First up we have Fodder's idea: A way of thinking about love and hate can be something like a score which ranges from -100 (you actually want to kill the person) to +100 (you love the person so much you'd die for them), and people who you are completely indifferent to are a 0. So a person has a base score which can be adjusted but certain things you do can also give you a timely positive or negative bonus (i.e. you can have a base score of 40 but because you just punched them in the face you've got a -80 score added to that). What I like about this way of mapping things out is that it nicely allows for variation in people. So if you're a fickle person a +30 could be "love" and a -10 could be "hate", or if you're someone who generally dislikes all people, 0 could already be in your hate range.
The idea implies that love and hate are two sides of the same coin, and in essence, that you can't love and hate someone at the same time. Supposing this is true it makes it very easy to explain the transition people have from love to hate (and back again). Personally I don't have any issues with this idea's implication either. Even if I love someone, if they do something that makes me "hate" them I don't feel both love and hate at the same time, but once I cool down the "hate" goes away and the love feeling comes back. I know that it is possible to hate and love someone at the same time, but I've never personally experienced the feeling before, nor have I ever seen anyone that does. Also, supposing that it is possible it could be described as someone's score rapidly changing.
Jeffro's idea: Jeffro points out that moving from love to hate can be attributed to a number of different ideas. It's best explained when you think of the situation where you're in a relationship with someone and enjoying it, and then they break up with you. At first there's a bit of confusion because you need to try to adjust your feelings from liking them to not liking them. The part I find most interesting is the idea that the anger can come from a means of self protection: because they've broken up with you they have some kind of emotional influence on you and so to disrupt this emotional influence you force yourself to hate the person.
This ties in very nicely with Fodder's idea, the person you liked was say around +70, but then because they broke up with you, you try to bring them back down to something lower, say +10. To do this the easiest way is to add quite a few "hate" bonuses to the base score to bring the current feeling down and adjust the base score. In essence these two idea combined really help to explain the concept of loving then hating someone.
Another concept brought up during an IM I had involves looking at how people remember things. Humans are quite terrible at remembering the specifics of an event, instead it's very good at remembering enough to get the important information across when you "look up" an event in memory. Because of this what the brain *does* remember very well are the emotions you felt around a certain event, and if you felt strong emotions during an event, a person's brain is also likely to treat the event as a particularly important and therefore record more details about it. A good example of this is a first date. Most people remember their first date with a partner quite clearly, yet would they remember what they did on their 4th, 5th, 20th date? Since the brain stores information in this way when you're with a person you like the details don't become important, what is important is the feeling you get while being around the person. So then what happens when the feelings change?
I personally love this example, probably first of all because it's a bit more scientific and so I see the evidence as being a bit more concrete, but largely because I can personally relate to it, and I've seen a large number of examples which fall within this model. To me spending time with my girlfriend doesn't mean we have to do something special, what I enjoy most is simply being with her and how I feel when I'm around her. On the other hand this idea beautifully explains how some couples break up. Two people have been going out for a while but something happens and the feeling drastically changes and so they break up. The other way to look at it is how couples stay together. The couples that stay together are the ones that can look at both the feeling and the details. Sure something bad might have happened but those who can look at the relationship as a whole and judge whether it's worth loosing everything they have over one incident are a lot more likely to be successful.
As a side note: I wonder if that means a relationship is likely to last longer if the people involved are less emotionally attached to the relationship, however in that case would those people enjoy the relationship as much? I wonder if you could graph something like the success of relationships based on emotional investment/length of an enjoyable relationship.
The last idea for today is look at emotions from a completely biological point of view. Most feelings, including emotions, are regulated simply by chemical releases in the body (which are controlled by the brain). It starts getting interesting when you look at it from a homeostatic point of view. Homeostasis is in essence the body's ability to keep itself alive, it includes functions like keeping your body at a set temperature and ensuring that you have the right amount of water in your body. This actually plays a very very large factor in the way humans and animals behave. For example, say you don't have enough water in your body: you can go through all these really complex processes to try and keep the water that you currently have in your body, but the easiest way to take care of things by far is to simply feel thirsty. Feeling thirsty will cause you to seek out water, and hence, directly affects your behaviour.
Loving someone is no different, the feelings of love that humans experience are a mix of feelings that the body itself produces. These feelings are also passed down genetically, making the need to love someone somewhat instinctive, or at the very least the need to reproduce is. When you think about it this way, Fodder's model works perfectly: a person you don't know produces no feeling (0 points) and someone you like can automatically cause your body to produce a feeling (+ve base points). What happens around you can cause reactions in your body which produces +ve or -ve feelings in response to a person.
Anyhow that's enough for me for one day. If anything seems unclear, doesn't make sense, or you just want to talk about what I've written feel free to talk with me by the usual means. I also want to thank those who have taken the time to either comment on my blog or talk to me in person about these ideas.