One of my boys has his birthday this weekend. Even if he hadn't been reminding me on a daily basis, I wouldn't have been able to ignore it: when I come home and try to push the door open, it resists. There is a heap of handwritten envelopes – birthday cards – on the floor. It's funny how we still receive them. I remember a boss of mine sending me an e-card many years ago and telling me that "E-cards are the future! We won't send paper cards any more." I suppose we keep with the paper cards since it makes us feel old-fashioned; birthdays are as much about continuity as they are change. I got cards from my mum and dad. I like to give them to my children too.

But other ways of communicating have changed. And even if we don't use paper as much, it is not always clear that the changes are for the better. At work I seem inundated by email. When I come home, I find my daughter lounging on the couch, "doing Facebook" as she puts it. I wonder whether she will have time to do her homework with all the postings she seems to do. She growls at me when I ask.

And things could be about to change again. Last week, Mark Zuckerberg, the Facebook founder and CEO, announced that his company was to launch a new email messaging system. He wasn't seeking to elbow in on free email services. This service would be "something different". Traditional email is made for intermittent exchanges of content, he explained, whereas this new messaging medium will support "ongoing conversations".

If, in the past, Facebook allowed people to come together in a broken-up sort of way, with a person creating a message, "posting" it and waiting for their friends to reply, with this new system people will be constantly aware of one another's communications. They will be instantaneously and continuously connected. But many commentators have remarked that this new communications channel might be a step too far. It won't just make communications easier. In a world where we already have emails, texts, instant messaging, video conferencing and mobile phone calls, it could lead to communications overload.

I already feel under pressure. More phone calls are made, more texts sent and more emails received than ever before. This comes at the cost of not doing other things, whatever those might be. It's not just me who complains of being overloaded by the constant barrage of messages. We all do.

It's not how efficient our communications channels are that is beginning to worry us, but why we use them and how we might become further obsessed by them. It's what communication is for that is turning out to be the issue.

Being able to experience instantly the views and expressions of friends and loved ones is appealing. Our lives are constrained by geography. We have to take the kids to school and then go to work; we cannot always be at home with our partners. With changing technology, we might overcome the limitations placed upon us by geography.

But it's not the increased volume of messaging that changing technologies offer – it's the different forms of communication they allow that is critical – and we must learn to appreciate the different needs they can meet, and train ourselves to use each one properly.

In the 19th century, when the written letter first became widely used, the delight it afforded came in overcoming physical separation. But people discovered that letters offered something else too: the written word could allow a person to express themselves candidly in ways that were not possible face to face. People discovered that they could articulate themselves with more finesse with the written word. In short, distance became a pretext to communicate in a special kind of way.

To be instantly in touch is something that I want to achieve only with some people some of the time. I certainly don't want this level of constant communication with colleagues. Sometimes it's fine – when I have a question or a doubt about something. But on other occasions I simply want them to send stuff that I can deal with in my own time. And it is not just information about work – it might be advice, even a bit a gossip or a joke. I may indeed want instant communication with my partner. But if I choose to be this close all the time, won't she get irritated with me for demanding too much attention? Won't her colleagues complain she is giving them too little?

The issue here is how different communications technologies afford different sorts of ways of being in touch. Take another example: when I post on my Facebook account, I mostly do not want an instant response. All I am doing is raising a flag to describe what I am thinking or doing, hoping that at some later time friends might come back to make conversation – on the phone, or at the pub, or even on Facebook itself the next day, where they might post some remarks next to my own: "You were having a bad day yesterday, well, I am having an even worse one today!"

Technology companies have made a fortune out of inventing new ways of being in touch. But they seem to forget the rich variety of ways in which people already choose to do this, and instead of offering more ways, seem to think that people only want one medium. They should recognise that people have different needs at different times.

Sometimes they choose one means of communication over another because the expression that it enables is taut and quick. SMS can have this capacity, for example. At other times, people choose a different method because it is loose and slow, or gentle – and so treats those being addressed gently in turn. A voice message can have this quality. A third method might be selected because it is permanent and inviolate: however much those being addressed try to avoid one's missive, they will find it cannot be undone. This is why people still write letters. A fourth is chosen because it is ephemeral, although it is offered as a token of regard. The Facebook postings I mentioned above are of this order.

If this is the case, then the concern that we might have reached an overload might be missing the point. The issue is not that we will spend too much time communicating. It is that we might not be communicating in the right way – spending too much time on one mode, not enough on another.

Just as there were numerous books and courses developed in the 19th century to teach people the art of letter writing, so we now ought to be thinking of teaching ourselves how to make the best of the increasingly rich communications landscape. At school, kids are taught to use PowerPoint, but they are not taught to think about how Facebook is a different form of communication than, say, email or a video call.

Often they are told to worry about what they post on Facebook, with concerns about privacy and stalkers being uppermost, but they are not encouraged to think that part of the skills of adulthood are deeply bound up with how adroitly one uses communications technologies.

So Zuckerberg's announcement has hit a nerve – but not because of the number of messages we now receive. It's because his announcement is asking us to think about who we want to be and how we convey that through our communications. These are human questions, not technical ones, and all the more important because of it.

Richard Harper is principal researcher at Microsoft Research, Cambridge. His book 'Texture: Human expression in the age of communication overload' (MIT Press) is out next month