Les Binet and Sarah Carter get a little bit angry about some of the nonsense they hear around them… like the idea that we are 'typical'.

Two seemingly unrelated things happened recently that made us a feel a bit worried. Firstly, a young planner was telling us why she enjoys working on digital stuff more than TV. "Of course, people spend lots more time online these days than watching TV," she said. We pointed out that the data shows that people spend a lot more time watching TV. "Oh, I don't believe that" she said, "I mean I don't…"

Next day we were somewhere very different. The venue was a bungalow on a small housing estate just outside Manchester – we were talking to a room of women in their 60s. We hadn't met them before and we wouldn't meet them again. But they shared their concerns and hopes for their lives in a way that was fascinating, funny and thought-provoking. Perched on stools in that sitting room, we were ashamed to realise we couldn't remember the last time we had spoken to people face to face in someone's house outside London.

Is there a link between these two observations? At a time when the world is supposedly more open and connected than ever before, are planners ironically becoming more insulated and isolated from the 'real world'?

All of us have a tendency to assume we are typical. Psychologists talk about The Typical Mind Fallacy (other people are just like me), False Consensus Bias (everyone else thinks like me) and Confirmation Bias (yes, I am right). Our new digital, multi-channel world can easily exaggerate these effects. The internet makes it easier than ever to meet like-minded souls, to find sources of information that match our interests and views. It's all too easy to construct a media bubble, where everything we see or read confirms our preconceptions – where, un-tempered by contrasting points of view, our thinking becomes more and more detached from reality. Some think this effect contributed to Romney's defeat in the US election. Republicans living on a diet of Fox News and Tea Party blogs just didn't understand how ordinary voters failed to share their views.

In our opinion, advertising people can make similar mistakes. Pushed for time and money, planners are finding it ever harder to get out of the agency, let alone trek up the motorway to do groups in some suburb. Far cheaper and quicker to use the internet, do a quick survey of agency staff, or read another planner's blog.

Trapped in our advertising bubble, it's easy to lapse into making stuff for people like ourselves. But our audiences are usually very different – older, poorer, more female, less London-centric, less educated, more likely to have kids or grandchildren, and with very different media habits. One of our great young planners tried to remind himself of this with a Post-It note above his desk, saying "Remember: people who buy new cars are OLD!"

If we're to avoid losing touch with our audiences, we have to really connect and talk to them. We were appalled when a planner recently confessed that he had never talked face to face with any of his target audiences during his career. New digital techniques ('mobile ethnography', etc.) can certainly help. But we've always felt that much of the value of focus groups lay in simply getting out of the agency and into people's houses.

Of course, you don't even have to 'do research' to do that. The late great BMP creative John Webster attributed his amazing popular appeal to his deliberate shunning of 'the ad world', and his preference for discussing his ideas with Pat the office tea lady or Ray the building manager, rather than fellow creatives.

So don't hang around too much in the office. Look out of the window, not in the mirror. Get out there. Get a life. And don't read planning blogs like ours!