Game description: The kid has a multiple choice question. If the answer is wrong or right they procede to the next question and so on.
The question: Is it good or bad user experience for kids, if I show a timer and limit the question by time?
The kids' age is 6-14.
That depends on the goal of the game. I assume it is educational in nature, so the question then is whether you are trying to test or encourage speed in answering or simply trying to get the kids to learn something.
If the goal is linked to speed (like say the multiplication tables), then I would say that it is acceptable to include some sort of timer. I would however try to make it less distracting by simply changing the background or the sound when time is starting to run out. Showing an actual clock may prove to be too stressful and distracting.
If the goal is for the kids to learn something, then I don't see any real added vale in adding additional time stress on them. Let them learn at their own pace, and reward correct answers, not the time taken to come to them.
I believe a counting timer puts a lot of stress, both kids and adults. It draws the attention, and emphasizes the time limit. In some situations it could help boost excitement, and feeling of competing against time, like you see sometimes in TV shows.
This draw this conclusion after some experience in developing and conducting psychological experiments, where this kind of question often arises.
It depends what you're trying to teach the kids 6-14 years of age.
Both ways are "correct" in a sense, since kids usually have no problem understanding the timer issue in games. But I guess you have the answer in your game objectives or scope of the game.
As a side not the timer issue is more frustrating for adults than kids on Donkey Kong II game from 1983:
From my observation (well, the initial part may be not very much about UX, but I have two daughters as well, and a lot of friends with children in the same age) children at the age of 6/7 start being more oriented on results than before. For younger children, the higher you put the difficulty, the less they will be interested in continuing the game. When they are 6/7, and definitely later, they will find the time limitation additional value of the game, because it becomes more challenging. Of course it may be not a rule, but this is what I have observed.
The other aspect is that technological development triggers a lot of changes in users behavior. When I was a child, I was actually happy to play any electronic game. My favourite was poker (I still have it, can you imagine!). I played it when I was 8 or 9, so pretty soon for a card game, I think. Now the availability of games is so high that it's easy to switch to another one and play it instead of the hard one. This is what I can say about my younger daughter whan she plays on my iPad (4 yo), whilst for the older one (7 yo) this threshold is put way farther.
Having this in mind, my answer will be:
The two seem to say the opposite, but you can achieve both by using the timer for giving premium points. Let's say, user has unlimited time for the answer, but if he answers within 10 seconds, he is given premium points. The number of these points could decrease within these 10 seconds, from e.g. 100 to 0, staying at the 0 level after the time is up.
I think you should also focus on introducing some difficulty adjustment in the game. Depending on the age of the player, he or she may find the same quiz more or less challenging. You can make these adjustment automatic (based on age) or manual (based on user selection of easy/medium/high).
