Piaget Water Level Test

Many years ago in a dentist's office I read an interesting article in a magazine. It talked about how there were questions that were specific to certain adult genders. In particular until puberty there was no measurable difference in performance on the question, but after puberty there was a large difference. As examples they offered a verbal question that women do well on, and a question where they drew two cups, one tilted, and asked people to fill in the water level if both were half full. (Artistry not required.) Men do well on this. Most women don't. And education doesn't matter, women who graduate college do worse than men who drop out of high-school.

I botched the verbal one due to something that looked silly to me, got the male one, and dismissed the article as garbage. Then a month later it came up in a conversation with my girlfriend, and she got the men's question wrong. I couldn't remember the one that women do well on. This made me curious, so I asked my mother the same question and she got it wrong. I can call my mother many things, but unintelligent is very much not among them. As an example, when she was at Stanford in the 50s they gave her a battery of ability tests. The only one she was not in the top 1% on was manual dexterity.

(Side note for married men. Do not rush to give your wife this test. I've started many marital fights that way, and I have never tracked down a question that women do better than men on. I know there is one, and I know that at 19 I couldn't do it, but I don't remember what it was and have never encountered another.)

Since then I've learned that this question is called the Piaget Water Level Test. The background on this is that Piaget found that children typically gain specific mental abilities at specific ages that are tied to specific growth spurts. And so he collected examples. For instance there is a specific age at which children learn that people who were not present would not have seen what they did, and another at which children learn that when you pour water into a tall thin glass you don't have more than you used to. And as he collected examples, he eventually offered the water level test. Which, oddly, men gain the ability to do during our last growth spurt, puberty, and most women never do.

I've seen various estimates for how well people do on it. One was that 90% of men can do the task, and only 30% of women. That seems to be a good fit with my experience.

An interesting side note. It is widely noted that there is a large gender imbalance within programming. But I've found through experience that programmers I know, whether male or female, have a 100% success rate on this question. I have no idea what to make of this tidbit, but I find it interesting.

Incidentally for those wondering what the answer to the question is, the water level is horizontal to the ground. The most common answer among women I've asked is to draw the water level parallel to the bottom of the cup. The second most common answer from women is to realize that there is a trick, and to draw the water level tilted twice as much as the cup. When the correct answer is pointed out, women recognize it as very obvious. I imagine that their feeling is much like how I felt after botching the verbal question that I blanked out of my memory.

BTW if anyone knows of any question with the reverse gender characteristics, I've been looking for it for over 20 years. It is frustrating - I know that at least one such question exists, but I've never found it.