There are so many movies and TV shows, and so many ways to access them, that it can be difficult to decide which ones will be worthwhile and which won't. If you're like most people, your friends and relatives are constantly recommending that you get involved in this or that TV show, or that you check out this or that movie. In general, you probably know what you like. If a friend recommends a show you know you will hate, you probably won't bother looking into it. Cop dramas are not for everyone, after all. But, with some exceptions, most of us have a pretty wide range of genres we'll consider, and a recommendation from a trusted source might even spur us to try something outside our comfort zones. So, if we have time to watch a new TV show or are wondering what movie to rent, how can we sort through 100 recommendations to arrive at the one that's most likely to please us? The principle of critical mass might provide one good answer. Although the term 'critical mass' could mean different things depending on the context, in this case, critical mass is a point when the number of voices in favor of a particular movie or show are so numerous that we just can't ignore them anymore. For example, let's say you have three friends, Bob, Sue, and Marsha, who regularly tell you about the latest series to catch their attention. In addition, you read reviews on five different websites. Maybe two of these websites also give you recommendations based on your individual ratings and viewing history. Just to make the situation more interesting, suppose your mom also likes to tell you about the shows she's watching, and she loves it when you get interested in something she told you about, because it makes her feel useful. Given this scenario, you can imagine that certain information would be more reliable than other information. For example, Marsha's recommendations might not be high on your priority list if you and she tend to have very different taste in television. You might value Sue's recommendations more highly if the two of you have a history of liking the same stuff. Sometimes, the factors determining how highly you value a certain recommendation are more complicated. Your mom basically only likes soap operas, which you hate, but since she's your mother it's sometimes hard not to give her recommendations a try just to make her happy. With the more impersonal sources, the case is similar. You're probably more likely to take a recommendation from a website that's accounting for your personal taste with some complicated algorithm thank you are to take advice from a random, snooty film critic (even if the critic is famous or well respected). With all these factors involved, it's easy to see how some movies and shows might reach critical mass well before others. If Sue and Bob, whose opinions you trust, rave about a movie, and then two days later it shows up on both of your online personalized recommendations lists, that might be enough to make you rush out and rent it as soon as possible. If your mom and Marsha both recommend the same movie, that might outweigh the more reliable recommendation, and instead you might consider picking a movie that got a good review from a couple of critics you like. Of course, there's no easy equation to plug all these factors into, but understanding the decision-making process in this way, could help out next time you're feeling indecisive about the hundreds of on-demand options available. If you can't decide between Movie A and Movie B, and if all other factors are equal (meaning you're not in the mood for one or the other based on genre or whatever else), ask yourself this―which one is, at this moment, closer to critical mass? Of course, neither of them has yet actually achieved critical mass, because if it had, you would have watched it already. It's likely, though, that one of these movies is closer to that point than the others, and that might be just as good a reason as any to give it a whirl.