Some things I use to test mental ability as well as train it are: BrainWorkshop (A free dualNback program), Cognitivefun.net (A site with assorted tests and profiles including everything from reaction time, to subitizing, to visual backward digit span), Posit Science's jewel diver demo (a multi-object tracking test), and Lumosity.com (brainshift, memory matrix, speed match, top chimp. All of these tests can be found for free on the internet).
Subjectively the regular use of these tests has increased my metacognitive and self monitoring ability. Anyone have other suggestions? How about tests one can do without the aid of external devices?
In complement to determining whether one's brain isn't in its best state there is the question of how to improve or fix it. Keeping with the general spirit of this thread, what are some strategies people use to improve their cognitive functioning (as it pertains to low level properties such as short term memory) in the short term without the use of external aids? A few I use are priming emotional state with posture, expression, and words, doing mental arithmetic, memorizing arbitrary information, and doing the above mental tests.
Second Brain Workshop; the dual n-back task is one of the few things which has any research suggesting it generalizes/transfers, and so is really interesting compared to random mental trivia tests like most of the stuff on Luminosity.
We all have our good days and our bad days. Due to insufficient sleep, illness, stress, distractions, and many other causes we often find ourselves far below our usual levels of mental performance. When we find ourselves in such a state, it's not really worth putting effort in doing many tasks, like programming or long term planning - as quality will suffer a lot.
The problem is - other than observing deterioration of results, I have no idea if I'm in such a state or not. I cannot be sure if it's also true for others, but I had to find out a few tests of what's my mental performance at the moment. Tests that are deeply flawed, so I'd request better if there are any. I also cannot predict my mental state in advance, as my life isn't terribly regular.
The most reliable test I found, and by accident, was fighting bots on a certain Quake 3 map - me vs 10 or so highest difficulty bots. The challenge was to get 50 frags without dying. As the map was huge and full of power ups, it wasn't really that difficult as long as I could maintain full alertness for 10-15 minutes - but if I was tired or distracted, I would invariably fail. This test was unfortunately extremely slow.
Another test would be to go to goproblems, and do a few random problems at proper difficulty level. If I could think right, I would do most of them, if I was tired, I would fail almost 100%. This didn't test alertness, I guess it would be best described as short term memory test, as that's what used for game tree exploration. Unfortunately what's the proper difficulty varies a lot with how much go I played recently, so it needs to be recalibrated.
One more test would be to go to some decent online IQ test like this one. My results on such test would suffer a lot if I was sleepy or tired. The main problem is that such tests cannot repeated too often, or I'd just remember the answers.
So these are three ways to test how well my mind functions at the moment, all testing something different, and all flawed in one way or another.
How do you test yourself?