From posters … to posters.

The movement of text from a series of 140 character Tweets found on the fecund social network system Twitter, to an old-school, full scale poster pasted on a wall, is at the heart of the Dundee Wall, the major artwork in a new exhibition opening at Dundee Contemporary Arts tomorrow.

The artists behind this transfer of writing on the internet to poster-paint are former students and residents of the city, returning with a major show after a 20-year absence. Jon Thomson & Alison Craighead are an artistic, and real life, partnership who are fixated with the internet and the web,its flows and conversations, its arguments and nodes of information, its misinformation, its images, maps, and uncertain, marginal areas. The show, Maps DNA And Spam (a title, which you might notice, is a palindrome) is the largest Scottish solo show for the artists, who both studied in the early 1990s at Duncan Of Jordanstone Art College.

Now based in London and Speyside, their work was recently lauded by Grayson Perry in his BBC Reith Lecture. He said of their "very interesting" work: "They do thought-provoking, lyrical, often hilarious interventions with the kind of flow of information that is pouring around the web."

Their works, such as A Short Film About War, which is in the Dundee show, can be lengthy, documentaries drawn from the white-noise buzz of information on the web. Others, like their permanent web pieces, or Corruption, also in the show, take the glitches, corruptions and maths of the 'net and turns them into blinking, fuzzy online art works.

Over a cup of tea in the DCA cafe, as their exhibition was being installed, the couple explain how they have harvested Tweets for Dundee Wall, the centre of the show. Tweets from the area have been taken by the duo and turned, by hand, into posters: typeset, printed and posted across a gallery wall in chronological order. The messages are mundane but sometimes telling: people struggling to get out of bed, moaning about the costs of car parks, tips for exercise classes, ordering pizza, complimenting Dundonian taxis (excellent, apparently), the extensive demolitions on the city's waterfront, and the civil war in Syria.

The artists have performed similar exercises in Tallin and London. The quietly spoken Craighead (originally from Aberdeen, born in 1971) says: "It's a performance, that is how we see it: it is like a collaborative performance with the people of Dundee. We watch what people are saying within 20 miles of the GPS location of the gallery. We have been looking at what people are saying, taking those interesting Tweets and making them into posters. We notice in Dundee it is a younger demographic Tweeting - school age, at college, football fans - and a lot of people running for pizza."

Thomson, born in 1969, adds: "It is taking micro-blogging and turning into an older technology. It is like slowing Twitter down a bit, turning it into a cloud of information. We are fascinated about how seamless experiences can be constructed, but also the cracks between them. We all participate in this world now, which is part web, part real world, but we are not particularly interesting in critique, we are more holding a mirror up to our world."

The internet, as we all know, has transformed our lives, but it did not exist for most people when the duo were studying in Dundee. Like many students, they were given their first email addresses around 1993/4. Craighead studied in Dundee as an undergraduate, with Thomson studying Electronic Imaging on a post-graduate course. Thomson now teaches at Slade School Of Fine Art in London, with Craighead lecturing at Goldsmiths.

Thomson says: "We both studied drawing and painting, and then we moved into video, and photography. And the editing systems for those started to migrate on to computers. We began using these computers, and they began to be online, which was not always a given, but we began to be more aware of this space, the web. In a way we were one of the very last generations to grow up with the internet, and so spaces like the web, that space where you connect anything to anything else, became fascinating to us as artists. Then we started working with it and experimenting.

"Also, we just could not afford a studio. But we could afford a computer and so we began using them as these experimental spaces, to connect images together. It had a profound effect on us."

Other works in the show include The Time Machine In Alphabetical Order, a film of the 1960 movie, but re-edited to play in alphabetical order according to every word spoken. Like much of their work, it is painstaking and took a long time - years - to create. Two more works, First Person and Belief, take imagery from the internet for pieces that ruminate on hard-held convictions and the language of the self-help industry.

Thomson adds: "We are really, I think, at a midway point where the internet is ever more becoming attached to the reality around us. It is properly a layer of augmentation on top of reality. That is what the works in our exhibition look at. We have been making these, what we call, 'desktop documentary' artworks that are exclusively made out of things we have found online."

Key among these works is A Short Film About War, which takes the viewer through a series of war zones, using GoogleMaps as an apparent guide, as well as Flickr, bloggers, and other first-hand accounts.

Thomson says: "We use Google Earth as a visual metaphor, and it is a treacherous one. It leads you to believe - the interface convinces you - that you can bounce around the world with this panoptic gaze, but in reality you can experience more of life just by going to the supermarket."

Craighead adds: "It is complex and treacherous: you think you can see everything, and sometimes in your mind, you think you are seeing it in real time, too. Of course you are not, and you have very little control of what you can see: try and look at China on it, it is almost all blurred."

Thomson: "You cannot see child soldiers. You see a partial view of the world. The miracle of the internet is that you can read a blogger in Gaza and see his images on Flickr and see his video on YouTube, but how much are you really interacting?"

"It is a call for you to just sit in your seat, and let all this information come to you. You are far more passive than you think in all of this."

Thomson & Craighead, Maps DNA And Spam, DCA, Dundee, tomorrow to March 16

l www.thomson-craighead.net

l www.dca.org.uk