Current data suggest that Avengers: Infinity War is well on course to being Marvel’s biggest UK hit to date. Given how many successful movies Marvel has produced over the last decade, that’s really saying something.

But the current glut of superhero movies has led to many complaints that studios are playing it “too safe”, and that the viewing public aren’t being challenged by anything new.

Why, though? Not “why do studios play it safe?”, that’s obvious; films are expensive to make and lose ridiculous amounts of money if they flop. The question is, why are films featuring well-known characters doing their usual thing in moderately new ways considered “safe” in the first place? Shouldn’t we grow tired of this repetition, rather than keep demanding more?

It’s not something limited to cinema; countless Radio and TV shows have proven ridiculously enduring by sticking to the formula, “familiar characters/personalities doing familiar things in relatively new ways”. Even The Simpsons – despite the recent scandal and constant complaints that it peaked long ago – keeps getting renewed, so ample people are clearly still tuning in.

It’s even true in the ever-competitive music industry. Innumerable new bands release singles and tracks every day to barely a shrug, but the Abba announce a new song and everyone loses their minds.

But, why? Why not take a chance on something original? Why do so many keen and talented newcomers struggle to get their ideas made or noticed while familiar entertainments keep getting churned out and lapped up? There are countless answers to this question, but one factor is likely to be the nature of the human brain, and how it determines what we like and what we don’t like.

One interesting aspect of how we decided this is that we, and many other creatures, show a preference for both familiar things and novel things. There’s the “mere exposure” effect, where we respond more positively and tend to like things we’ve seen before over those we’ve not, but also novelty preference, which is basically the exact opposite. That the brain is capable of two contradictory things is hardly unusual, different situations often call for totally different responses after all. Applauding a wedding speech is perfectly normal; applauding a eulogy is not.

But further confusion is introduced when you consider that both familiarity and novelty can be unpleasant. Something too familiar, too well known, risks losing all appeal and becoming boring, due to processes like habituation. By contrast, something too new, too unfamiliar, can often be unsettling, even disturbing, partly because it introduces a lot of uncertainty, which is stressful for the brain. So, the brain both likes and dislikes familiarity and novelty? How does this make any sense?

As is often the case, the truth lies in the grey areas between these sweeping statements, and often context is key. For instance, with regards to novelty preference, the liking of something new, studies have shown that there are distinct neuronal circuits that control our anticipation of reward, and our detection of novelty. However, activity in both combined results in greater activity in the reward pathway, causing us to experience more pleasure and happiness.

You’d be forgiven for reading this and concluding that it means novel things are more pleasurable than familiar ones, but that overlooks the other part of the system; that of reward anticipation. Put simply, it argues that novel things are a more rewarding if we’re confident they are pleasurable or enjoyable in some way. And to know something is rewarding, we have to know enough about it to be able to make this judgement. Ergo, it must be familiar, to some extent.

Your long-term partner unexpectedly appears at the door and presents you with gift-wrapped present, that’s a very pleasant surprise. But a stranger appears at our door and does this? That’s terrifying.

There’s also at least one other study which suggests that, as well as novelty detection, reward anticipation is influenced by another neurological system that calculates how much effort something requires in order to obtain that reward. If the anticipated reward is not deemed sufficient to justify the effort, our underlying systems seemingly alter or very perception to discourage us from doing or engaging with it.

You can easily see how this would heavily influence our choice of entertainment; a sequel or follow-on to a film you’ve previously enjoyed is likely to be high in reward anticipation (“I enjoyed the last one and this looks very similar) and low in effort required to engage with it (“I already know these characters and settings so don’t need to learn anything new”) but with sufficient novelty to not prove boring or repetitive (“I wonder what scrapes they’ll get up to this time?”).

On the flip side, something totally new and unfamiliar is going to meet more of a challenge in these instinctive calculations; you don’t know how good it’s going to be, how much you’ll enjoy it, and you will have to work out who everyone is and what’s going on. Not to say new entertainments can’t entice people in, it’s just they often have more work to do, while the old and familiar gets a lot more leeway in the brain.

As ever, the truth of the situation is a lot more complex than this simple summary. Different things and situations cause different outcomes in the brain when it comes to familiarity and novelty preferences. All things being equal, ever-social humans invariably find familiar faces more appealing than unfamiliar ones (which explains why we stick to familiar people in our entertainments), and we’re also often very cautious about novelty when it comes to food; it’s one thing to passively watch/listen to something new, it’s another thing to take it into our very bodies. On the other hand, jokes and humour often depend entirely on novelty, as a familiar joke very quickly loses any potency.

There are plenty of other factors to consider here, of course, particularly when it comes to choice of entertainment. Everyone is different, and many enjoy the effort and discovery of new things while finding the familiar tedious and tiresome. Influences of the culture and industry are also big parts of what’s liked and what’s actually offered. And even if you do want to utilise familiar properties in novel ways, it can be a tricky balance to get right, as the Star Wars prequels, Matrix sequels, and remakes of Robocop and Total Recall reveal only too well.

Basically, the typical brain likes to experience new things within a familiar, and therefore safe, context. A comfort zone, if you will. But that doesn’t mean that’s the only thing it likes. And sometimes safety leads to stagnation. And that’s not enjoyable.

• Dean Burnett looks in details at why we like the things we do in his new book The Happy Brain, which is similar to his last book but somewhat different. It’s available now at The Guardian Bookshop for £9.99, £3 off RRP.