Decisions are one of the aspects of a roleplaying game that really make it interesting as a pastime. Everyone will have different reasons for wanting a specific path followed, and they will all have a different response once the path is taken.
There are a few types of decision points; there may be two possible outcomes or more, there may be specific outcomes that seem favourable in the context of the game mechanisms, the simulation or the narrative. For the moment I'll focus on a couple of simply balanced binary decisions. These have two possible outcomes and each is just as likely to occur.
Like a Perfect Mirror, a purely balanced binary decision point is virtually impossible to achieve. Players will always have a bias for one particular option (conscious or unconscious), and there will always be the possibility of other decisions which hadn't been considered.
In game design, a balanced decision point typically comes into play when dealing with something arbitrary; skill factors don't play a role, player's intentions don't factor into the situation. An example might be a simplistic random encounter chance. Flip a coin, on a head something bad happens, on a tales then the scene is unaffected by external threats.
In scenario design, a balanced decision point is much the same. Two chests are offered, in a situation where it is impossible to tell the difference between them. One is trapped and will kill the whole room, the other holds treasure. Which one do you open??...no, actually like most dilemmas, that ends up being a trinary decision point (left chest, right chest, move along opening neither of them). Truly picking a well balanced binary decision point is hard. In my years of gaming, I've read a lot of old scenario designs where two choices are offered, and if players try to choose a third option, their story path is diverted back to one of these two options by use of mirrors (often imperfect ones). Perhaps the module sets up so that the players are faced with making a decision between two outcomes, and if they choose a third option the whole scenario will be derailed. It's a rookie mistake, and most GMs only make it once or twice before they learn to allow for expanded possibilities.
You also need to consider the loading on the decision. By their nature, people don't like making decisions blind. They like to gather a bit of information before they make their call. Jurors are expected to weigh up the evidence and the testimonials before they make their call for innocence or guilt. Soldiers like to know their ropes are sturdy enough before rappelling down a cliff-face. Gamblers consider the form of sportsmen or animals before wagering their money. Even in something as purely arbitrary and random as a lottery, people will have a prejudice toward certain numbers for emotional reasons. To keep a decision point balanced, every "pro" needs to be balanced by a "con". It's not a good way to set up a dramatic decision point because the answer will always be a 50/50 decision. I've always thought that 70/30 decision points are better, and 90/10 decision points are better still, because there's always that chance for the minority to win (which makes for much better drama).
In many games, I've seen GMs introduce the concepts of a binary balanced decision, and in many cases the players accept this and run with it.
The GM grabs a die. "If it rolls odd, this happens; but if it rolls even, that happens."
This is something out of the players control, so they fell a bit more comfortable with the fact that they can't play with the probability of the situation. They simply hope that the can maximise the benefits if a good event occurs, and pray that they can avoid the worst if a bad event occurs.
It's a valid GM technique, and it allows a bit more spontaneity in a situation than you might find in a rigidly designed scenario. It certainly isn't perfect, and as long as the playing group all agrees that they aren't aiming for "realism" with a mechanism like this, it can blend into the background as a game tool.
I would never use it to determine an outcome when something as dramatic as a character death is at stake.
I've also seen players introduce this type of mechanism into play through their characters. Such events typically occur when playing someone who has lost their ability to think rationally, and they have a pair of immediately obvious choices (eg. Fight or Flight). The character can't think straight and is unable to use their skills or established thought patterns to their advantage. It doesn't matter too much whether this disrupts the storyline (especially if this method of play is being employed by everyone at the table), a good GM will be able to run with it...and it tells us a bit more about the character. Once rational thought takes over, the player an help to consider the events that might have gone through the character's mind (and in turn, complex game mechanisms take control of the system again).
Recent thoughts about game design have even pushed the concept of the binary decision to a metagame level..."Say YES, or Roll the Dice". I'm not saying to flip a coin to determine whether you say "YES" or whether the dice come out; I'm simply saying that there is a decision point within a GMs mind. This is a point where they consider what tactics might be better used to push the game play onward.
This blog is a meander through my interests in and around the world of independent roleplaying. Due to spam bots I authorise people's responses to the posts here, so if your reply doesn't appear straight away, don't get frustrated. You might just need to wait a couple of days for me to log on again. If you're really passionate about your reply, send me an email and I'll make sure that your message gets through.