When discussing achievements a couple of posts back, I mentioned they have more to do with goal forming than anything else. When a player plays a game, her first goals are typically to learn the game, proceed through its levels (or whatever) and finish it. There are of course various sub-goals while playing. Achievements or trophies often come into play afterwards and collecting them is another goal. It can also be argued that good trophies are ones that give the player some clear additional goals, which will increase the longevity of the game and therefore improve its value for money ratio. Case in point, before we had these modern consoles with their trophy or achievement systems, Star Ocean 3 had built-in battle trophies. It took me about 50 hours to finish the game, and then I spent another 250 or more hours collecting trophies (I'm still missing 7 out of 300).
In general, a good trophy challenges the player to play the game differently, introducing more difficulty. In Mirror's Edge there is a trophy that requires you to not shoot a single shot during the game. BioShock rewards the player for playing without resurrection chambers turned on. And of course Star Ocean 3 rewarded so many different and interesting things that it kept me hooked for a long time. Typically the only reward is a reminder in your account that you've gotten the trophy, although some games (like Final Fantasy XIII) hand out some minor gifts like operating system themes for getting trophies. Bad trophies are the kind that just require the player to do some repetitive thing a lot of times. More of the same is not very interesting, but doing the same thing differently can be.
Now, let's exit games for a while. With interfaces, especially in interactive spaces where interfaces can be abundant, it is important to get the users to form the right goals. By this I of course mean we need to assist them in forming goals that are relevant to them, assuming they are using our interfaces at leisure. In a work situation on the other hand we might want to introduce reward schemes that support effective work. Regardless of situation though, it's useful to keep the requirements of flow in mind: the user cannot achieve flow if he cannot set goals. So even before thinking what kinds of goals our interface should support, it needs to support goal forming in general. It can then be useful to do some research on what kinds of goals a prototype inspires in people, and then think how they could be adjusted, if necessary.
When the overall goal of an activity is fixed, the system should aid users in forming sub-goals that help them move towards the overall goal and stay motivated. If the activity can be split into a plethora of short-term goals, progress is easy to measure, and if there is flexibility in task order, users can also select short-term goals that are a good match for their current skills. In general, people split activities into short-term goals all the time when working but it definitely cannot hurt to make systems that support keeping track of these goals, and that can also suggest goals.
Before achievements and trophies entered the life of gamers, people used to make up their own challenges. These were definitely no less interesting, but of course no one was certain whether a challenge would be possible at all until someone completed it. With formal trophies, game developers can design the challenges and ensure that they are indeed possible to reach (although, some of the craziest ones are almost unreachable). So for example, in order to improve my writing, I could use a text editor that has various trophies for using language in special ways, like "use 5 different synonyms for a common word in one article". Of course I can make up all these challenges myself, or search the internet, but if it is in fact built into my interface, they are constantly present and easily available for viewing.
Overall, goal forming is a highly relevant topic for user experience. I have once again just scratched the surface, but already discovered at least two important aspects of it. The first one is to gain an understanding of what goals users can form when using your interface. The second one is guiding users to form goals that are constructive towards the overall goal of a larger activity. If every phase of an activity can has its own short-term goal, the user experience is likely to improve. This is too often not the case when viewing the learning curves of more complex applications.