mongit: Visual illusions that change how you think

Cormac Sheridan, contributor

(Image: Cleary & Connolly)

Halfway through a visit to Hall of Mirrors, Anne Cleary's and Denis Connolly's newly opened show at the Farmleigh Gallery in Dublin, I'm suddenly reminded of comedian Harry Worth's signature optical prank that opened every episode of his legendary sitcom series. On one level it seems like a pretty feeble and inadequate response to what is a sophisticated, scientific exploration of visual perception. Yet Hall of Mirrors shares some of Worth's playful humour. It also serves as a reminder of the simple brain-tickling pleasures of experiencing visual distortion.

The Paris-based Irish couple has, with the help of researchers at the Clarity Centre for Web Sensor Technologies at Dublin City University and at the Laboratoire Psychologie de la Perception at Universit? Paris Descartes, created a series of live and recorded 2D and 3D video installations that illustrate the complex interplay between vision perception, movement and time. Sally Duensing at King's College London and Patrick Cavanagh of Harvard University also contributed to the development of the project.

The duo has explicitly avoided creating a series of optical tricks that can be triggered simply by viewers waving their hands in front of a camera. While a certain amount of handwaving can be (and, in my case, was) indulged in, their intention was to probe more deeply than that into how we see the world.

In Dutch Wax, a large projected black and white image of a human face appears to be in colour when viewed immediately after seeing a colour-saturated image first. But it only works if you stare at the same spot - as soon as you move your eyes the effect disappears. This, Connolly tells me, is a demonstration of microsaccades, which are tiny involuntary movements of the eyes that play a role in colour perception. Without them, our colour-sensing photoreceptors become fatigued and our perception of colour fades out.

Playing around with binocular vision,?Lough in a Box?is a version of an installation at Lough Lannagh, near Castlebar, in County Mayo, called On Sight. It divides eight different films shot at the lake into pairs that are viewed through a binocular viewer, so your left and right eyes are seeing a different film shot at precisely the same location - in precisely the same frame. The trick creates disconcerting transitions. First the left eye dominates and one film is perceived. Then the right eye takes over and you're looking at the other film, before you achieve a binocular combination of the two. In one instance, this conjured up the surreal spectacle of a teddybears' picnic happening in parallel with a group of men who appear to be about to load a large ornamental swan onto a truck.

(Image: Cleary & Connolly)

Dot Universe, on the other hand, plays on Swedish psychologist Gunnar Johansson's seminal research on the perception of biological motion in the 1970s. Johansson demonstrated that an array of just thirteen dots, positioned at the body's cardinal points, is sufficient to create the illusion of a moving human figure. Cleary and Connolly re-created that effect but then jumbled up the results to create what resembles a dynamic, shape-changing constellation that moves with a pleasing, loose-limbed elasticity. A version of this work, Joining the Dots,
has already been installed in Tralee, County Kerry. As Connolly notes, it demonstrates "the refusal of the mind to accept abstraction". Even when an image appears to be formless or random, we're constantly looking for patterns or shapes that we can interpret and render into meaning.

Sometimes it is harder to understand what you?re looking at though. Look Both Ways is a 'timeslice' video inspired by an early photograph by?French photographer Jacques Henri Lartigue, in which the rear wheel of a racing car appears to tilt forward, while, in the background, the watching spectators and static telegraph poles appear to tilt in the opposite direction. The photographer was also moving in an adjacent car, albeit at a slower speed. That, combined with a slow shutter speed, the large format of the camera and the photographer's panning movement created the distortion. "For us, that expresses movement in a certain way," says Cleary. "We'd like to do that with video."

The result, which is part of a public art project for the Railway Procurement Agency to mark an extension to Dublin's Luas lightrail system, is strange. The split-screen video of a train journey seen from two perspectives, in which one frame seems to unspool from or merge into another, was difficult to decipher. The confusion is all part of the fun - seeing, in this instance, does not necessarily mean believing.

Hall of Mirrors runs?at the Farmleigh Gallery in Dublin, Ireland,?until 22 July and will then tour nationwide.