We think young people have a lot more sex than they actually do – and men have a particularly skewed view of the sex lives of young women. As part of Ipsos’ long-running studies on misperceptions – we asked people in Britain and the US to guess how often people aged 18-29 in their country had sex in the last four weeks.

The average guess about young men in both countries is that they had sex 14 times in the last month, when the actual number is just five in the UK and four in the US, according to detailed surveys of sexual behaviour.

Our guess would mean that, on average, young men are having sex every other day, around 180 times a year, compared with the more mundane reality of around 50 times. That seems a ridiculous enough guess – but it’s nothing compared with how wildly wrong men are when they guess about young women’s sex lives, in both the US and Britain.

Men think British and American young women are having an incredible amount of sex – 22 times a month in Britain, and 23 times a month in the US, compared with an actual of around five times. 

These guesses would be the equivalent of the average young woman having sex every weekday, plus two or three times on one special day each month. Why are we so wrong? As with so many of our misperceptions, it will be both how we think and what we’re told. 

Our brains are wired for sex – the survival of our species literally depends on it. But it is a hotbed of mispercep­tions – because unlike many other core human behaviours, where we can get a better idea of social norms from observation, sex mostly happens behind firmly closed doors (and the sex that is available for general viewing is not a fully accurate representation of the norm).

Because we don’t have access to very much real-life com­parative information, we turn to much dodgier sources: playground or locker-room chat, dubious surveys, salacious media coverage, TV shows (even if Love Islandtoned the sex down this year) and porn. These provide extreme examples and anecdotes that distort our views of reality.  

It’s in that space that misperceptions breed. For example, many of us still sniggeringly hold on to the belief that there is a link between shoe or hand size and penis size. Tragicomically, this became an actual discussion in the US presidential cam­paign in 2016, with Donald Trump’s supposedly small hands being linked to other physical ‘inadequacies’. But he needn’t have been so defensive: numerous serious academic studies have tried to find a link between penis size and hands, feet, ears, and a host of other body parts – and they can’t find any correlation.

The largely unspoken importance of sex also leads to widely believed but false claims about how much of our mental energy it takes up.

For example, the trope that men think about sex every seven seconds has also stuck in our heads – but think about it: that would require thinking about sex 500 times an hour, or 8,000 times during a waking day. Given that psychol­ogists believe that people are generally incapable of genuinely ‘multitasking’ – that is, they can hold competing ideas in mind sequentially, but not simultaneously – so many sexual thoughts would leave little space for anything else.

Although it is very difficult to identify precisely what we’re thinking about a lot of the time, and counting it accurately is even more challenging, several academic studies have put men’s ‘sexy thoughts’ closer to around 20- times a day – which still sounds exhausting to me.

Our misperceptions reveal a lot about how we see the world. They are a brilliant clue to our deep-seated biases, as our guesses at what is ‘normal’ are more automatic and unguarded. 

In this study, these guesses point to some frighteningly wrong views of young people and women, particularly among men. It’s not clear whether this is down to wishful thinking, media-driven images or just a sense that we’re missing out while women can get sex whenever they want – but that doesn’t really matter.  The important point is it’s a signal that men still see women very differently when it comes to their sex lives.

As with other misperceptions, the answer is not just to bombard people with more facts to correct these views, but to deal with the underlying causes. We still have a long way to go for men to have a grown-up view of women’s sexual equality. 

The Perils of Perception – Why We’re Wrong About Nearly Everything is published by Atlantic Books on 6^th September 2018.