What do you want to know? The methods are probably partially reproducible (though I'd expect high variance), but you seriously don't want to.
I was under pretty heavy stress during my whole childhood and early adolescence, and gradually lost things as a result (self-control in many areas, some intelligence, some memory). I was also a neat freak and hated e.g. showering in a dirty bathtub (plus some mild sensory issues), but normal habituation tempered that. In mid-adolescence I found a way out, but it blew up on me and I went depressed/emotionally numb for a few years.
At one point I started being completely unaffected by disgusting things I had to do, even though I consciously knew I'd normally be. At one point I was perplexed and went digging for something in a trash bag mostly as a test. Moral disgust was also decreased, but didn't completely disappear.
One or two years later, I also lost sorrow. When bad things happened, I felt indignation and anger and guilt and compassion and self-pity if applicable and all the rest of my usual reaction, but with a big gaping hole in the middle saying "Sorrow goes here". It was confusing.
A few months after that, I moved, changed schools, and started work on a big plans, with the expectation I would get better and regain some of the lost functions. Sorrow came back in a few weeks - I was mulling over an unrequited crush, noticed I was sad, and was happy about being sad for the day. Disgust came back sometime later, slightly more gradually.
Now I have about normal (though wildly varying depending on body awareness) levels of disgust. My reaction to bad things has changed (roughly, I want to fight, not mourn) so it doesn't include sorrow, but it doesn't feel like "Error: emotions/sorrow not found" either. I think I could train to feel sad about bad events, but it doesn't seem productive (I'm prone to self-pity). Sorrow is a pleasant emotion, a kind of luxury, to revel in over a crush or after a play with failed heroic sacrifices - not appropriate for 150000 deaths. Obviously this comes from my glee over getting sorrow back.
Interesting.. Thanks for the reply.
I think I'll pass on replicating it :p
Follow-up to: Suffering as attention-allocational conflict.
In many cases, it may be possible to end an attention-allocational conflict by looking at the content of the conflict and resolving it. However, there are also many cases where this simply won't work. If you're afraid of public speaking, say, the "I don't want to do this" signal is going to keep repeating itself regardless of how you try to resolve the conflict. Instead, you have to treat the conflict in a non-content-focused way.
In a nutshell, this is just the map-territory distinction as applied to emotions. Your emotions have evolved as a feedback and attention control mechanism: their purpose is to modify your behavior. If you're afraid of a dog, this is a fact about you, not about the dog. Nothing in the world is inherently scary, bad or good. Furthermore, emotions aren't inherently good or bad either, unless we choose to treat them as such.
We all know this, right? But we don't consistently apply it to our thinking of emotions. In particular, this has two major implications:
1. You are not the world: It's always alright to feel good. Whether you're feeling good or bad won't change the state of the world: the world is only changed by the actual actions you take. You're never obligated to feel bad, or guilty, or ashamed. In particular, since you can only influence the world through your actions, you will accomplish more and be happier if your emotions are tied to your actions, not states of the world.
2. Emotional acceptance: At the same time, "negative" emotions are not something to suppress or flinch away from. They're a feedback mechanism which imprints lessons directly into your automatic behavior (your elephant). With your subconsciousness having been trained to act better in the future, your conscious mind is free to concentrate on other things. If the feedback system is broken and teaching you bad lessons, then you should act to correct it. But if the pain is about some real mistake or real loss you suffered, then you should welcome it.
Internalizing these lessons can have some very powerful effects. I've been making very good progress on consistently feeling better after starting to train myself to think like this. But some LW posters are even farther along; witness Will Ryan:
Some other LW posters who've made considerable progress on this are Jasen Murray, Frank Adamek and Michael Vassar. I invite them to post their experiences in this thread, and in future posts of their own.
How does one actually achieve emotional acceptance? It is a way of thought that has to be learned with practice. There are various techniques which help in this: I will cover one in this post, and others in future ones.
Mindfulness practice
Mindfulness techniques are very useful in realizing that your thoughts and emotions are just things constructed by your mind:
It also has clear promise in reducing suffering:
I recommend the linked paper for a good survey about various therapies utilizing mindfulness, their effects and theoretical explanations for how they work.
While I haven't personally looked at any of the referenced therapies, I've found great benefit from the simple practice of turning my attention to any source of physical or emotional discomfort and simply nonjudgementally observing it. Frequently, this changes the pain from something that feels negative to something that feels neutral. My hypothesis is that this eliminates an attention-allocational conflict. The pain acts as a signal to concentrate on and pay attention to this source of discomfort, and once I do so, the signal has accomplished its purpose.
However, often I can do even better than just making the sensation neutral. If I make a conscious decision to experience this now-neutral sensation as something actively positive, that often works. Obviously, there are limits to the degree to which I can do this - the stronger the discomfort, the harder it is to just passively observe it and experience it as neutral. So far my accomplishments have been relatively mild, such as carrying several heavy bags and changing it from something uncomfortable to something enjoyable. But I keep becoming better at it with practice.