it's a mystery, and I'm not being sarcastic, I'm a psychologist with neuroscience studies and we really don`t know. any hypothesis? well, it seems that what we call "funny" is somehow related with the same process that lead to the sensation of surprise, we are programmed to pay attention to unexpected things (which requiere some grade of tension) but when the final result of an unexpected situation is absurd (and harmless) then we laugh as a sign of relief of our attention system.
Are there any strange fears or mental disorders that exist only in specific
Its called "culture-bound syndrome," and you can find a list here!
One of the problems, though, is that the way we interpret many illnesses is at least partially cultural. When it comes to things like phobias (fears) and anxiety, you kind of have to know what you're scared of and it has to fit into your understanding of the world. For example, some cultures place a lot of emphasis on the family. As a result, you see a lot of fears around letting others down or disappointing others (versus letting yourself down).
If your really want to look at extremes, look into different cultural explanation of psychosis. Is it a medical condition? A religious experience? A sign of witchcraft? Who is more right or more wrong?
Is there a psychological reason we recognize happy/sad melodies, or is it just that we're used to the context?
What is mental energy, and why do depressed people have none of it?
Not so long ago major keys were considered 'happy' and minor scales considered 'sad'. But it has been determined that that is just conditioning.
Also in music there is the idea of tension. Try singing the first 6 notes of Twinkle Twinkle Little Star, leaving of the seventh ("star"). That distinct sense that the melody has been left uncompleted is tension, and the seventh note is thus said to "resolve" the tension. Always resolving the tension makes for more positive effects of the listener, so nursery rhymes will reliably always resolve tension.
Here we run into one of the common problems. We both know more or less what "mental energy" is in terms of what it feels like, but it's still just a construct. Does it correspond to a clear and obvious thing in the brain? Eh, maybe. Let's consider a few related and overlapping but not-quite-the-same concepts:
- Arousal/wakefulness. Are you feeling alert and awake, or unfocused and tired?
- Motivation. Do you feel a desire to do things, or not?
- Cognition. Can you think clearly, or does your brain feel foggy?
All of these are similar, but could be affected separately. Let's say I took a big dose of Benadryl (diphenhydramine.) Its blockade of histamine receptors would lead to decreased arousal and wakefulness, while its blockade of muscarinic acetylcholine receptors can impair cognition. My motivation might still be fine, though, so while I might have more difficulty doing anything given my sleepiness and fogginess, I'll still want to do something.
Likewise, all three may be affected in major depression and related disorders. Arousal could be low, but it could just as easily be too high--anxiety is a common feature. Motivation, interest, and cognition are all often impaired. Of course, sleep disturbances being a common symptom, lack of sleep won't help any of the above.