OK I haven't thrown the test out of my sandbox just yet.
I tried it a couple more times, trying to respond how I imagine different imaginary characters would respond.
The first time I tried to answer as someone who doesn't rock the boat much, works well at a steady job, does what their boss tells them to without complaining, believes most of what mainstream media and conventional wisdom tell them, and is generally happy, doesn't take themselves too seriously, and easy to get along with. I got these results:
Mature 37
Neurotic 9
Immature 12
The second time I tried to answer the questions as I think a particularly neurotic person would, and got these results:
Mature 34
Neurotic 19
Immature 41
However, I found trying to give neurotic answers was difficult, as I would be split between trying to answer as I thought that kind of person actually acted, and how they probably thought they would answer it, maybe not being very honest with themselves, e.g. with the following question:
"I'm usually able to see the funny side of an otherwise painful predicament."
I can imagine a person choosing answer 9=strongly agree, when to other observers describing that person, they might place that person at the complete opposite end of the scale in terms of them being able to see the funny side of a painful predicament.
Similarly with the question "I can keep the lid on my feelings if letting them out would interfere with what I'm doing."
Someone might choose 9=strongly agree, while to other observers that person might be someone who it seems their feelings are entirely running the show.