Jacob Dahlgren has worn a striped t-shirt every day for the last eight years. Yes, every day. And most likely he never has to wash a single one, as he has around 900 in his wardrobe. That must be one for every instance of stripes in the world at large: the Venetian gondolier, the seaside deckchair, the ice-cream parlour awning, the lighthouse, the humbug, the mild eccentric's socks, the barber's pole, the candy cane, the skunk, the tiger, the medal ribbon, the old school tie …

I too have been wearing stripes for 20 years, albeit more sporadically, ever since I saw Alain Delon clambering over a yacht in a Breton t-shirt in Le Plein Soleil - the paragon of cool I understood to be at once feared and followed. I had no knowledge of the cultural ambivalence of the striped garment at the time, but nonetheless sensed its ancient severity and wayward modernity. In medieval Europe stripes were worn by outcasts, transgressives and underlings, with prostitutes, servants and convicts bearing the mark with fortitude. In more liberal times it has been appropriated as a motif of modernity and co-opted by the happily flamboyant or the super-smart set. Go-faster stripes, elegant pin stripes and chic, wipe-clean banded accessories have come to signal the efficiency and cleanliness of an illuminated era, elevated from the grime. The bold, the unbending, the bright and uninflected stripe marks the irrefutable passage of a huge ship, the zippiness of a sportsperson or the power of an army officer passing up through the ranks; while the livery of the stinging wasp, exclamatory bollard and prohibitive hazard tape remind us of fundamental associations with danger and authority.

The stripe, then, is a conflicted emblem. Its reading depends more on the context of its display than any constancy of meaning. It is a malleable signifier, and yet there is one immutable quality of the stripe: its absolute reference to surface rather than three-dimensional form. The stripe, once it passes through the mass of a substance, becomes a stratum, a volume, another matter altogether. The stripe is a surface dweller, and this is where its ontology intersects with art history. Its adherence to a façade makes it indispensable to the abstract painter of the 20th century, as it compels the eye to rest on the plane of the canvas, negating any window-like view through to other spaces elsewhere. The stripe is firmly in the here and now.

In the history of 20th century painting straight-edged delineations of bold colour have generated many effects, from the irreverence of Pablo Picasso's harlequins and whores to Barnett Newman's hallowed zips and Bridget Riley's composite dazzles. And yet all of these examples flag the artists' preoccupations with the mechanics of looking rather than the theatrics of representation. These particular stripes have been put to work to communicate cubistic multiplicity, existential self-encounter and optical effervescence - effects that have also been conjured in the 'real' world, in dazzle camouflage on war ships, for instance, or the placating colour schemes of hospital wards.

Dahlgren's performance, Signes D'Abstraction, brings together such modes of optical and physical experience with another, socialising aspect. Upwards of 350 people, aged between two and 97 and wearing their own striped clothing, converged on a shopping mall in Stockholm with instructions to congregate in the cafés and only give their seat up to someone else wearing stripes. Before long the eateries and watering holes at the centre of the mall were vibrant with stripes - there was not a plain-clothed person in the place. Other groups were directed to flock to an escalator or a particular shop, creating temporary effervescing hotspots before melting back into the general flux of shoppers. People broke out of their usual groupings and struck up conversations with strangers who also bore the stripe, a distinct camaraderie forming between fellow participants, despite the somewhat arbitrary law of fellowship. How mischievous of Dahlgren to turn the badge of otherness into the uniform of a gang, a stigma into a marker of acceptability.

Like a painter's palette, the dark and light, broad and narrow, primary and secondary schemes of coloured stripes were reconfigured throughout the day in endless permutation. The participants started to play out the role of paintings in a constantly reconfiguring exhibition, so that the mall - usually a space for conspicuous consumption of mainstream culture - became, through the simple flick of an artist's wrist, a singular point of production. Although a profound intellectual epiphany is rarely, if ever, experienced during the execution of socially engaged artwork, unexpected social interactions do have a distinct effect. The realisation that anyone can be part of an artwork simply by hanging out in an old t-shirt is a breakthrough for many, as the misconception persists that art is about the uniquely crafted object, singular authorship and fixed meaning. The social and ultimately undirected nature of Signes D'Abstraction reminds us that to represent humanity artists might consider it as a living, near-autonomous medium in and of itself.

Literary theorist Steven Connor points out in an essay on the significance of spots, dots, blotches and patches: 'Much of the symbolism of stripes may rest on the fact that they are relatively rare in nature. For this reason, stripes will usually suggest some purposeful marking out or setting apart. Through signifying some design, stripes suggest the hand of some artificer, or even an act of self-designation.' And if you study the wearing of stripes you can indeed perceive how taste, fashion, social conditioning, media manipulation and all sorts of other factors inform each person's choice. So in Signes D'Abstraction the visual effect of becomes one based on difference rather than similarity: the broad or narrow, vertical or horizontal, the binary or multivalent, subtle or garish, the upper or lower parts of the body, the harmonious or discordant combinations - these axes of differentiation are vital. Perhaps what Dahlgren wishes us to acknowledge is that there can be no standard, that all stripes are a variation on a theme and all themes are valid; and yet all themes are equally vulnerable to clashes with the themes of others. Indeed, we will do well to remember that solidarity can be established through mutual vulnerability, as well as power.

Sally O'Reilly