see them struggle as their backs are to us; their use doesn’t increase jeopardy and they are not invited to speak so they can’t provide a different voice

Watch how Dawkins has to cut into his explanation at 8:25 to send them back. They are a distraction to him. And listen to how luke warm the applause is as they go back to their seats. They haven’t brought anything to this explanation. 

He then goes on to tell us that the paper, folded 50 times, would be some fantastical thickness but he doesn’t make use of the paper he’s just asked them to fold for him. You can see it sitting to his right:

So what was the point of using the volunteers? There wasn’t one. 

Just because folding paper is something you can ask a child to do and you think science presentations should have volunteers that isn’t sufficient justification to get volunteer children to fold the paper! It’s OK just to do it yourself as you explain its significance to your argument. 

I’ve written about Chris Bishop using his volunteer already so I won’t repeat myself again. Some people commented after that post that “people still like to get involved” and “offering that opportunity to a volunteer was generous” and I’d agree (and thank them for their comments) but that’s not enough of a reason to justify the cost of using any volunteer let alone this one. 

The time spent selecting, moving and instructing the volunteer, the loss of control as everyone clamours to get picked and the crashing disappointment they then feel having not been picked and the distraction as we are being encouraged to look at a volunteer as well as the balls isn’t outweighed by this volunteer’s presence. 

Worse, as with the Dawkins example, the actual explanation of what exponential growth is gets relegated when that should actually be the whole point of both demos. 

Compare that to David Suzuki’s explanation. The time it takes to select a volunteer is better used defining exponential growth:

anything growing steadily is called exponential growth and anything growing exponentially has a predictable doubling time.

Then instead of carrying out a physical demo we are asked to imagine a test tube filled with food for bacteria. 

The test tube and the food is our planet and the bacteria are us. I’m going to add one bacteria which will divide every minute. That’s exponential growth. 

At that point a single light is illuminated behind him. 

This is his demo and it’s going to go on behind him as he speaks. Mirroring what he explains verbally that one light becomes two, then it becomes four, then eight. We can see the number of lights growing exponentially. 

At the beginning there is 1 cell, after one minute there are 2, two minutes there are 4, three minutes there are 8, that’s exponential growth and at sixty minutes the test tube is completely filled with bacteria. 

He could have got two volunteers out of the audience to successively switch on double the previous number of lights (like Dawkins), he could have got a volunteer to come out and press a big red button to start the lights off (like Bishop) but he knows there’s no point. 

Not only could he do it himself (the volunteers wouldn’t be useful) the time is better spent making the best possible explanation he can that has the most impact. He doesn’t even draw our attention to the fact that the demo has started. 

So when is the test tube half full? he casually asks. 

I’ll give you a moment to think. Don’t scroll down until you have an answer…

And, of course, the answer is at 59 minutes. At 59 minutes it’s half full but at 60 minutes it’s completely full. So at 58 minutes it’s twenty five percent full, at 57 minutes twelve and a half percent full. 

This blew my mind. Forget paper folding or ping pong balls, with just some multiplying background lights and no volunteers to distract us we given the opportunity to get the reason why growth being exponential is so important. It is the amazing rate of change. 

You might have assumed (like I did even having watched Bishop and Dawkins multiple times) that the tube would be half full half way through the hour. But:

at 55 minutes of a 60 minute cycle the test tube is just three percent full. 


And look at all those lights. 

Suzuki is stressing exponential growth because of human impact on atmospheric pollution, Dawkins because of the survival of only the fittest and Bishop about Moore’s law and growth of computer processing power. 

They are all trying to get across the same point but Suzuki doesn’t risk muddying his message by using volunteers where they are not needed. As such his explanation is so much clearer and has a greater impact.  

The message of this post is very important. If you can’t think of a reason (beyond “wouldn’t it be nice…” or “isn’t that what we have to do..?”) to use a volunteer or if using a volunteer will cost more than it will bring in benefits then it’s OK to not use them. 

Using volunteers can be hugely effective but only if you follow the six reasons, to ensure they at least serve a useful purpose, and that they hopefully also promote positive emotions and add to the drama. 

Be like Suzuki. Have confidence that what you are saying or what you are showing is impactful enough. Don’t be like Bishop and Dawkins and fall into the trap of using volunteers where they aren’t helpful. It’s not good for your argument and it’s not fair to the volunteers. 




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