For twenty years David Rokeby has been at the vanguard of new media arts, matching tech­no­lo­gic­al know-how with con­cep­tu­al rigour, and, as the title of this ret­ro­spect­ive suggests, a firm focus on the re­la­tion­ship between humans and their computers.

When you enter the gallery that houses the first piece on show, Taken, the rear wall is a grid of blurred faces rendered in grainy black and white. Then, as you study the wall of un­re­co­g­n­is­able people, the in­stal­l­a­tion springs into action, switching to a dual screen format. On the right you see yourself, sur­roun­ded by the ghost images of previous visitors, and, as time passes, by ghost images of yourself, seconds before. This is an uncanny ex­per­i­ence, observing oneself being observed, and it gets worse. A white box appears on the orange screen, homes in on your head, and, at the same moment, the screen to the left displays one of those grainy mono­chrome faces, blown up to wall-size, this time your own. There are captions, too, reading ‘under ob­ser­va­tion’, ‘nervous’, or, a little less threat­en­ingly, ‘dis­in­ter­es­ted’. The piece can be turned into a game - moving into the spaces once occupied by previous visitors is good fun - but that feeling of dis­com­fort never quite dis­sip­ates. It can be seen as a work about memory, too, with Rokeby’s system granting the room an awareness of its in­h­ab­it­ants, past and present. But, ul­ti­m­ately, Taken is a political piece, with par­t­ic­u­lar resonance in the UK, where there is one sur­veil­lance camera for every fourteen people, and trials of Talking CCTV have brought Orwellian control to our city centres with nary a word of protest. In other words, Taken is like a walk down the average British high street, the only di­f­fer­ence being a visceral awareness of being watched, an awareness that takes time to fade after leaving the gallery.

Thank­fully, Taken is followed by a much more pleasing ex­am­in­a­tion of our re­la­tion­ship with tech­no­lo­gy. The Giver Of Names em­phas­ises the logic-bound un­soph­ist­ic­a­tion of computers. Gallery-goers are asked to choose an object from a selection of objects, mostly toys, and place it on a plinth. The system then analyses the object’s char­ac­ter­ist­ics and matches them to a database of words and phrases, out­put­t­ing poetic phrases on a screen. I chose a pink child-size Wel­ling­ton boot, and the computer, after a brief pause, said, ‘A boot withdraws from the brownish boot.’ A plastic bowling pin provoked a rather more peculiar response: ‘The next con­ser­vat­ive on the left is ten­der­ised by a bowling pin’. Rokeby’s aim here is, in exposing the faulty thinking of a machine, to force us to think again about our own thought processes, the lightning-quick flow of as­so­ci­a­tions provoked each time we register the presence of an object or, for that matter, a work of art.

Machine For Taking Time is poetic too, even elegiac. Images of a garden, hundreds of them taken over a three year period, hove into view, the camera re­peatedly panning from left to right. And, while space remains constant, Rokeby breaks time, his software morphing a bright summer’s day into a snowbound scene, un­n­at­ur­ally mingling the seasons, turning the regular irregular, bending linear time to the artist’s will. Like The Giver Of Names, this is a piece of tech­no­lo­gy intended to make us question our re­la­tion­ship with the world, upending the cer­tain­ties of per­cep­tion.

The last work in the CCA’s main gallery is Seen, a four screen work that draws together the main threads that run through Rokeby’s work. Four screens show four processed views of the Piazza San Marco, Venice. In one, all movement has been removed, leaving only the square itself, and a few sta­tion­ary tourists. In another, the reverse is true, with nothing but movement visible. The twin central screens, meanwhile, offer almost painterly views, one tracking movement through space, the other showing slow-moving waves of motion in a constant state of ebb and flow. Once again, the computer’s mono­ma­n­i­ac­al vision is clashed with the human, and, once again, Rokeby has us question the validity of our per­cep­tion, showing it to be a mental construct rather than a true re­p­res­ent­a­tion. The passage of time, and its in­ter­pret­a­tion through memory is contained in Seen, too, making for a work that is complex, but one that, thanks to the digital brushtrokes of the central screens, is also simply beautiful.

Last of all, housed in the CCA’s resource room, is Very Nervous System, a work that Rokeby has been revising since 1986. This system of sensors, syn­thes­isers and speakers turns human presence and movement into sound. Wiggle a finger, and the walls emit digital squeaks, jig about a bit, and they bellow out a cacophony of metallic clangs and robotic whirrs. It’s a good piece to end the show with: after the paranoia-inducing Taken, and the often rather dry, clinical ex­per­i­ment­a­tion of other works, the Very Nervous System shows Rokeby’s playful side, with the invisible interface proving that man and machine can play together.