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As we all know, snark always comes before a fall. Mea culpa

One snarked and, inevitably, fell

Now for the science bit

Yet when we ask people about how much we should spend on cleaning up pollution to stop one person dying we end up with entirely different answers: there's one EPA regulation on a carcinogen which costs $5bn per life saved, yet people seem quite happy with this. The neuroecconmoic answer is that when we ask people to value things outside the daily experience of valuation, then they will say things which are entirely different from their actions in daily life in actually valuing things.

That is, revealed expectations – what people actually do – are frequently different from expressed expectations, or what people say about things they've not had that direct experience of valuing. The reason for this is that people are using different parts of their brains to do those two different types of valuations.

This is where I snarked and fell, of course: pointing out that we can just ignore those expressed valuations. But Paul Glimcher, the neuroeconomist at issue here, points out that this is not necessarily so. We could say that it is so, certainly, but we could also say that both valuations are equally valid, given that they are both being made by humans and that's what we're trying to study – what valuations do humans put on things?

This is not the only thing that this new blend of sciences can tell us. There are times when what we know about how humans act in an economy tells us things we didn't know about how the brain works. That's a bit beyond my comfort level, but working the other way around is interesting.

For example, there's a famous experiment where people are invited to taste jam in a supermarket. When there's 24 varieties everyone says “Oooh, yes, that's lovely!” but almost none of them buy any. When there's only six, then more people buy one or other of them. This has led to all sorts of people insisting that choice is bad for us and, obviously, let's stop this obviously wasteful free market. But the neuroscience of how humans make choices leads us to the neuroeconomics of what this result is really about.

When we make a choice, the neurons in a certain area of the brain fire off and that's what makes the muscles move and so on. But before those neurons fire we can observe – with MRIs and the like – that if there are a number of choices possible, then a similar number of different neuronal areas will have a rise in activity. It is almost as if the brain is priming for choosing between the alternatives: if there's three possible choices, then three areas will “warm up”. It's when one of them passes the trigger level that the action is, umm, triggered and that triggering in itself suppresses the activity in the other potential areas. It is the triggering which is the decision, which causes the action itself. Err, yes, not a tehnical description but still...

What we find is that human brains can handle about six alternatives for action. We have not found (at least, among the variations in brains so far studied) people who have eight or 24 little areas warming up before the decision is triggered. Six seems to be our lot. If there's more than six choices, it frequently leads to no decision being triggered: we'll buy more jam if there's six choices and less if there's 24, as with 24 we never fire off any one set of neurons that say “Buy!”

These numbers are, by the way, confirmed in a number of different experiments and six really does seem to be the number from both ends: from the empirical experiments with people and purchases; and with choices as seen through looking at neurons in the brain when making decisions.

This does not mean that choice should therefore be restricted to six of everything. For two reasons: what is the “everything” that there should only be six of? Jams? All spreads, including Nutella etc? All things we put on bread, so including Bovril and Marmite? And further, who the hell gets to decide which six things should be included? But it does give us an interesting insight into why Aldi and Lidl, with their very much smaller SKUs (ie, types of different thing) do so well against the traditional supermarkets offering multiple types of everything.

Next page: Take that, Marx!

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