Can you remember back to a time when fizzy drinks weren’t maligned, but instead a rare treat? When you and your eagle-eyed siblings watched over the soda pouring ritual with great intent, studiously making sure the levels were equal, and that no one was preferred (by so much as a drop)?  

Back in the early 1970s, more often than not the fizzy liquid came from a soda syphon and was mixed with cola syrup. But it was a still a precious treat. And on the rare occasions when the groceries included The Real Thing, the measuring had the accuracy of a spirit-level.  

Of course, there are many households today where soft drinks are still carefully dispensed, and not binged-on by the half-gallon.  And though this may be more for reasons of health than thriftiness, the soda-levelling ceremony remains a familiar ritual.   What might not be so well known is that it can be used as a measure of a child’s emotional intelligence.  

Very young children are driven by a need for equality.  

When two children are offered a choice between, on the one hand, two half-full glasses of the cola delight or, on the other, one full glass and one glass that is three-quarters full, but with no certainty as to which child will get which glass, younger children will invariably go for the first option. Equality rules.  

As children get older, the outcome is reversed. The risk of getting relatively less is outweighed by the certainly of getting absolutely more.  

Bigger is better even if it’s not biggest.  

Perhaps there are some lessons in this for us grown-ups.  

Of course, soft drink inequality is not an issue for adults. As we know too well, many - including among the least well-off - consume more of the sugary drink than is healthy.  

But economic inequality remains a burning issue. And it’s an issue we are currently researching at The New Zealand Initiative.  

However, like children and their fizzy drink, if we can find a way for everyone to be better off, should it really matter that some may do relatively better?  

A risk of aiming for equality is that everyone’s glass ends up being half full. If we dampen the incentives to excel, the danger is no one will.

Perhaps on this we could take a lead from our children.