IF you want to get close up and personal with any culture – at home or abroad – jump on a bus. From a sociological perspective, the bus experience offers plenty of bang for your buck. The microcosm of the bus – especially when crowded – reveals more than any guide book can about a city’s collective psyche and their attitude towards personal space.

In Madrid, following a campaign led by a feminist collective called Women At War, "manspreading" on buses is now officially deemed socially unacceptable. "Manspreading" is the splaying of legs wide apart, whereby the male passenger colonises two seats instead of one. Some 10,000 people in the Spanish capital signed a petition and submitted it to the city council, who have now taken the issue seriously by placing signs on public transport to discourage such public expressions of machismo.

Women in the city claim they feel intimated by "manspread" and see it as an act of micro-aggression. They are no longer prepared to make do with the meagre slice of seat remaindered by their fellow male passengers. New York has run a similar campaign on their subway system since 2014, with a simple slogan and sticker: “Dude … Stop the spread please. It's a space issue.” The accompanying visual depicts anonymous red sticker man, legs splayed wide apart across two seats while two other grey-coloured passengers have to stand due to red sticker man’s gross sense of entitlement.

The ad campaign being rolled out across Madrid is similar, but the text reads: “Please respect the personal space of everyone on board.”

In the UK and North America, personal space is highly valued and fiercely guarded. Broadly speaking, there are four personal space zones. The first is the "intimate" zone, where we only allow access to family, partners and very close friends. It's not quite a free for all, but our personal space boundaries are generally more relaxed, less rigid and more open to touch. This zone is reserved for those who share our genes, our familial scent and when crossed by others who do not fall into this category or are uninvited, we normally become alarmed and feel a bit creeped-out. Our natural response is to move further away, or exit the space completely.

The second zone is probably the one that most of us mean when we use the term "personal space". In this arena, we normally expect people to stand about three or four feet away from us. If we are talking to people we don’t know well or dealing with people at work, we need enough space to feel safe and comfortable. This is also the zone where micro-transgressions are more frequent and more irritating (where folk stand too close or look at you too intensely for too long, or touch you in a way that feels unwarranted and unwelcome).

Beyond this zone, is social space. In a group meeting or in the seating areas in a restaurant or library, for example, we generally feel comfortable when others are about six to 10 feet away from us. The final frontier is the world at large, the public zone where we have a peripheral awareness of other bodies moving around the park or along the other side of the street but they remain distant, impersonal blots on the landscape.

Our awareness and sensitivity to the personal space of others is closely related to our emotional intelligence and capacity for empathy. Those who lack this kind of awareness tend to create discomfort or alarm in others, who experience their over-proximity as threatening. This is a primitive reaction similar to the fight or flight response when we perceive danger. Situational factors such as overcrowding on the bus or underground necessitate us being closer to others and so we recalibrate our expectations and tolerate the proximity.

But even in this context, there are still unspoken rules about how we manage the adjustment to our personal space. There is a good way and a bad way of standing too close to someone. The primitive part in us senses who is safe and who is dangerous. It's all in the body language and the smell of those who stand or sit close to us. We can mock the anti-manspread campaigns and say they are gender-biased, but in fact, taking up two seats instead of one while others have to fit in around you and travel in less comfort, is essentially anti-social.

Women, of course, have their own kind of space-imperialism. We’ve all seen the "bag on seat" trick, which sends out its passive-aggressive warning to stay away. My own way of dealing with this scenario is simply to ask the female passenger if she thinks her bag would mind if I sat there for a bit. Usually the bag does mind, but moves anyway.